Simon Hug
The bug is in the GL_ResetState and GLES_ResetState functions which get called after a new GL context is created. These functions set the cached current color to transparent black, but the GL specification says the initial color is opaque white.
The attached patch changes the values to 0xffffffff to reflect the initial state of the current color. Should the ResetState functions get called anywhere else in the future, this probably has to call the GL functions itself to ensure that the colors match.
Tom Seddon
GL_ActivateRenderer may call GL_UpdateViewport, which leaves the GL_PROJECTION matrix selected. But after GL_ResetState, the GL_MODELVIEW matrix is selected, suggesting that's the intended default state.
It seems at least like these should be consistent. Presumably GL_UpdateViewport should be doing a glMatrixMode(GL_MODELVIEW) before it finishes.
Richard Russell
Resuming from a suspended state results in a black screen. This only happens when using GLES 1.1 (GLES 2 resumes correctly) and when the render target has been changed using SDL_SetRenderTarget. This problem is new in 2.0.4.
The attached test case demonstrates the issue.
Sylvain Becker has apparently found a fix as follows:
"In the opengles leaf function (in 'src/render/opengles/SDL_render_gles.c'), it appears there is a call to 'GLES_ActivateRenderer' in 'GLES_SetRenderTarget', which is not present in opengles2. When commenting out this 'GLES_ActivateRenderer', it seems to resume fine".
This appears to fix the testcase perfectly, but I don't know whether it could have any undesirable side-effects.
Call SDL_GL_GetDrawableSize() directly because we may be in the initialization path and SDL_GetRendererOutputSize() will fail because the renderer magic isn't set up yet.
ny00
Using the OpenGL ES 1.1 renderer, after updating a texture with SDL_UpdateTexture (or SDL_UnlockTexture), a following call to SDL_RenderFillRect draws a rectangle with the wrong color (which appears to be the same as the texture's top-left pixel).
Comparing SDL_render_gles.c:GLES_UpdateTexture to SDL_render_gl.c:GL_UpdateTexture, a missing call to glDisable appears to be the cause. After adding it back, the bug is resolved.
Simon Hug
The description of the SDL_RenderClear function in the SDL_render.h header says the following:
"This function clears the entire rendering target, ignoring the viewport."
The word "entire" implies that the clipping rectangle set with SDL_RenderSetClipRect also gets ignored. This is left somewhat ambiguous if only the viewport is mentioned. Minor thing, but let's see what the implementations actually do.
The software renderer ignores the clipping rectangle when clearing. It even has a comment on this: /* By definition the clear ignores the clip rect */
Most other render drivers (opengl, opengles, opengles2, direct3d, and psp [I assume. Can't test it.]) use the scissor test for the ClipRect and don't disable it when clearing. Clearing will only happen within the clipping rectangle for these drivers.
An exception is direct3d11 which uses a clear function that ignores the scissor test.
Simon Hug
When updating the viewport in GLES_UpdateViewport, the OpenGL ES renderer doesn't flip the projection matrix for target textures. The lines, rectangles and textures (if drawn with glDrawArrays) are upside down when drawing to target textures.
Simon Hug
The OpenGL ES 2 renderer does not check the target texture format when using SDL_RenderReadPixels and just always uses ABGR8888. This can result in swapped or wrong colors.
The attached patch adds a check and selects the target texture format, if a texture is set as the target.
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.
Simon Hug
The GL_SetBlendMode and GLES_SetBlendMode functions of the opengl and opengles renderers call the glTexEnvf to set the texture env mode to either GL_MODULATE (the default) or GL_REPLACE for the NONE blend mode. Using GL_REPLACE disables color and alpha modulation for textures.
These glTexEnv calls were put in the SetBlendMode function back in 2006 [1], but there the NONE code still used the GL_DECAL mode. The GL_REPLACE mode came in 2008 [2]. I'm a bit confused why that wasn't always GL_MODULATE and a bit surprised nobody reported that yet (unless I missed it). I guess only a few use the gles renderer and the newish shaders mask the issue.
Simon Hug
It seems not everyone implemented glDrawTexfOES the same. Intel and Mesa ignore the viewport entirely, whereas the Raspberry Pi implementation offsets the coordinates and does viewport clipping.
The glDrawTexfOES extension text [1] for the function says "Xs and Ys are given directly in window (viewport) coordinates." I guess this wasn't clear enough.
Alex Szpakowski
Honestly I'd probably remove that codepath from SDL_Render entirely. It's an OpenGL ES 1-specific extension that isn't likely to give huge performance gains and adds additional maintenance overhead to SDL_Render while also having bugs in some drivers (as seen here).
The internal function SDL_EGL_LoadLibrary() did not delete and remove a mostly
uninitialized data structure if loading the library first failed. A later try to
use EGL then skipped initialization and assumed it was previously successful
because the data structure now already existed. This led to at least one crash
in the internal function SDL_EGL_ChooseConfig() because a NULL pointer was
dereferenced to make a call to eglBindAPI().
Sam Lantinga
Philipp Wiesemann
Ryan C. Gordon
Alex Szpakowski