Commit d23d9c88e5166ae62f7592c71d7c6a5115666526
2014-07-07T23:26:34
Fixed bug 2421 - SDL_RenderCopyEx off by one when rotating by 90 and -90 chasesan When using SDL_RenderCopyEx, I get a problem on some platforms where the output is offset by +/-1 on other platforms and not on others. I tried it with a center of both 0,0 (and offsetting by width/height) and NULL (for centered). The rotation involved is 90, and/or -90 rotation. The rotation was a constant, no arithmetic was involved when inputting it into SDL_RenderCopyEx. This occurred with 32x32, 24x24, and 16x16 texture sizes. I apologize that I don't have more precise information, as I received the information as a bug report myself. But I have tracked the problem down to here. My program requires pixel perfect alignment on several different platforms, so this is something of a showstopper for me. -- Sylvain It appears the RenderCopyEx is done as expected, this is the red rectangle which is not correctly positionned ! So, here's patch with a 0.5 float increment, like for opengles2, for DrawLines, and also Draw Points.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
diff --git a/src/render/opengles/SDL_render_gles.c b/src/render/opengles/SDL_render_gles.c
index 90a485b..72cce30 100644
--- a/src/render/opengles/SDL_render_gles.c
+++ b/src/render/opengles/SDL_render_gles.c
@@ -814,12 +814,24 @@ GLES_RenderDrawPoints(SDL_Renderer * renderer, const SDL_FPoint * points,
int count)
{
GLES_RenderData *data = (GLES_RenderData *) renderer->driverdata;
+ GLfloat *vertices;
+ int idx;
GLES_SetDrawingState(renderer);
- data->glVertexPointer(2, GL_FLOAT, 0, points);
- data->glDrawArrays(GL_POINTS, 0, count);
+ /* Emit the specified vertices as points */
+ vertices = SDL_stack_alloc(GLfloat, count * 2);
+ for (idx = 0; idx < count; ++idx) {
+ GLfloat x = points[idx].x + 0.5f;
+ GLfloat y = points[idx].y + 0.5f;
+
+ vertices[idx * 2] = x;
+ vertices[(idx * 2) + 1] = y;
+ }
+ data->glVertexPointer(2, GL_FLOAT, 0, vertices);
+ data->glDrawArrays(GL_POINTS, 0, count);
+ SDL_stack_free(vertices);
return 0;
}
@@ -828,10 +840,22 @@ GLES_RenderDrawLines(SDL_Renderer * renderer, const SDL_FPoint * points,
int count)
{
GLES_RenderData *data = (GLES_RenderData *) renderer->driverdata;
+ GLfloat *vertices;
+ int idx;
GLES_SetDrawingState(renderer);
- data->glVertexPointer(2, GL_FLOAT, 0, points);
+ /* Emit a line strip including the specified vertices */
+ vertices = SDL_stack_alloc(GLfloat, count * 2);
+ for (idx = 0; idx < count; ++idx) {
+ GLfloat x = points[idx].x + 0.5f;
+ GLfloat y = points[idx].y + 0.5f;
+
+ vertices[idx * 2] = x;
+ vertices[(idx * 2) + 1] = y;
+ }
+
+ data->glVertexPointer(2, GL_FLOAT, 0, vertices);
if (count > 2 &&
points[0].x == points[count-1].x && points[0].y == points[count-1].y) {
/* GL_LINE_LOOP takes care of the final segment */
@@ -842,6 +866,7 @@ GLES_RenderDrawLines(SDL_Renderer * renderer, const SDL_FPoint * points,
/* We need to close the endpoint of the line */
data->glDrawArrays(GL_POINTS, count-1, 1);
}
+ SDL_stack_free(vertices);
return 0;
}