kc3-lang/angle/src/tests/gl_tests/WebGLCompatibilityTest.cpp

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• Author : Geoff Lang
  Date : 2017-02-21 16:48:43
  Hash : d7d526ad
  Message : Allow enabling GL_EXT_texture_filter_anisotropic. BUG=angleproject:1721 Change-Id: I7cbc734915cde7d09165a3fcfe9a6bc0d7149aff Reviewed-on: https://chromium-review.googlesource.com/445959 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>

• src/tests/gl_tests/WebGLCompatibilityTest.cpp

• //
  // Copyright 2015 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  // WebGLCompatibilityTest.cpp : Tests of the GL_ANGLE_webgl_compatibility extension.
  
  #include "test_utils/ANGLETest.h"
  
  #include "test_utils/gl_raii.h"
  
  namespace
  {
  
  bool ConstantColorAndAlphaBlendFunctions(GLenum first, GLenum second)
  {
      return (first == GL_CONSTANT_COLOR || first == GL_ONE_MINUS_CONSTANT_COLOR) &&
             (second == GL_CONSTANT_ALPHA || second == GL_ONE_MINUS_CONSTANT_ALPHA);
  }
  
  void CheckBlendFunctions(GLenum src, GLenum dst)
  {
      if (ConstantColorAndAlphaBlendFunctions(src, dst) ||
          ConstantColorAndAlphaBlendFunctions(dst, src))
      {
          EXPECT_GL_ERROR(GL_INVALID_OPERATION);
      }
      else
      {
          ASSERT_GL_NO_ERROR();
      }
  }
  
  }  // namespace
  
  namespace angle
  {
  
  class WebGLCompatibilityTest : public ANGLETest
  {
    protected:
      WebGLCompatibilityTest()
      {
          setWindowWidth(128);
          setWindowHeight(128);
          setConfigRedBits(8);
          setConfigGreenBits(8);
          setConfigBlueBits(8);
          setConfigAlphaBits(8);
          setWebGLCompatibilityEnabled(true);
      }
  
      void SetUp() override
      {
          ANGLETest::SetUp();
          glRequestExtensionANGLE = reinterpret_cast<PFNGLREQUESTEXTENSIONANGLEPROC>(
              eglGetProcAddress("glRequestExtensionANGLE"));
      }
  
      // Called from RenderingFeedbackLoopWithDrawBuffersEXT.
      void drawBuffersEXTFeedbackLoop(GLuint program,
                                      const std::array<GLenum, 2> &drawBuffers,
                                      GLenum expectedError);
  
      // Called from RenderingFeedbackLoopWithDrawBuffers.
      void drawBuffersFeedbackLoop(GLuint program,
                                   const std::array<GLenum, 2> &drawBuffers,
                                   GLenum expectedError);
  
      PFNGLREQUESTEXTENSIONANGLEPROC glRequestExtensionANGLE = nullptr;
  };
  
  class WebGL2CompatibilityTest : public WebGLCompatibilityTest
  {
  };
  
  // Context creation would fail if EGL_ANGLE_create_context_webgl_compatibility was not available so
  // the GL extension should always be present
  TEST_P(WebGLCompatibilityTest, ExtensionStringExposed)
  {
      EXPECT_TRUE(extensionEnabled("GL_ANGLE_webgl_compatibility"));
  }
  
  // Verify that all extension entry points are available
  TEST_P(WebGLCompatibilityTest, EntryPoints)
  {
      if (extensionEnabled("GL_ANGLE_request_extension"))
      {
          EXPECT_NE(nullptr, eglGetProcAddress("glRequestExtensionANGLE"));
      }
  }
  
  // WebGL 1 allows GL_DEPTH_STENCIL_ATTACHMENT as a valid binding point.  Make sure it is usable,
  // even in ES2 contexts.
  TEST_P(WebGLCompatibilityTest, DepthStencilBindingPoint)
  {
      GLRenderbuffer renderbuffer;
      glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer.get());
      glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 32, 32);
  
      GLFramebuffer framebuffer;
      glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get());
      glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
                                renderbuffer.get());
  
      EXPECT_GL_NO_ERROR();
  }
  
  // Test that attempting to enable an extension that doesn't exist generates GL_INVALID_OPERATION
  TEST_P(WebGLCompatibilityTest, EnableExtensionValidation)
  {
      glRequestExtensionANGLE("invalid_extension_string");
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  }
  
  // Test enabling the GL_OES_element_index_uint extension
  TEST_P(WebGLCompatibilityTest, EnableExtensionUintIndices)
  {
      if (getClientMajorVersion() != 2)
      {
          // This test only works on ES2 where uint indices are not available by default
          return;
      }
  
      EXPECT_FALSE(extensionEnabled("GL_OES_element_index_uint"));
  
      GLBuffer indexBuffer;
      glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer.get());
  
      GLuint data[] = {0, 1, 2, 1, 3, 2};
      glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW);
  
      ANGLE_GL_PROGRAM(program, "void main() { gl_Position = vec4(0, 0, 0, 1); }",
                       "void main() { gl_FragColor = vec4(0, 1, 0, 1); }")
      glUseProgram(program.get());
  
      glDrawElements(GL_TRIANGLES, 2, GL_UNSIGNED_INT, nullptr);
      EXPECT_GL_ERROR(GL_INVALID_ENUM);
  
      if (extensionRequestable("GL_OES_element_index_uint"))
      {
          glRequestExtensionANGLE("GL_OES_element_index_uint");
          EXPECT_GL_NO_ERROR();
          EXPECT_TRUE(extensionEnabled("GL_OES_element_index_uint"));
  
          glDrawElements(GL_TRIANGLES, 2, GL_UNSIGNED_INT, nullptr);
          EXPECT_GL_NO_ERROR();
      }
  }
  
  // Test enabling the GL_EXT_texture_filter_anisotropic extension
  TEST_P(WebGLCompatibilityTest, EnableExtensionTextureFilterAnisotropic)
  {
      EXPECT_FALSE(extensionEnabled("GL_EXT_texture_filter_anisotropic"));
  
      GLfloat maxAnisotropy = 0.0f;
      glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &maxAnisotropy);
      EXPECT_GL_ERROR(GL_INVALID_ENUM);
  
      GLTexture texture;
      glBindTexture(GL_TEXTURE_2D, texture.get());
      ASSERT_GL_NO_ERROR();
  
      glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, 1.0f);
      EXPECT_GL_ERROR(GL_INVALID_ENUM);
  
