MultipleDrawBuffers.cpp

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Author : Stuart Morgan
Date : 2019-08-14 12:25:12
Hash : 9d737966
Message : Standardize copyright notices to project style For all "ANGLE Project" copyrights, standardize to the format specified by the style guide. Changes: - "Copyright (c)" and "Copyright(c)" changed to just "Copyright". - Removed the second half of date ranges ("Y1Y1-Y2Y2"->"Y1Y1"). - Fixed a small number of files that had no copyright date using the initial commit year from the version control history. - Fixed one instance of copyright being "The ANGLE Project" rather than "The ANGLE Project Authors" These changes are applied both to the copyright of source file, and where applicable to copyright statements that are generated by templates. BUG=angleproject:3811 Change-Id: I973dd65e4ef9deeba232d5be74c768256a0eb2e5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1754397 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

samples/multiple_draw_buffers/MultipleDrawBuffers.cpp

//
// Copyright 2014 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.
//

//            Based on Simple_Texture2D.c from
// Book:      OpenGL(R) ES 2.0 Programming Guide
// Authors:   Aaftab Munshi, Dan Ginsburg, Dave Shreiner
// ISBN-10:   0321502795
// ISBN-13:   9780321502797
// Publisher: Addison-Wesley Professional
// URLs:      http://safari.informit.com/9780321563835
//            http://www.opengles-book.com

#include "SampleApplication.h"

#include "texture_utils.h"
#include "util/shader_utils.h"
#include "util/system_utils.h"

#include <cstring>
#include <iostream>

class MultipleDrawBuffersSample : public SampleApplication
{
  public:
    MultipleDrawBuffersSample(int argc, char **argv)
        : SampleApplication("MultipleDrawBuffers", argc, argv)
    {}

    virtual bool initialize()
    {
        // Check EXT_draw_buffers is supported
        char *extensionString = (char *)glGetString(GL_EXTENSIONS);
        if (strstr(extensionString, "GL_EXT_draw_buffers") != nullptr)
        {
            // Retrieve the address of glDrawBuffersEXT from EGL
            mDrawBuffers = (PFNGLDRAWBUFFERSEXTPROC)eglGetProcAddress("glDrawBuffersEXT");
        }
        else
        {
            mDrawBuffers = glDrawBuffers;
        }

        if (!mDrawBuffers)
        {
            std::cerr << "Unable to load glDrawBuffers[EXT] entry point.";
            return false;
        }

        std::stringstream vsStream;
        vsStream << angle::GetExecutableDirectory() << "/multiple_draw_buffers_vs.glsl";

        std::stringstream fsStream;
        fsStream << angle::GetExecutableDirectory() << "/multiple_draw_buffers_fs.glsl";

        std::stringstream copyFsStream;
        fsStream << angle::GetExecutableDirectory() << "/multiple_draw_buffers_copy_fs.glsl";

        mMRTProgram = CompileProgramFromFiles(vsStream.str(), fsStream.str());
        if (!mMRTProgram)
        {
            return false;
        }

        mCopyProgram = CompileProgramFromFiles(vsStream.str(), copyFsStream.str());
        if (!mCopyProgram)
        {
            return false;
        }

        // Get the attribute locations
        mPositionLoc = glGetAttribLocation(mCopyProgram, "a_position");
        mTexCoordLoc = glGetAttribLocation(mCopyProgram, "a_texCoord");

        // Get the sampler location
        mSamplerLoc = glGetUniformLocation(mCopyProgram, "s_texture");

        // Load the texture
        mTexture = CreateSimpleTexture2D();

        // Initialize the user framebuffer
        glGenFramebuffers(1, &mFramebuffer);
        glGenTextures(mFramebufferAttachmentCount, mFramebufferTextures);

        glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
        for (size_t i = 0; i < mFramebufferAttachmentCount; i++)
        {
            // Create textures for the four color attachments
            glBindTexture(GL_TEXTURE_2D, mFramebufferTextures[i]);
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, getWindow()->getWidth(),
                         getWindow()->getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
            glFramebufferTexture2D(GL_FRAMEBUFFER,
                                   static_cast<GLenum>(GL_COLOR_ATTACHMENT0_EXT + i), GL_TEXTURE_2D,
                                   mFramebufferTextures[i], 0);
        }

