GLSL's imageLoad() always returns 0?

Question

I have created a texture and filled it with some data:

glBindTexture(GL_TEXTURE_2D, head_pointer_image);
glTexImage2D(GL_TEXTURE_2D, 0, GL_R32UI, width, height, 0, GL_RED_INTEGER, GL_UNSIGNED_INT, data);

Then I bound it to 0:

glBindImageTexture(0, head_pointer_image, 0, GL_FALSE, 0, GL_READ_WRITE, GL_R32UI); 
glUniform1ui(0, 0); // Not sure if necessary

If I check the data with glGetTexImage() I get correct values, but if I try to read it in my shader, I only get zeros.

layout(binding = 0, r32ui) coherent uniform uimage2D head_pointer_image;

uint value = imageLoad(head_pointer_image, ivec2(gl_FragCoord.xy)).r;

What am I doing wrong?

Instead of `ivec2(gl_FragCoord.xy)` try with hard-coded values, so as to discard other causes. — Ripi2, Sep 18 '18 at 16:38
I think change to readonly in shader will need change in call to glBindImageTexture(0, head_pointer_image, 0, GL_FALSE, 0, GL_READ_ONLY, GL_R32UI); — Paritosh Kulkarni, Sep 18 '18 at 16:43
@Ripi2 I tried, but still nothing. Have also changed to GL_READ_ONLY. I am not getting any errors with glGetError() either. — Rhu Mage, Sep 18 '18 at 16:59
@Ripi2 You mean glTexStorage2D instead of glTexImage2D? I can't use both right? Replacing it didn't change anything. Tried the other suggestions too and still only zeros. — Rhu Mage, Sep 18 '18 at 18:06
@RhuMage Yes, you can define the storage **and** later change (by glTexImage..) the data. I've run out of ideas. Perhaps seeing the full code reveals hidden cause... — Ripi2, Sep 18 '18 at 18:11
@Ripi2 Here's my code: https://github.com/Rhumage/imageLoad/blob/master/opengltest/Engine.cpp https://github.com/Rhumage/imageLoad/blob/master/opengltest/shaders/second.fs — Rhu Mage, Sep 18 '18 at 19:34

score 0 · Accepted Answer · answered Sep 21 '18 at 07:51

I have received outside help, the problem was that my texture was incomplete due to the default minification filtering being GL_NEAREST_MIPMAP_LINEAR which requires a full mipmap chain and I only had the base level image.

Setting GL_TEXTURE_MIN_FILTER to GL_LINEAR fixed my issue.

GLSL's imageLoad() always returns 0?

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