      GLfloat currentAnisotropy = 0.0f;
      glGetTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, &currentAnisotropy);
      EXPECT_GL_ERROR(GL_INVALID_ENUM);
  
      if (extensionRequestable("GL_EXT_texture_filter_anisotropic"))
      {
          glRequestExtensionANGLE("GL_EXT_texture_filter_anisotropic");
          EXPECT_GL_NO_ERROR();
          EXPECT_TRUE(extensionEnabled("GL_EXT_texture_filter_anisotropic"));
  
          glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &maxAnisotropy);
          ASSERT_GL_NO_ERROR();
          EXPECT_GE(maxAnisotropy, 2.0f);
  
          glGetTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, &currentAnisotropy);
          ASSERT_GL_NO_ERROR();
          EXPECT_EQ(1.0f, currentAnisotropy);
  
          glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, 2.0f);
          ASSERT_GL_NO_ERROR();
      }
  }
  
  // Verify that shaders are of a compatible spec when the extension is enabled.
  TEST_P(WebGLCompatibilityTest, ExtensionCompilerSpec)
  {
      EXPECT_TRUE(extensionEnabled("GL_ANGLE_webgl_compatibility"));
  
      // Use of reserved _webgl prefix should fail when the shader specification is for WebGL.
      const std::string &vert =
          "struct Foo {\n"
          "    int _webgl_bar;\n"
          "};\n"
          "void main()\n"
          "{\n"
          "    Foo foo = Foo(1);\n"
          "}";
  
      // Default fragement shader.
      const std::string &frag =
          "void main()\n"
          "{\n"
          "    gl_FragColor = vec4(1.0,0.0,0.0,1.0);\n"
          "}";
  
      GLuint program = CompileProgram(vert, frag);
      EXPECT_EQ(0u, program);
      glDeleteProgram(program);
  }
  
  // Test that client-side array buffers are forbidden in WebGL mode
  TEST_P(WebGLCompatibilityTest, ForbidsClientSideArrayBuffer)
  {
      const std::string &vert =
          "attribute vec3 a_pos;\n"
          "void main()\n"
          "{\n"
          "    gl_Position = vec4(a_pos, 1.0);\n"
          "}\n";
  
      const std::string &frag =
          "precision highp float;\n"
          "void main()\n"
          "{\n"
          "    gl_FragColor = vec4(1.0);\n"
          "}\n";
  
      ANGLE_GL_PROGRAM(program, vert, frag);
  
      GLint posLocation = glGetAttribLocation(program.get(), "a_pos");
      ASSERT_NE(-1, posLocation);
      glUseProgram(program.get());
  
      const auto &vertices = GetQuadVertices();
      glVertexAttribPointer(posLocation, 3, GL_FLOAT, GL_FALSE, 4, vertices.data());
      glEnableVertexAttribArray(posLocation);
  
      ASSERT_GL_NO_ERROR();
      glDrawArrays(GL_TRIANGLES, 0, 6);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  }
  
  // Test that client-side element array buffers are forbidden in WebGL mode
  TEST_P(WebGLCompatibilityTest, ForbidsClientSideElementBuffer)
  {
      const std::string &vert =
          "attribute vec3 a_pos;\n"
          "void main()\n"
          "{\n"
          "    gl_Position = vec4(a_pos, 1.0);\n"
          "}\n";
  
      const std::string &frag =
          "precision highp float;\n"
          "void main()\n"
          "{\n"
          "    gl_FragColor = vec4(1.0);\n"
          "}\n";
  
      ANGLE_GL_PROGRAM(program, vert, frag);
  
      GLint posLocation = glGetAttribLocation(program.get(), "a_pos");
      ASSERT_NE(-1, posLocation);
      glUseProgram(program.get());
  
      const auto &vertices = GetQuadVertices();
  
      GLBuffer vertexBuffer;
      glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer.get());
      glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                   GL_STATIC_DRAW);
  
      glVertexAttribPointer(posLocation, 3, GL_FLOAT, GL_FALSE, 0, 0);
      glEnableVertexAttribArray(posLocation);
  
      ASSERT_GL_NO_ERROR();
  
      // Use the pointer with value of 1 for indices instead of an actual pointer because WebGL also
      // enforces that the top bit of indices must be 0 (i.e. offset >= 0) and would generate
      // GL_INVALID_VALUE in that case. Using a null pointer gets caught by another check.
      glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, reinterpret_cast<const void*>(intptr_t(1)));
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  }
  
  // Tests the WebGL requirement of having the same stencil mask, writemask and ref for fron and back
  TEST_P(WebGLCompatibilityTest, RequiresSameStencilMaskAndRef)
  {
      // Run the test in an FBO to make sure we have some stencil bits.
      GLRenderbuffer renderbuffer;
      glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer.get());
      glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 32, 32);
  
      GLFramebuffer framebuffer;
      glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get());
      glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
                                renderbuffer.get());
  
      ANGLE_GL_PROGRAM(program, "void main() { gl_Position = vec4(0, 0, 0, 1); }",
                       "void main() { gl_FragColor = vec4(0, 1, 0, 1); }")
      glUseProgram(program.get());
      ASSERT_GL_NO_ERROR();
  
      // Having ref and mask the same for front and back is valid.
      glStencilMask(255);
      glStencilFunc(GL_ALWAYS, 0, 255);
      glDrawArrays(GL_TRIANGLES, 0, 6);
      ASSERT_GL_NO_ERROR();
  
      // Having a different front - back write mask generates an error.
      glStencilMaskSeparate(GL_FRONT, 1);
      glDrawArrays(GL_TRIANGLES, 0, 6);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Setting both write masks separately to the same value is valid.
      glStencilMaskSeparate(GL_BACK, 1);
      glDrawArrays(GL_TRIANGLES, 0, 6);
      ASSERT_GL_NO_ERROR();
  
      // Having a different stencil front - back mask generates an error
      glStencilFuncSeparate(GL_FRONT, GL_ALWAYS, 0, 1);
      glDrawArrays(GL_TRIANGLES, 0, 6);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Setting both masks separately to the same value is valid.
      glStencilFuncSeparate(GL_BACK, GL_ALWAYS, 0, 1);
      glDrawArrays(GL_TRIANGLES, 0, 6);
      ASSERT_GL_NO_ERROR();
  
