Weird ImageStore Behaviour

OpenGL
1

I found that my fragment or compute shader cannot imageStore anything to the multi-channel image texture initialized in this way.

Method A:

	
        glGenTextures(1, &tex);
	glBindTexture(GL_TEXTURE_2D, tex);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, imgWidth, imgHeight, 0, GL_RGBA, GL_FLOAT, NULL);

I got an all zero buffer when I read back using glGetTextureImage.

However, when I changed the initialization to this:

Method B:

	
        glGenTextures(1, &tex);
	glBindTexture(GL_TEXTURE_2D, tex);
	glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA32F, imgWidth, imgHeight);

The problem was fixed.

(For both, I bind the texture to the image unit by

	
	glBindImageTexture(1, tex, 0, GL_FALSE, 0, GL_READ_WRITE, GL_RGBA32F);

)

The weird thing is that method A works when I use single channel texture (e.g. GL32F).

Is that incorrect use of API or is it the driver’s problem?

Thanks.

2

Are you using glMemoryBarrier?

3

I added glMemoryBarrier(GL_ALL_BARRIER_BITS) between the draw call and the glGetTextureImage call, but still got a zero image when using initialization method A.

4

It looks like it might be a driver bug. Which GPU and driver are you using?

If you post a short, standalone test program, folks here could try your code and give you testing results, as well as help check that you’re not missing something important.

5

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