I am using OpenGL 4.3 core profile to do various things in OpenGL under Linux. I am having trouble when using shader storage buffers where the last component of a shader storage block is an unsized array. I do not have this problem when using the NVIDIA driver. Is this a driver bug, or am I doing something wrong??
Description of problem:
It appears that the ".length()" function for unsized arrays at the end of shader storage blocks always returns 0. This is contrary to the specification for GL_ARB_shader_storage_buffer_object where "Issue (19)" describes ".length()" as returning the size of unsized arrays based on the size of the provided buffer object.
Steps to reproduce:
1. Include a shader with a shader storage block containing an unsized array as the last component
...
layout(std430, binding=0) buffer Test
{
float test[];
}
...
2. Bind a shader storage buffer with a size equivalent to the desired shader storage block unsized array size in bytes
...
GLuint testBuffer;
glGenBuffers(1, &testBuffer);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, testBuffer);
glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(float)*4, NULL, GL_DYNAMIC_DRAW);
...
3. In the shader, access the shader storage block unsized array ".length()" function and check that it contains the number of elements we allocated via
glBufferData.
...
int elements = test.length();
if(elements!=4)
{
// the .length() function has returned a value outside the
// GL_ARB_shader_storage_buffer_object specification
}
...
Actual result:
elements = 0
Expected result:
elements = 4
