Created attachment 138904 [details] source code of example I found a issue in ANGLE project that draw does not work, and had written a simple example to reproduce this issue, attachment is the source code. Steps: 1. gcc -o srgb srgb.c -lX11 -lepoxy 2. ./srgb I had used readPixels to get fbo content and wrote content to files in current directory, the name is "result_1/2/3/4.rgba", These files were all empty, it seems that mesa did draw nothing. The same case had run on NVIDIA GPU, which draw something normally. I had spent some time to debug it, but did not find the root cause. Please help me to check it, thank you.
Your variant: GLubyte pixels_4[128 * 128 * 4]; glReadPixels(0, 0, 128, 128, GL_RGBA, GL_UNSIGNED_BYTE, &pixels_4[0]); FILE *outputFile_4 = fopen("result_4.rgba", "a"); fprintf(outputFile_4, "%s\n", (char *)(pixels_4)); fclose(outputFile_4); Proposed variant: GLubyte pixels_4[128 * 128 * 4]; glReadPixels(0, 0, 128, 128, GL_RGBA, GL_UNSIGNED_BYTE, &pixels_4[0]); FILE *outputFile_4 = fopen("result_4.rgba", "a"); //fprintf(outputFile_4, "%s\n", (char *)(pixels_4)); fwrite( pixels_4, sizeof pixels_4[0], sizeof(pixels_4)/sizeof(pixels_4[0]), outputFile_4 ); fclose(outputFile_4); In all of these files after changing the code (as I pasted higher) - was written repeated values of 00 00 00 FF. Each file has the same size - 65536 B. In your variant each time should contain only 0A "\n" because first byte of pixels_N contains 00. Are you sure that output for Nvidia had correct (expected) values??
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