      // Having a different stencil front - back reference generates an error
      glStencilFuncSeparate(GL_FRONT, GL_ALWAYS, 255, 1);
      glDrawArrays(GL_TRIANGLES, 0, 6);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Setting both references separately to the same value is valid.
      glStencilFuncSeparate(GL_BACK, GL_ALWAYS, 255, 1);
      glDrawArrays(GL_TRIANGLES, 0, 6);
      ASSERT_GL_NO_ERROR();
  
      // Using different stencil funcs, everything being equal is valid.
      glStencilFuncSeparate(GL_BACK, GL_NEVER, 255, 1);
      glDrawArrays(GL_TRIANGLES, 0, 6);
      ASSERT_GL_NO_ERROR();
  }
  
  // Test that GL_FIXED is forbidden
  TEST_P(WebGLCompatibilityTest, ForbidsGLFixed)
  {
      GLBuffer buffer;
      glBindBuffer(GL_ARRAY_BUFFER, buffer.get());
      glBufferData(GL_ARRAY_BUFFER, 16, nullptr, GL_STATIC_DRAW);
  
      glVertexAttribPointer(0, 1, GL_FLOAT, GL_FALSE, 0, nullptr);
      ASSERT_GL_NO_ERROR();
  
      glVertexAttribPointer(0, 1, GL_FIXED, GL_FALSE, 0, nullptr);
      EXPECT_GL_ERROR(GL_INVALID_ENUM);
  }
  
  // Test the WebGL limit of 255 for the attribute stride
  TEST_P(WebGLCompatibilityTest, MaxStride)
  {
      GLBuffer buffer;
      glBindBuffer(GL_ARRAY_BUFFER, buffer.get());
      glBufferData(GL_ARRAY_BUFFER, 1024, nullptr, GL_STATIC_DRAW);
  
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 255, nullptr);
      ASSERT_GL_NO_ERROR();
  
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 256, nullptr);
      EXPECT_GL_ERROR(GL_INVALID_VALUE);
  }
  
  // Test the checks for OOB reads in the vertex buffers, non-instanced version
  TEST_P(WebGLCompatibilityTest, DrawArraysBufferOutOfBoundsNonInstanced)
  {
      const std::string &vert =
          "attribute float a_pos;\n"
          "void main()\n"
          "{\n"
          "    gl_Position = vec4(a_pos, a_pos, a_pos, 1.0);\n"
          "}\n";
  
      const std::string &frag =
          "precision highp float;\n"
          "void main()\n"
          "{\n"
          "    gl_FragColor = vec4(1.0);\n"
          "}\n";
  
      ANGLE_GL_PROGRAM(program, vert, frag);
  
      GLint posLocation = glGetAttribLocation(program.get(), "a_pos");
      ASSERT_NE(-1, posLocation);
      glUseProgram(program.get());
  
      GLBuffer buffer;
      glBindBuffer(GL_ARRAY_BUFFER, buffer.get());
      glBufferData(GL_ARRAY_BUFFER, 16, nullptr, GL_STATIC_DRAW);
  
      glEnableVertexAttribArray(posLocation);
  
      const uint8_t* zeroOffset = nullptr;
  
      // Test touching the last element is valid.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 0, zeroOffset + 12);
      glDrawArrays(GL_POINTS, 0, 4);
      ASSERT_GL_NO_ERROR();
  
      // Test touching the last element + 1 is invalid.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 0, zeroOffset + 13);
      glDrawArrays(GL_POINTS, 0, 4);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Test touching the last element is valid, using a stride.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 2, zeroOffset + 9);
      glDrawArrays(GL_POINTS, 0, 4);
      ASSERT_GL_NO_ERROR();
  
      // Test touching the last element + 1 is invalid, using a stride.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 2, zeroOffset + 10);
      glDrawArrays(GL_POINTS, 0, 4);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Test any offset is valid if no vertices are drawn.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 0, zeroOffset + 32);
      glDrawArrays(GL_POINTS, 0, 0);
      ASSERT_GL_NO_ERROR();
  }
  
  // Test the checks for OOB reads in the index buffer
  TEST_P(WebGLCompatibilityTest, DrawElementsBufferOutOfBoundsInIndexBuffer)
  {
      const std::string &vert =
          "attribute float a_pos;\n"
          "void main()\n"
          "{\n"
          "    gl_Position = vec4(a_pos, a_pos, a_pos, 1.0);\n"
          "}\n";
  
      const std::string &frag =
          "precision highp float;\n"
          "void main()\n"
          "{\n"
          "    gl_FragColor = vec4(1.0);\n"
          "}\n";
  
      ANGLE_GL_PROGRAM(program, vert, frag);
  
      GLint posLocation = glGetAttribLocation(program.get(), "a_pos");
      ASSERT_NE(-1, posLocation);
      glUseProgram(program.get());
  
      GLBuffer vertexBuffer;
      glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer.get());
      glBufferData(GL_ARRAY_BUFFER, 16, nullptr, GL_STATIC_DRAW);
  
      glEnableVertexAttribArray(posLocation);
  
      const uint8_t *zeroOffset   = nullptr;
      const uint8_t zeroIndices[] = {0, 0, 0, 0, 0, 0, 0, 0};
  
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 0, zeroOffset);
  
      GLBuffer indexBuffer;
      glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer.get());
      glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(zeroIndices), zeroIndices, GL_STATIC_DRAW);
      ASSERT_GL_NO_ERROR();
  
      // Test touching the last index is valid
      glDrawElements(GL_POINTS, 4, GL_UNSIGNED_BYTE, zeroOffset + 4);
      ASSERT_GL_NO_ERROR();
  
      // Test touching the last + 1 element is invalid
      glDrawElements(GL_POINTS, 4, GL_UNSIGNED_BYTE, zeroOffset + 5);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Test any offset if valid if count is zero
      glDrawElements(GL_POINTS, 0, GL_UNSIGNED_BYTE, zeroOffset + 42);
      ASSERT_GL_NO_ERROR();
  
      // Test touching the first index is valid
      glDrawElements(GL_POINTS, 4, GL_UNSIGNED_BYTE, zeroOffset + 4);
      ASSERT_GL_NO_ERROR();
  
      // Test touching the first - 1 index is invalid
      // The error ha been specified to be INVALID_VALUE instead of INVALID_OPERATION because it was
      // the historic behavior of WebGL implementations
      glDrawElements(GL_POINTS, 4, GL_UNSIGNED_BYTE, zeroOffset - 1);
      EXPECT_GL_ERROR(GL_INVALID_VALUE);
  }
  