        glBindTexture(GL_TEXTURE_2D, 0);

        glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

        return true;
    }

    virtual void destroy()
    {
        glDeleteProgram(mCopyProgram);
        glDeleteProgram(mMRTProgram);
        glDeleteTextures(1, &mTexture);
        glDeleteTextures(mFramebufferAttachmentCount, mFramebufferTextures);
        glDeleteFramebuffers(1, &mFramebuffer);
    }

    virtual void draw()
    {
        GLfloat vertices[] = {
            -0.8f, 0.8f,  0.0f,  // Position 0
            0.0f,  0.0f,         // TexCoord 0
            -0.8f, -0.8f, 0.0f,  // Position 1
            0.0f,  1.0f,         // TexCoord 1
            0.8f,  -0.8f, 0.0f,  // Position 2
            1.0f,  1.0f,         // TexCoord 2
            0.8f,  0.8f,  0.0f,  // Position 3
            1.0f,  0.0f          // TexCoord 3
        };
        GLushort indices[]                              = {0, 1, 2, 0, 2, 3};
        GLenum drawBuffers[mFramebufferAttachmentCount] = {
            GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_COLOR_ATTACHMENT2_EXT,
            GL_COLOR_ATTACHMENT3_EXT};

        // Enable drawing to the four color attachments of the user framebuffer
        glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
        mDrawBuffers(mFramebufferAttachmentCount, drawBuffers);

        // Set the viewport
        GLint width  = static_cast<GLint>(getWindow()->getWidth());
        GLint height = static_cast<GLint>(getWindow()->getHeight());
        glViewport(0, 0, width, height);

        // Clear the color buffer
        glClear(GL_COLOR_BUFFER_BIT);

        // Use the program object
        glUseProgram(mMRTProgram);

        // Load the vertex position
        glVertexAttribPointer(mPositionLoc, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), vertices);
        glEnableVertexAttribArray(mPositionLoc);

        // Load the texture coordinate
        glVertexAttribPointer(mTexCoordLoc, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat),
                              vertices + 3);
        glEnableVertexAttribArray(mTexCoordLoc);

        // Bind the texture
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, mTexture);

        // Set the sampler texture unit to 0
        glUniform1i(mSamplerLoc, 0);

        // Draw the textured quad to the four render targets
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);

        // Enable the default framebuffer and single textured drawing
        glBindFramebuffer(GL_FRAMEBUFFER, 0);
        glUseProgram(mCopyProgram);

        // Draw the four textured quads to a separate region in the viewport
        glBindTexture(GL_TEXTURE_2D, mFramebufferTextures[0]);
        glViewport(0, 0, width / 2, height / 2);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);

        glBindTexture(GL_TEXTURE_2D, mFramebufferTextures[1]);
        glViewport(width / 2, 0, width / 2, height / 2);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);

        glBindTexture(GL_TEXTURE_2D, mFramebufferTextures[2]);
        glViewport(0, height / 2, width / 2, height / 2);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);

        glBindTexture(GL_TEXTURE_2D, mFramebufferTextures[3]);
        glViewport(width / 2, height / 2, width / 2, height / 2);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices);
    }

  private:
    // Handle to a program object
    GLuint mMRTProgram;
    GLuint mCopyProgram;

    // Attribute locations
    GLint mPositionLoc;
    GLint mTexCoordLoc;

    // Sampler location
    GLint mSamplerLoc;

    // Texture handle
    GLuint mTexture;

    // Framebuffer object handle
    GLuint mFramebuffer;

    // Framebuffer color attachments
    static const size_t mFramebufferAttachmentCount = 4;
    GLuint mFramebufferTextures[mFramebufferAttachmentCount];

    // Loaded draw buffer entry points
    PFNGLDRAWBUFFERSEXTPROC mDrawBuffers;
};

int main(int argc, char **argv)
{
    MultipleDrawBuffersSample app(argc, argv);
    return app.run();
}

kc3-lang/angle/samples/multiple_draw_buffers/MultipleDrawBuffers.cpp

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kc3-lang/angle /samples/multiple_draw_buffers/MultipleDrawBuffers.cpp