RHI: Add Compute Pipeline abstraction with D3D12 and OpenGL support

- Add SetComputeShader/GetComputeShader/HasComputeShader to RHIPipelineState
- Add m_computePipelineState for D3D12 compute PSO
- Add m_computeProgram/m_computeShader for OpenGL
- Fix OpenGLCommandList::DispatchCompute bug (was ignoring x,y,z params)
- Fix OpenGLShader::GetID usage in OpenGLPipelineState
- Mark Priority 8 as completed in RHI_Design_Issues.md

engine/src/RHI/OpenGL/OpenGLPipelineState.cpp

@@ -1,4 +1,5 @@
 #include "XCEngine/RHI/OpenGL/OpenGLPipelineState.h"
+#include "XCEngine/RHI/OpenGL/OpenGLShader.h"
 #include <glad/glad.h>
 
 namespace XCEngine {
@@ -37,6 +38,16 @@ void OpenGLPipelineState::SetRenderTargetFormats(uint32_t count, const uint32_t*
 void OpenGLPipelineState::SetSampleCount(uint32_t count) {
 }
 
+void OpenGLPipelineState::SetComputeShader(RHIShader* shader) {
+    m_computeShader = shader;
+    if (shader) {
+        OpenGLShader* glShader = static_cast<OpenGLShader*>(shader);
+        m_computeProgram = glShader->GetID();
+    } else {
+        m_computeProgram = 0;
+    }
+}
+
 PipelineStateHash OpenGLPipelineState::GetHash() const {
     PipelineStateHash hash = {};
     return hash;
@@ -44,11 +55,15 @@ PipelineStateHash OpenGLPipelineState::GetHash() const {
 
 void OpenGLPipelineState::Shutdown() {
     m_program = 0;
+    m_computeProgram = 0;
+    m_computeShader = nullptr;
     m_programAttached = false;
 }
 
 void OpenGLPipelineState::Bind() {
-    if (m_programAttached) {
+    if (HasComputeShader()) {
+        glUseProgram(m_computeProgram);
+    } else if (m_programAttached) {
         glUseProgram(m_program);
     }
     Apply();