  // Test depth range with 'near' more or less than 'far.'
  TEST_P(WebGLCompatibilityTest, DepthRange)
  {
      glDepthRangef(0, 1);
      ASSERT_GL_NO_ERROR();
  
      glDepthRangef(.5, .5);
      ASSERT_GL_NO_ERROR();
  
      glDepthRangef(1, 0);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  }
  
  // Test all blend function combinations.
  // In WebGL it is invalid to combine constant color with constant alpha.
  TEST_P(WebGLCompatibilityTest, BlendWithConstantColor)
  {
      constexpr GLenum srcFunc[] = {
          GL_ZERO,
          GL_ONE,
          GL_SRC_COLOR,
          GL_ONE_MINUS_SRC_COLOR,
          GL_DST_COLOR,
          GL_ONE_MINUS_DST_COLOR,
          GL_SRC_ALPHA,
          GL_ONE_MINUS_SRC_ALPHA,
          GL_DST_ALPHA,
          GL_ONE_MINUS_DST_ALPHA,
          GL_CONSTANT_COLOR,
          GL_ONE_MINUS_CONSTANT_COLOR,
          GL_CONSTANT_ALPHA,
          GL_ONE_MINUS_CONSTANT_ALPHA,
          GL_SRC_ALPHA_SATURATE,
      };
  
      constexpr GLenum dstFunc[] = {
          GL_ZERO,           GL_ONE,
          GL_SRC_COLOR,      GL_ONE_MINUS_SRC_COLOR,
          GL_DST_COLOR,      GL_ONE_MINUS_DST_COLOR,
          GL_SRC_ALPHA,      GL_ONE_MINUS_SRC_ALPHA,
          GL_DST_ALPHA,      GL_ONE_MINUS_DST_ALPHA,
          GL_CONSTANT_COLOR, GL_ONE_MINUS_CONSTANT_COLOR,
          GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA,
      };
  
      for (GLenum src : srcFunc)
      {
          for (GLenum dst : dstFunc)
          {
              glBlendFunc(src, dst);
              CheckBlendFunctions(src, dst);
              glBlendFuncSeparate(src, dst, GL_ONE, GL_ONE);
              CheckBlendFunctions(src, dst);
          }
      }
  }
  
  // Test the checks for OOB reads in the vertex buffers, instanced version
  TEST_P(WebGL2CompatibilityTest, DrawArraysBufferOutOfBoundsInstanced)
  {
      const std::string &vert =
          "attribute float a_pos;\n"
          "void main()\n"
          "{\n"
          "    gl_Position = vec4(a_pos, a_pos, a_pos, 1.0);\n"
          "}\n";
  
      const std::string &frag =
          "precision highp float;\n"
          "void main()\n"
          "{\n"
          "    gl_FragColor = vec4(1.0);\n"
          "}\n";
  
      ANGLE_GL_PROGRAM(program, vert, frag);
  
      GLint posLocation = glGetAttribLocation(program.get(), "a_pos");
      ASSERT_NE(-1, posLocation);
      glUseProgram(program.get());
  
      GLBuffer buffer;
      glBindBuffer(GL_ARRAY_BUFFER, buffer.get());
      glBufferData(GL_ARRAY_BUFFER, 16, nullptr, GL_STATIC_DRAW);
  
      glEnableVertexAttribArray(posLocation);
      glVertexAttribDivisor(posLocation, 1);
  
      const uint8_t* zeroOffset = nullptr;
  
      // Test touching the last element is valid.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 0, zeroOffset + 12);
      glDrawArraysInstanced(GL_POINTS, 0, 1, 4);
      ASSERT_GL_NO_ERROR();
  
      // Test touching the last element + 1 is invalid.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 0, zeroOffset + 13);
      glDrawArraysInstanced(GL_POINTS, 0, 1, 4);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Test touching the last element is valid, using a stride.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 2, zeroOffset + 9);
      glDrawArraysInstanced(GL_POINTS, 0, 1, 4);
      ASSERT_GL_NO_ERROR();
  
      // Test touching the last element + 1 is invalid, using a stride.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 2, zeroOffset + 10);
      glDrawArraysInstanced(GL_POINTS, 0, 1, 4);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Test any offset is valid if no vertices are drawn.
      glVertexAttribPointer(0, 1, GL_UNSIGNED_BYTE, GL_FALSE, 0, zeroOffset + 32);
      glDrawArraysInstanced(GL_POINTS, 0, 1, 0);
      ASSERT_GL_NO_ERROR();
  }
  
  // Tests that NPOT is not enabled by default in WebGL 1 and that it can be enabled
  TEST_P(WebGLCompatibilityTest, NPOT)
  {
      EXPECT_FALSE(extensionEnabled("GL_OES_texture_npot"));
  
      // Create a texture and set an NPOT mip 0, should always be acceptable.
      GLTexture texture;
      glBindTexture(GL_TEXTURE_2D, texture.get());
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 10, 10, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      ASSERT_GL_NO_ERROR();
  
      // Try setting an NPOT mip 1 and verify the error if WebGL 1
      glTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA, 5, 5, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      if (getClientMajorVersion() < 3)
      {
          ASSERT_GL_ERROR(GL_INVALID_VALUE);
      }
      else
      {
          ASSERT_GL_NO_ERROR();
      }
  
      if (extensionRequestable("GL_OES_texture_npot"))
      {
          glRequestExtensionANGLE("GL_OES_texture_npot");
          ASSERT_GL_NO_ERROR();
  
          // Try again to set NPOT mip 1
          glTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA, 5, 5, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
          ASSERT_GL_NO_ERROR();
      }
  }
  
  template <typename T>
  void FillTexture2D(GLuint texture,
                     GLsizei width,
                     GLsizei height,
                     const T &onePixelData,
                     GLint level,
                     GLint internalFormat,
                     GLenum format,
                     GLenum type)
  {
      std::vector<T> allPixelsData(width * height, onePixelData);
  
      glBindTexture(GL_TEXTURE_2D, texture);
      glTexImage2D(GL_TEXTURE_2D, level, internalFormat, width, height, 0, format, type,
                   allPixelsData.data());
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  }
  
