* return -1 for an invalid buffer.
*/
static gl_buffer_index
-read_buffer_enum_to_index(GLenum buffer)
+read_buffer_enum_to_index(const struct gl_context *ctx, GLenum buffer)
{
switch (buffer) {
case GL_FRONT:
return BUFFER_FRONT_LEFT;
case GL_BACK:
+ if (_mesa_is_gles(ctx)) {
+ /* In draw_buffer_enum_to_bitmask, when GLES contexts draw to
+ * GL_BACK with a single-buffered configuration, we actually end
+ * up drawing to the sole front buffer in our internal
+ * representation. For consistency, we must read from that
+ * front left buffer too.
+ */
+ if (!ctx->DrawBuffer->Visual.doubleBufferMode)
+ return BUFFER_FRONT_LEFT;
+ }
return BUFFER_BACK_LEFT;
case GL_RIGHT:
return BUFFER_FRONT_RIGHT;
if (_mesa_is_gles3(ctx) && !is_legal_es3_readbuffer_enum(buffer))
srcBuffer = -1;
else
- srcBuffer = read_buffer_enum_to_index(buffer);
+ srcBuffer = read_buffer_enum_to_index(ctx, buffer);
if (srcBuffer == -1) {
_mesa_error(ctx, GL_INVALID_ENUM,