How to bind shader buffer blocks using glShaderStorageBinding?

Question

Using OpenGL 4.3, I want to know how to bind shader buffer blocks using glShaderStorageBinding.

'binding' qualifiers works fine, but I don't want to use them.

I have written the following code:

    GLint i=0, j=0, Ibuffer[32], *Obuffer;
    GLuint shader_buffer[2], buffer_index;

   for(i=0; i<32; i++)  
   {
       Ibuffer[i]=1;

   }

    Obuffer=(GLint*) malloc(32*sizeof(GLint));

glGenBuffers(2, shader_buffer, nResult);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, shader_buffer[0]);
glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(Ibuffer), Ibuffer, GL_DYNAMIC_DRAW);

glBindBuffer(GL_SHADER_STORAGE_BUFFER, shader_buffer[1], nResult);
glBufferData( GL_SHADER_STORAGE_BUFFER, 32*sizeof(GLint), NULL, GL_DYNAMIC_READ);
GLint x;
glGetIntegerv(GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS, &x);
glUseProgram(computeshaderprogObj);
buffer_index=glGetProgramResourceIndex(computeshaderprogObj, GL_SHADER_STORAGE_BLOCK, "iB");
printf("buffer_index = %d GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS = %d", buffer_index, x);
glShaderStorageBlockBinding(computeshaderprogObj, buffer_index, 0);

buffer_index=glGetProgramResourceIndex(computeshaderprogObj, GL_SHADER_STORAGE_BLOCK, "oB");
printf("buffer_index = %d", buffer_index);
glShaderStorageBlockBinding(computeshaderprogObj, buffer_index, 1);

glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, shader_buffer[0]);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, shader_buffer[1]);

 glDispatchCompute(4, 1, 1);
 glBindBuffer(GL_SHADER_STORAGE_BUFFER, shader_buffer[1]);
 Obuffer = (GLint*)glMapBufferRange(GL_SHADER_STORAGE_BUFFER, 0, sizeof(GLint)*32, GL_MAP_READ_BIT); 
 // Reading the buffer
 glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);

Compute Shader:

layout (local_size_x = 32, local_size_y = 1, local_size_z = 1) in;
layout(std140) buffer iB {
   int ibuf[];
}g_in;

layout(std140) buffer oB {
  int obuf[];
}g_out;
void main() {
uint LocalInvocationIndex = gl_LocalInvocationIndex;
g_out.obuf[LocalInvocationIndex] = g_in.ibuf[LocalInvocationIndex];
  }

Expecting result as 1, but returning value as 0 in Obuffer.

output:
buffer_index = 0 GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS = 96
buffer_index = 1
value at Obuffer[1]=0

You have a couple of lines of `printf (...)` in your code. Would you mind including their output in your question? — Andon M. Coleman, Oct 01 '13 at 06:52

score 1 · Answer 1 · answered Oct 03 '13 at 11:28

1

I found the answer, it was giving wrong because of the 'std140' layout. It was saving result as 1000, 1000, 1000, etc.. Thus changed the layout qualifier as packed. Thanks.

answered Oct 03 '13 at 11:28

user1896853

107
1
9

How to bind shader buffer blocks using glShaderStorageBinding?

Compute Shader:

1 Answers1