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Fixed bug 3350 - GL renderers don't need to flip rows after reading back pixels from the target texture 

Simon Hug

All OpenGL renderers always flip the rows of the pixels that come from glReadPixels. This is unnecessary for target textures since these are already top down.

Also, the rect->y value can be used directly for target textures for the same reason. I don't see any code that would handle the logical render size for target textures. Or am I missing something?

The attached patch makes the renderers only the flip rows if the data comes from the default framebuffer.
This commit is contained in:
Sam Lantinga 2016-10-01 11:34:04 -07:00
parent 9fff05f8d6
commit 51d6371ec1
3 changed files with 51 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
src/render/opengl/SDL_render_gl.c
View File

@ -1439,28 +1439,30 @@ GL_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
data->glPixelStorei(GL_PACK_ROW_LENGTH, data->glPixelStorei(GL_PACK_ROW_LENGTH,
(temp_pitch / SDL_BYTESPERPIXEL(temp_format))); (temp_pitch / SDL_BYTESPERPIXEL(temp_format)));
data->glReadPixels(rect->x, (h-rect->y)-rect->h, rect->w, rect->h, data->glReadPixels(rect->x, renderer->target ? rect->y : (h-rect->y)-rect->h,
format, type, temp_pixels); rect->w, rect->h, format, type, temp_pixels);
if (GL_CheckError("glReadPixels()", renderer) < 0) { if (GL_CheckError("glReadPixels()", renderer) < 0) {
SDL_free(temp_pixels); SDL_free(temp_pixels);
return -1; return -1;
} }
/* Flip the rows to be top-down */ /* Flip the rows to be top-down if necessary */
length = rect->w * SDL_BYTESPERPIXEL(temp_format); if (!renderer->target) {
src = (Uint8*)temp_pixels + (rect->h-1)*temp_pitch; length = rect->w * SDL_BYTESPERPIXEL(temp_format);
dst = (Uint8*)temp_pixels; src = (Uint8*)temp_pixels + (rect->h-1)*temp_pitch;
tmp = SDL_stack_alloc(Uint8, length); dst = (Uint8*)temp_pixels;
rows = rect->h / 2; tmp = SDL_stack_alloc(Uint8, length);
while (rows--) { rows = rect->h / 2;
SDL_memcpy(tmp, dst, length); while (rows--) {
SDL_memcpy(dst, src, length); SDL_memcpy(tmp, dst, length);
SDL_memcpy(src, tmp, length); SDL_memcpy(dst, src, length);
dst += temp_pitch; SDL_memcpy(src, tmp, length);
src -= temp_pitch; dst += temp_pitch;
src -= temp_pitch;
}
SDL_stack_free(tmp);
} }
SDL_stack_free(tmp);
status = SDL_ConvertPixels(rect->w, rect->h, status = SDL_ConvertPixels(rect->w, rect->h,
temp_format, temp_pixels, temp_pitch, temp_format, temp_pixels, temp_pitch,

32
src/render/opengles/SDL_render_gles.c
View File

@ -1088,23 +1088,25 @@ GLES_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
data->glPixelStorei(GL_PACK_ALIGNMENT, 1); data->glPixelStorei(GL_PACK_ALIGNMENT, 1);
data->glReadPixels(rect->x, (h-rect->y)-rect->h, rect->w, rect->h, data->glReadPixels(rect->x, renderer->target ? rect->y : (h-rect->y)-rect->h,
GL_RGBA, GL_UNSIGNED_BYTE, temp_pixels); rect->w, rect->h, GL_RGBA, GL_UNSIGNED_BYTE, temp_pixels);
/* Flip the rows to be top-down */ /* Flip the rows to be top-down if necessary */
length = rect->w * SDL_BYTESPERPIXEL(temp_format); if (!renderer->target) {
src = (Uint8*)temp_pixels + (rect->h-1)*temp_pitch; length = rect->w * SDL_BYTESPERPIXEL(temp_format);
dst = (Uint8*)temp_pixels; src = (Uint8*)temp_pixels + (rect->h-1)*temp_pitch;
tmp = SDL_stack_alloc(Uint8, length); dst = (Uint8*)temp_pixels;
rows = rect->h / 2; tmp = SDL_stack_alloc(Uint8, length);
while (rows--) { rows = rect->h / 2;
SDL_memcpy(tmp, dst, length); while (rows--) {
SDL_memcpy(dst, src, length); SDL_memcpy(tmp, dst, length);
SDL_memcpy(src, tmp, length); SDL_memcpy(dst, src, length);
dst += temp_pitch; SDL_memcpy(src, tmp, length);
src -= temp_pitch; dst += temp_pitch;
src -= temp_pitch;
}
SDL_stack_free(tmp);
} }
SDL_stack_free(tmp);
status = SDL_ConvertPixels(rect->w, rect->h, status = SDL_ConvertPixels(rect->w, rect->h,
temp_format, temp_pixels, temp_pitch, temp_format, temp_pixels, temp_pitch,

32
src/render/opengles2/SDL_render_gles2.c
View File

@ -1834,26 +1834,28 @@ GLES2_RenderReadPixels(SDL_Renderer * renderer, const SDL_Rect * rect,
SDL_GetRendererOutputSize(renderer, &w, &h); SDL_GetRendererOutputSize(renderer, &w, &h);
data->glReadPixels(rect->x, (h-rect->y)-rect->h, rect->w, rect->h, data->glReadPixels(rect->x, renderer->target ? rect->y : (h-rect->y)-rect->h,
GL_RGBA, GL_UNSIGNED_BYTE, temp_pixels); rect->w, rect->h, GL_RGBA, GL_UNSIGNED_BYTE, temp_pixels);
if (GL_CheckError("glReadPixels()", renderer) < 0) { if (GL_CheckError("glReadPixels()", renderer) < 0) {
return -1; return -1;
} }
/* Flip the rows to be top-down */ /* Flip the rows to be top-down if necessary */
length = rect->w * SDL_BYTESPERPIXEL(temp_format); if (!renderer->target) {
src = (Uint8*)temp_pixels + (rect->h-1)*temp_pitch; length = rect->w * SDL_BYTESPERPIXEL(temp_format);
dst = (Uint8*)temp_pixels; src = (Uint8*)temp_pixels + (rect->h-1)*temp_pitch;
tmp = SDL_stack_alloc(Uint8, length); dst = (Uint8*)temp_pixels;
rows = rect->h / 2; tmp = SDL_stack_alloc(Uint8, length);
while (rows--) { rows = rect->h / 2;
SDL_memcpy(tmp, dst, length); while (rows--) {
SDL_memcpy(dst, src, length); SDL_memcpy(tmp, dst, length);
SDL_memcpy(src, tmp, length); SDL_memcpy(dst, src, length);
dst += temp_pitch; SDL_memcpy(src, tmp, length);
src -= temp_pitch; dst += temp_pitch;
src -= temp_pitch;
}
SDL_stack_free(tmp);
} }
SDL_stack_free(tmp);
status = SDL_ConvertPixels(rect->w, rect->h, status = SDL_ConvertPixels(rect->w, rect->h,
temp_format, temp_pixels, temp_pitch, temp_format, temp_pixels, temp_pitch,