  // Test that unset gl_Position defaults to (0,0,0,0).
  TEST_P(WebGLCompatibilityTest, DefaultPosition)
  {
      // Draw a quad where each vertex is red if gl_Position is (0,0,0,0) before it is set,
      // and green otherwise.  The center of each quadrant will be red if and only if all
      // four corners are red.
      const std::string vertexShader =
          "attribute vec3 pos;\n"
          "varying vec4 color;\n"
          "void main() {\n"
          "    if (gl_Position == vec4(0,0,0,0)) {\n"
          "        color = vec4(1,0,0,1);\n"
          "    } else {\n"
          "        color = vec4(0,1,0,1);\n"
          "    }\n"
          "    gl_Position = vec4(pos,1);\n"
          "}\n";
  
      const std::string fragmentShader =
          "precision mediump float;\n"
          "varying vec4 color;\n"
          "void main() {\n"
          "    gl_FragColor = color;\n"
          "}\n";
  
      ANGLE_GL_PROGRAM(program, vertexShader, fragmentShader);
      drawQuad(program.get(), "pos", 0.0f, 1.0f, true);
      EXPECT_PIXEL_COLOR_EQ(getWindowWidth() * 1 / 4, getWindowHeight() * 1 / 4, GLColor::red);
      EXPECT_PIXEL_COLOR_EQ(getWindowWidth() * 1 / 4, getWindowHeight() * 3 / 4, GLColor::red);
      EXPECT_PIXEL_COLOR_EQ(getWindowWidth() * 3 / 4, getWindowHeight() * 1 / 4, GLColor::red);
      EXPECT_PIXEL_COLOR_EQ(getWindowWidth() * 3 / 4, getWindowHeight() * 3 / 4, GLColor::red);
  }
  
  // Tests that a rendering feedback loop triggers a GL error under WebGL.
  // Based on WebGL test conformance/renderbuffers/feedback-loop.html.
  TEST_P(WebGLCompatibilityTest, RenderingFeedbackLoop)
  {
      const std::string vertexShader =
          "attribute vec4 a_position;\n"
          "varying vec2 v_texCoord;\n"
          "void main() {\n"
          "    gl_Position = a_position;\n"
          "    v_texCoord = (a_position.xy * 0.5) + 0.5;\n"
          "}\n";
  
      const std::string fragmentShader =
          "precision mediump float;\n"
          "varying vec2 v_texCoord;\n"
          "uniform sampler2D u_texture;\n"
          "void main() {\n"
          "    // Shader swizzles color channels so we can tell if the draw succeeded.\n"
          "    gl_FragColor = texture2D(u_texture, v_texCoord).gbra;\n"
          "}\n";
  
      GLTexture texture;
      FillTexture2D(texture.get(), 1, 1, GLColor::red, 0, GL_RGBA, GL_RGBA, GL_UNSIGNED_BYTE);
  
      ASSERT_GL_NO_ERROR();
  
      GLFramebuffer framebuffer;
      glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get());
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture.get(), 0);
  
      ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));
  
      ANGLE_GL_PROGRAM(program, vertexShader, fragmentShader);
  
      GLint uniformLoc = glGetUniformLocation(program.get(), "u_texture");
      ASSERT_NE(-1, uniformLoc);
  
      glUseProgram(program.get());
      glUniform1i(uniformLoc, 0);
      glDisable(GL_BLEND);
      glDisable(GL_DEPTH_TEST);
      ASSERT_GL_NO_ERROR();
  
      // Drawing with a texture that is also bound to the current framebuffer should fail
      glBindTexture(GL_TEXTURE_2D, texture.get());
      drawQuad(program.get(), "a_position", 0.5f, 1.0f, true);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Ensure that the texture contents did not change after the previous render
      glBindFramebuffer(GL_FRAMEBUFFER, 0);
      drawQuad(program.get(), "a_position", 0.5f, 1.0f, true);
      ASSERT_GL_NO_ERROR();
      EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::blue);
  
      // Drawing when texture is bound to an inactive uniform should succeed
      GLTexture texture2;
      FillTexture2D(texture2.get(), 1, 1, GLColor::green, 0, GL_RGBA, GL_RGBA, GL_UNSIGNED_BYTE);
  
      glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get());
      glActiveTexture(GL_TEXTURE1);
      glBindTexture(GL_TEXTURE_2D, texture.get());
      drawQuad(program.get(), "a_position", 0.5f, 1.0f, true);
      ASSERT_GL_NO_ERROR();
      EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
  }
  
  // Test for the max draw buffers and color attachments.
  TEST_P(WebGLCompatibilityTest, MaxDrawBuffersAttachmentPoints)
  {
      // This test only applies to ES2.
      if (getClientMajorVersion() != 2)
      {
          return;
      }
  
      GLFramebuffer fbo[2];
      glBindFramebuffer(GL_FRAMEBUFFER, fbo[0].get());
  
      // Test that is valid when we bind with a single attachment point.
      GLTexture texture;
      glBindTexture(GL_TEXTURE_2D, texture.get());
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture.get(), 0);
      ASSERT_GL_NO_ERROR();
  
      // Test that enabling the draw buffers extension will allow us to bind with a non-zero
      // attachment point.
      if (extensionRequestable("GL_EXT_draw_buffers"))
      {
          glRequestExtensionANGLE("GL_EXT_draw_buffers");
          EXPECT_GL_NO_ERROR();
          EXPECT_TRUE(extensionEnabled("GL_EXT_draw_buffers"));
  
          glBindFramebuffer(GL_FRAMEBUFFER, fbo[1].get());
  
          GLTexture texture2;
          glBindTexture(GL_TEXTURE_2D, texture2.get());
          glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
          glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, texture2.get(),
                                 0);
          ASSERT_GL_NO_ERROR();
      }
  }
  
  // Test that the offset in the index buffer is forced to be a multiple of the element size
  TEST_P(WebGLCompatibilityTest, DrawElementsOffsetRestriction)
  {
      const std::string &vert =
          "attribute vec3 a_pos;\n"
          "void main()\n"
          "{\n"
          "    gl_Position = vec4(a_pos, 1.0);\n"
          "}\n";
  
      const std::string &frag =
          "precision highp float;\n"
          "void main()\n"
          "{\n"
          "    gl_FragColor = vec4(1.0);\n"
          "}\n";
  
      ANGLE_GL_PROGRAM(program, vert, frag);
  
      GLint posLocation = glGetAttribLocation(program.get(), "a_pos");
      ASSERT_NE(-1, posLocation);
      glUseProgram(program.get());
  
      const auto &vertices = GetQuadVertices();
  
