Add a simple compute shader with in- and output

QTProject/subdivision.compute

-#version 430
+#version 430 core
 
-layout (local_size_x = 1) in;
-void main() {
+layout  (local_size_x  =  2)  in;
+
+layout(std430, binding=0) readonly buffer Input {
+    float offset;
+};
+
+layout(std430, binding=1) writeonly buffer Output {
+    float data[];
+};
+
+void main(){
+    data[gl_GlobalInvocationID.x] = 100 * gl_GlobalInvocationID.x + gl_LocalInvocationID.x + offset;
 }

QTProject/subdivision.cpp

@@ -95,4 +95,52 @@ void Subdivision::precomputeTables(Mesh *mesh) {
 }
 
 void Subdivision::runShader(Mesh *mesh) {
+    /*
+     * This shader will set the output buffer to its global ID times hundred + the local id + offset.
+     *
+     * So, for offset = 0 we will get 0, 101, 200, 301 and so on as there's two threads in a local group.
+     */
+
+    qDebug()<<"Running compute shader";
+    int num = 6 * 2; // must be a multiple of two as we do not handle the other case
+    GLfloat offset = 3.0f;
+
+    shader->bind();
+
+    // Create an input buffer and set it to the value of offset
+    GLuint offsetBufferID;
+    f->glGenBuffers(1, &offsetBufferID);
+    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, offsetBufferID);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(GLfloat), &offset, GL_DYNAMIC_DRAW);
+
+    // Create an output buffer
+    GLuint bufferID;
+    f->glGenBuffers(1, &bufferID);
+    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, bufferID);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(GLfloat) * num, NULL, GL_DYNAMIC_DRAW);
+
+    // Run the shader
+    f->glDispatchCompute(num/2, 1, 1);
+
+    // Wait for the shader to complete and the data to be written back to the global memory
+    f->glMemoryBarrier(GL_SHADER_STORAGE_BARRIER_BIT);
+
+    // Unbind the buffers from the shader
+    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, 0);
+    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, 0);
+
+    // Map the output buffer so we can read the results
+    f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, bufferID);
+    GLfloat *ptr;
+    ptr = (GLfloat *) f->glMapBuffer(GL_SHADER_STORAGE_BUFFER, GL_WRITE_ONLY);
+    for (int i = 0; i < num; i++) {
+        qDebug()<<i<<ptr[i];
+    }
+    f->glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
+
+    // Delete the buffers the free the resources
+    f->glDeleteBuffers(1, &offsetBufferID);
+    f->glDeleteBuffers(1, &bufferID);
+
+    shader->release();
 }