In ES 3.0, when calling glDrawBuffers() on the window system
framebuffer, the only valid targets are GL_NONE or GL_BACK. Since there
is no stereo rendering in ES 3.0, this is a single buffer, unlike
desktop where it may be two (and thus isn't allowed).
For single-buffered configs, GL_BACK ironically means the front (and
only) buffer. I'm not sure that it matters, however, as ES shouldn't
have front buffer rendering in the first place.
Fixes es3conform framebuffer_blit_coverage_default_draw_buffer_binding.
---
src/mesa/main/buffers.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
These two patches are a proposed replacement for Anuj's patch 1/6.
diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c
index aa9b9f0..244f4de 100644
--- a/src/mesa/main/buffers.c
+++ b/src/mesa/main/buffers.c
@@ -94,7 +94,7 @@ supported_buffer_bitmask(const struct gl_context *ctx,
* GL_FRONT_AND_BACK), return the corresponding bitmask of BUFFER_BIT_* flags.
*/
static GLbitfield
-draw_buffer_enum_to_bitmask(GLenum buffer)
+draw_buffer_enum_to_bitmask(const struct gl_context *ctx, GLenum buffer)
{
switch (buffer) {
case GL_NONE:
@@ -102,6 +102,19 @@ draw_buffer_enum_to_bitmask(GLenum buffer)
case GL_FRONT:
return BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_FRONT_RIGHT;
case GL_BACK:
+ if (_mesa_is_gles3(ctx)) {
+ /* From the ES 3.0 specification, page 180:
+ * "When draw buffer zero is BACK, color values are written into
+ * the sole buffer for single-buffered contexts, or into the back
+ * buffer for double-buffered contexts."
+ *
+ * Since there is no stereo rendering in ES 3.0, only return the
+ * LEFT bits. This also satisfies the "n must be 1" requirement.
+ */
+ if (ctx->DrawBuffer->Visual.doubleBufferMode)
+ return BUFFER_BIT_BACK_LEFT;
+ return BUFFER_BIT_FRONT_LEFT;
+ }
return BUFFER_BIT_BACK_LEFT | BUFFER_BIT_BACK_RIGHT;
case GL_RIGHT:
return BUFFER_BIT_FRONT_RIGHT | BUFFER_BIT_BACK_RIGHT;
@@ -241,7 +254,7 @@ _mesa_DrawBuffer(GLenum buffer)
else {
const GLbitfield supportedMask
= supported_buffer_bitmask(ctx, ctx->DrawBuffer);
- destMask = draw_buffer_enum_to_bitmask(buffer);
+ destMask = draw_buffer_enum_to_bitmask(ctx, buffer);
if (destMask == BAD_MASK) {
/* totally bogus buffer */
_mesa_error(ctx, GL_INVALID_ENUM,
@@ -321,7 +334,7 @@ _mesa_DrawBuffers(GLsizei n, const GLenum *buffers)
return;
}
- destMask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
+ destMask[output] = draw_buffer_enum_to_bitmask(ctx, buffers[output]);
/* From the OpenGL 3.0 specification, page 258:
* "Each buffer listed in bufs must be one of the values from tables
@@ -451,7 +464,7 @@ _mesa_drawbuffers(struct gl_context *ctx, GLuint n, const
GLenum *buffers,
const GLbitfield supportedMask = supported_buffer_bitmask(ctx, fb);
GLuint output;
for (output = 0; output < n; output++) {
- mask[output] = draw_buffer_enum_to_bitmask(buffers[output]);
+ mask[output] = draw_buffer_enum_to_bitmask(ctx, buffers[output]);
ASSERT(mask[output] != BAD_MASK);
mask[output] &= supportedMask;
}
--
1.8.0.2
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