      GLBuffer vertexBuffer;
      glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer.get());
      glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                   GL_STATIC_DRAW);
  
      glVertexAttribPointer(posLocation, 3, GL_FLOAT, GL_FALSE, 0, 0);
      glEnableVertexAttribArray(posLocation);
  
      GLBuffer indexBuffer;
      const GLubyte indices[] = {0, 0, 0, 0, 0, 0, 0};
      glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer.get());
      glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
  
      ASSERT_GL_NO_ERROR();
  
      const char *zeroIndices = nullptr;
  
      glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, zeroIndices);
      ASSERT_GL_NO_ERROR();
  
      glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, zeroIndices);
      ASSERT_GL_NO_ERROR();
  
      glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, zeroIndices + 1);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  }
  
  // Test that the offset and stride in the vertex buffer is forced to be a multiple of the element
  // size
  TEST_P(WebGLCompatibilityTest, VertexAttribPointerOffsetRestriction)
  {
      const char *zeroOffset = nullptr;
  
      // Base case, vector of two floats
      glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, zeroOffset);
      ASSERT_GL_NO_ERROR();
  
      // Test setting a non-multiple offset
      glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, zeroOffset + 1);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
      glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, zeroOffset + 2);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
      glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, zeroOffset + 3);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // Test setting a non-multiple stride
      glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 1, zeroOffset);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
      glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2, zeroOffset);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
      glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 3, zeroOffset);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  }
  
  void WebGLCompatibilityTest::drawBuffersEXTFeedbackLoop(GLuint program,
                                                          const std::array<GLenum, 2> &drawBuffers,
                                                          GLenum expectedError)
  {
      glDrawBuffersEXT(2, drawBuffers.data());
  
      // Make sure framebuffer is complete before feedback loop detection
      ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));
  
      drawQuad(program, "aPosition", 0.5f, 1.0f, true);
  
      // "Rendering to a texture where it samples from should geneates INVALID_OPERATION. Otherwise,
      // it should be NO_ERROR"
      EXPECT_GL_ERROR(expectedError);
  }
  
  // This tests that rendering feedback loops works as expected with GL_EXT_draw_buffers.
  // Based on WebGL test conformance/extensions/webgl-draw-buffers-feedback-loop.html
  TEST_P(WebGLCompatibilityTest, RenderingFeedbackLoopWithDrawBuffersEXT)
  {
      const std::string vertexShader =
          "attribute vec4 aPosition;\n"
          "varying vec2 texCoord;\n"
          "void main() {\n"
          "    gl_Position = aPosition;\n"
          "    texCoord = (aPosition.xy * 0.5) + 0.5;\n"
          "}\n";
  
      const std::string fragmentShader =
          "#extension GL_EXT_draw_buffers : require\n"
          "precision mediump float;\n"
          "uniform sampler2D tex;\n"
          "varying vec2 texCoord;\n"
          "void main() {\n"
          "    gl_FragData[0] = texture2D(tex, texCoord);\n"
          "    gl_FragData[1] = texture2D(tex, texCoord);\n"
          "}\n";
  
      GLsizei width  = 8;
      GLsizei height = 8;
  
      // This shader cannot be run in ES3, because WebGL 2 does not expose the draw buffers
      // extension and gl_FragData semantics are changed to enforce indexing by zero always.
      // TODO(jmadill): This extension should be disabled in WebGL 2 contexts.
      if (/*!extensionEnabled("GL_EXT_draw_buffers")*/ getClientMajorVersion() != 2)
      {
          // No WEBGL_draw_buffers support -- this is legal.
          return;
      }
  
      GLint maxDrawBuffers = 0;
      glGetIntegerv(GL_MAX_DRAW_BUFFERS, &maxDrawBuffers);
  
      if (maxDrawBuffers < 2)
      {
          std::cout << "Test skipped because MAX_DRAW_BUFFERS is too small." << std::endl;
          return;
      }
  
      ANGLE_GL_PROGRAM(program, vertexShader, fragmentShader);
      glUseProgram(program.get());
      glViewport(0, 0, width, height);
  
      GLTexture tex0;
      GLTexture tex1;
      GLFramebuffer fbo;
      FillTexture2D(tex0.get(), width, height, GLColor::red, 0, GL_RGBA, GL_RGBA, GL_UNSIGNED_BYTE);
      FillTexture2D(tex1.get(), width, height, GLColor::green, 0, GL_RGBA, GL_RGBA, GL_UNSIGNED_BYTE);
      ASSERT_GL_NO_ERROR();
  
      glBindTexture(GL_TEXTURE_2D, tex1.get());
      GLint texLoc = glGetUniformLocation(program.get(), "tex");
      ASSERT_NE(-1, texLoc);
      glUniform1i(texLoc, 0);
      ASSERT_GL_NO_ERROR();
  
      // The sampling texture is bound to COLOR_ATTACHMENT1 during resource allocation
      glBindFramebuffer(GL_FRAMEBUFFER, fbo.get());
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex0.get(), 0);
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, tex1.get(), 0);
  
      drawBuffersEXTFeedbackLoop(program.get(), {{GL_NONE, GL_COLOR_ATTACHMENT1}},
                                 GL_INVALID_OPERATION);
      drawBuffersEXTFeedbackLoop(program.get(), {{GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1}},
                                 GL_INVALID_OPERATION);
      drawBuffersEXTFeedbackLoop(program.get(), {{GL_COLOR_ATTACHMENT0, GL_NONE}}, GL_NO_ERROR);
  }
  
  // Test tests that texture copying feedback loops are properly rejected in WebGL.
  // Based on the WebGL test conformance/textures/misc/texture-copying-feedback-loops.html
  TEST_P(WebGLCompatibilityTest, TextureCopyingFeedbackLoops)
  {
      GLTexture texture;
      glBindTexture(GL_TEXTURE_2D, texture.get());
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  
      GLTexture texture2;
      glBindTexture(GL_TEXTURE_2D, texture2.get());
      glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  
      GLFramebuffer framebuffer;
      glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get());
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture.get(), 0);
  
      // framebuffer should be FRAMEBUFFER_COMPLETE.
      ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));
      ASSERT_GL_NO_ERROR();
  
      // testing copyTexImage2D
  
      // copyTexImage2D to same texture but different level
      glBindTexture(GL_TEXTURE_2D, texture.get());
      glCopyTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA, 0, 0, 2, 2, 0);
      EXPECT_GL_NO_ERROR();
  
