How do you get the size of an image unit (eg. image2D) in GLSL just like textureSize

Question

textureSize is a handy function to get texture dimensions in a shader without having to pass them in by hand as uniforms.

Is there a similar API for image units?

Answer 1

Yes, it's in OpenGL 4.3:

• imageSize() docs
• imageSize() wiki
• ARB_shader_image_size specs

Example:

layout(rgba32f) uniform image2D myImage;
...
ivec2 size = imageSize(myImage);