      // copyTexImage2D to same texture same level, invalid feedback loop
      glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 0, 0, 2, 2, 0);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // copyTexImage2D to different texture
      glBindTexture(GL_TEXTURE_2D, texture2.get());
      glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 0, 0, 2, 2, 0);
      EXPECT_GL_NO_ERROR();
  
      // testing copyTexSubImage2D
  
      // copyTexSubImage2D to same texture but different level
      glBindTexture(GL_TEXTURE_2D, texture.get());
      glCopyTexSubImage2D(GL_TEXTURE_2D, 1, 0, 0, 0, 0, 1, 1);
      EXPECT_GL_NO_ERROR();
  
      // copyTexSubImage2D to same texture same level, invalid feedback loop
      glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, 1, 1);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // copyTexSubImage2D to different texture
      glBindTexture(GL_TEXTURE_2D, texture2.get());
      glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, 1, 1);
      EXPECT_GL_NO_ERROR();
  }
  
  void WebGLCompatibilityTest::drawBuffersFeedbackLoop(GLuint program,
                                                       const std::array<GLenum, 2> &drawBuffers,
                                                       GLenum expectedError)
  {
      glDrawBuffers(2, drawBuffers.data());
  
      // Make sure framebuffer is complete before feedback loop detection
      ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));
  
      drawQuad(program, "aPosition", 0.5f, 1.0f, true);
  
      // "Rendering to a texture where it samples from should geneates INVALID_OPERATION. Otherwise,
      // it should be NO_ERROR"
      EXPECT_GL_ERROR(expectedError);
  }
  
  // Tests invariance matching rules between built in varyings.
  // Based on WebGL test conformance/glsl/misc/shaders-with-invariance.html.
  TEST_P(WebGLCompatibilityTest, BuiltInInvariant)
  {
      const std::string vertexShaderVariant =
          "varying vec4 v_varying;\n"
          "void main()\n"
          "{\n"
          "    gl_PointSize = 1.0;\n"
          "    gl_Position = v_varying;\n"
          "}";
      const std::string fragmentShaderInvariantGlFragCoord =
          "invariant gl_FragCoord;\n"
          "void main()\n"
          "{\n"
          "    gl_FragColor = gl_FragCoord;\n"
          "}";
      const std::string fragmentShaderInvariantGlPointCoord =
          "invariant gl_PointCoord;\n"
          "void main()\n"
          "{\n"
          "    gl_FragColor = vec4(gl_PointCoord, 0.0, 0.0);\n"
          "}";
  
      GLuint program = CompileProgram(vertexShaderVariant, fragmentShaderInvariantGlFragCoord);
      EXPECT_EQ(0u, program);
  
      program = CompileProgram(vertexShaderVariant, fragmentShaderInvariantGlPointCoord);
      EXPECT_EQ(0u, program);
  }
  
  // This tests that rendering feedback loops works as expected with WebGL 2.
  // Based on WebGL test conformance2/rendering/rendering-sampling-feedback-loop.html
  TEST_P(WebGL2CompatibilityTest, RenderingFeedbackLoopWithDrawBuffers)
  {
      const std::string vertexShader =
          "#version 300 es\n"
          "in vec4 aPosition;\n"
          "out vec2 texCoord;\n"
          "void main() {\n"
          "    gl_Position = aPosition;\n"
          "    texCoord = (aPosition.xy * 0.5) + 0.5;\n"
          "}\n";
  
      const std::string fragmentShader =
          "#version 300 es\n"
          "precision mediump float;\n"
          "uniform sampler2D tex;\n"
          "in vec2 texCoord;\n"
          "out vec4 oColor;\n"
          "void main() {\n"
          "    oColor = texture(tex, texCoord);\n"
          "}\n";
  
      GLsizei width  = 8;
      GLsizei height = 8;
  
      GLint maxDrawBuffers = 0;
      glGetIntegerv(GL_MAX_DRAW_BUFFERS, &maxDrawBuffers);
      // ES3 requires a minimum value of 4 for MAX_DRAW_BUFFERS.
      ASSERT_GE(maxDrawBuffers, 2);
  
      ANGLE_GL_PROGRAM(program, vertexShader, fragmentShader);
      glUseProgram(program.get());
      glViewport(0, 0, width, height);
  
      GLTexture tex0;
      GLTexture tex1;
      GLFramebuffer fbo;
      FillTexture2D(tex0.get(), width, height, GLColor::red, 0, GL_RGBA, GL_RGBA, GL_UNSIGNED_BYTE);
      FillTexture2D(tex1.get(), width, height, GLColor::green, 0, GL_RGBA, GL_RGBA, GL_UNSIGNED_BYTE);
      ASSERT_GL_NO_ERROR();
  
      glBindTexture(GL_TEXTURE_2D, tex1.get());
      GLint texLoc = glGetUniformLocation(program.get(), "tex");
      ASSERT_NE(-1, texLoc);
      glUniform1i(texLoc, 0);
  
      // The sampling texture is bound to COLOR_ATTACHMENT1 during resource allocation
      glBindFramebuffer(GL_FRAMEBUFFER, fbo.get());
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex0.get(), 0);
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, tex1.get(), 0);
      ASSERT_GL_NO_ERROR();
  
      drawBuffersFeedbackLoop(program.get(), {{GL_NONE, GL_COLOR_ATTACHMENT1}}, GL_INVALID_OPERATION);
      drawBuffersFeedbackLoop(program.get(), {{GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1}},
                              GL_INVALID_OPERATION);
      drawBuffersFeedbackLoop(program.get(), {{GL_COLOR_ATTACHMENT0, GL_NONE}}, GL_NO_ERROR);
  }
  
  // This test covers detection of rendering feedback loops between the FBO and a depth Texture.
  // Based on WebGL test conformance2/rendering/depth-stencil-feedback-loop.html
  TEST_P(WebGL2CompatibilityTest, RenderingFeedbackLoopWithDepthStencil)
  {
      const std::string vertexShader =
          "#version 300 es\n"
          "in vec4 aPosition;\n"
          "out vec2 texCoord;\n"
          "void main() {\n"
          "    gl_Position = aPosition;\n"
          "    texCoord = (aPosition.xy * 0.5) + 0.5;\n"
          "}\n";
  
      const std::string fragmentShader =
          "#version 300 es\n"
          "precision mediump float;\n"
          "uniform sampler2D tex;\n"
          "in vec2 texCoord;\n"
          "out vec4 oColor;\n"
          "void main() {\n"
          "    oColor = texture(tex, texCoord);\n"
          "}\n";
  
      GLsizei width  = 8;
      GLsizei height = 8;
  
      ANGLE_GL_PROGRAM(program, vertexShader, fragmentShader);
      glUseProgram(program.get());
  
      glViewport(0, 0, width, height);
  
      GLint texLoc = glGetUniformLocation(program.get(), "tex");
      glUniform1i(texLoc, 0);
  
      // Create textures and allocate storage
      GLTexture tex0;
      GLTexture tex1;
      GLRenderbuffer rb;
      FillTexture2D(tex0.get(), width, height, GLColor::black, 0, GL_RGBA, GL_RGBA, GL_UNSIGNED_BYTE);
      FillTexture2D(tex1.get(), width, height, 0x80, 0, GL_DEPTH_COMPONENT16, GL_DEPTH_COMPONENT,
                    GL_UNSIGNED_INT);
      glBindRenderbuffer(GL_RENDERBUFFER, rb.get());
      glRenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX8, width, height);
      ASSERT_GL_NO_ERROR();
  
      GLFramebuffer fbo;
      glBindFramebuffer(GL_FRAMEBUFFER, fbo.get());
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex0.get(), 0);
  
      // Test rendering and sampling feedback loop for depth buffer
      glBindTexture(GL_TEXTURE_2D, tex1.get());
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, tex1.get(), 0);
      ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));
  
      // The same image is used as depth buffer during rendering.
      glEnable(GL_DEPTH_TEST);
      drawQuad(program.get(), "aPosition", 0.5f, 1.0f, true);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // The same image is used as depth buffer. But depth mask is false.
      glDepthMask(GL_FALSE);
      drawQuad(program.get(), "aPosition", 0.5f, 1.0f, true);
      EXPECT_GL_NO_ERROR();
  
      // The same image is used as depth buffer. But depth test is not enabled during rendering.
      glDepthMask(GL_TRUE);
      glDisable(GL_DEPTH_TEST);
      drawQuad(program.get(), "aPosition", 0.5f, 1.0f, true);
      EXPECT_GL_NO_ERROR();
  
      // Test rendering and sampling feedback loop for stencil buffer
      glBindTexture(GL_RENDERBUFFER, rb.get());
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, 0, 0);
      glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rb.get());
      ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));
      constexpr GLint stencilClearValue = 0x40;
      glClearBufferiv(GL_STENCIL, 0, &stencilClearValue);
  
      // The same image is used as stencil buffer during rendering.
      glEnable(GL_STENCIL_TEST);
      drawQuad(program.get(), "aPosition", 0.5f, 1.0f, true);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  
      // The same image is used as stencil buffer. But stencil mask is zero.
      glStencilMask(0x0);
      drawQuad(program.get(), "aPosition", 0.5f, 1.0f, true);
      EXPECT_GL_NO_ERROR();
  
      // The same image is used as stencil buffer. But stencil test is not enabled during rendering.
      glStencilMask(0xffff);
      glDisable(GL_STENCIL_TEST);
      drawQuad(program.get(), "aPosition", 0.5f, 1.0f, true);
      EXPECT_GL_NO_ERROR();
  }
  
  // The source and the target for CopyTexSubImage3D are the same 3D texture.
  // But the level of the 3D texture != the level of the read attachment.
  TEST_P(WebGL2CompatibilityTest, NoTextureCopyingFeedbackLoopBetween3DLevels)
  {
      GLTexture texture;
      GLFramebuffer framebuffer;
  
      glBindTexture(GL_TEXTURE_3D, texture.get());
      glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get());
  
      glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA8, 2, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glTexImage3D(GL_TEXTURE_3D, 1, GL_RGBA8, 2, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, texture.get(), 0, 0);
      ASSERT_GL_NO_ERROR();
  
      glCopyTexSubImage3D(GL_TEXTURE_3D, 1, 0, 0, 0, 0, 0, 2, 2);
      EXPECT_GL_NO_ERROR();
  }
  
  // The source and the target for CopyTexSubImage3D are the same 3D texture.
  // But the zoffset of the 3D texture != the layer of the read attachment.
  TEST_P(WebGL2CompatibilityTest, NoTextureCopyingFeedbackLoopBetween3DLayers)
  {
      GLTexture texture;
      GLFramebuffer framebuffer;
  
      glBindTexture(GL_TEXTURE_3D, texture.get());
      glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get());
  
      glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA8, 2, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, texture.get(), 0, 1);
      ASSERT_GL_NO_ERROR();
  
      glCopyTexSubImage3D(GL_TEXTURE_3D, 0, 0, 0, 0, 0, 0, 2, 2);
      EXPECT_GL_NO_ERROR();
  }
  
  // The source and the target for CopyTexSubImage3D are the same 3D texture.
  // And the level / zoffset of the 3D texture is equal to the level / layer of the read attachment.
  TEST_P(WebGL2CompatibilityTest, TextureCopyingFeedbackLoop3D)
  {
      GLTexture texture;
      GLFramebuffer framebuffer;
  
      glBindTexture(GL_TEXTURE_3D, texture.get());
      glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get());
  
      glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA8, 4, 4, 4, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glTexImage3D(GL_TEXTURE_3D, 1, GL_RGBA8, 2, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glTexImage3D(GL_TEXTURE_3D, 2, GL_RGBA8, 1, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, texture.get(), 1, 0);
      ASSERT_GL_NO_ERROR();
  
      glCopyTexSubImage3D(GL_TEXTURE_3D, 1, 0, 0, 0, 0, 0, 2, 2);
      EXPECT_GL_ERROR(GL_INVALID_OPERATION);
  }
  
  // Use this to select which configurations (e.g. which renderer, which GLES major version) these
  // tests should be run against.
  ANGLE_INSTANTIATE_TEST(WebGLCompatibilityTest,
                         ES2_D3D9(),
                         ES2_D3D11(),
                         ES3_D3D11(),
                         ES2_D3D11_FL9_3(),
                         ES2_OPENGL(),
                         ES3_OPENGL(),
                         ES2_OPENGLES(),
                         ES3_OPENGLES());
  
  ANGLE_INSTANTIATE_TEST(WebGL2CompatibilityTest, ES3_D3D11(), ES3_OPENGL(), ES3_OPENGLES());
  }  // namespace