Resolve "Mesh Shader Implementation"

Closes #87 (closed)

projects/mesh_shader/resources/shaders/shader.task

+#version 460
+#extension GL_ARB_separate_shader_objects   : enable
+#extension GL_NV_mesh_shader                : require
+#extension GL_GOOGLE_include_directive      : enable
+
+#include "meshlet.inc"
+#include "common.inc"
+
+layout(local_size_x=32) in;
+
+taskNV out Task {
+  uint meshletIndices[32];
+  mat4 mvp;
+} OUT;
+
+layout( push_constant ) uniform constants{
+    uint matrixIndex;
+    uint meshletCount;
+};
+
+// TODO: reuse mesh stage binding at location 2 after required fix in framework
+layout(std430, binding = 5) readonly buffer meshletBuffer
+{
+    Meshlet meshlets[];
+};
+
+struct Plane{
+    vec3    pointOnPlane;
+    float   padding0;
+    vec3    normal;
+    float   padding1;
+};
+
+layout(set=0, binding=3, std140) uniform cameraPlaneBuffer{
+    Plane cameraPlanes[6];
+};
+
+layout(std430, binding = 4) readonly buffer matrixBuffer
+{
+    ObjectMatrices objectMatrices[];
+};
+
+shared uint taskCount;
+
+bool isSphereInsideFrustum(vec3 spherePos, float sphereRadius, Plane cameraPlanes[6]){
+    bool isInside = true;
+    for(int i = 0; i < 6; i++){
+        Plane p     = cameraPlanes[i];
+        isInside    = isInside && dot(p.normal, spherePos - p.pointOnPlane) - sphereRadius < 0;
+    }
+    return isInside;
+}
+
+void main() {
+
+    if(gl_LocalInvocationID.x >= meshletCount){
+        return;
+    }
+    
+    uint meshletIndex   = gl_GlobalInvocationID.x;
+    Meshlet meshlet     = meshlets[meshletIndex]; 
+    
+    if(gl_LocalInvocationID.x == 0){
+        taskCount = 0;
+    }
+    
+    // TODO: scaling support
+    vec3 meshletPositionWorld = (vec4(meshlet.meanPosition, 1) * objectMatrices[matrixIndex].model).xyz;
+    if(isSphereInsideFrustum(meshletPositionWorld, meshlet.boundingSphereRadius, cameraPlanes)){
+        uint outIndex = atomicAdd(taskCount, 1);
+        OUT.meshletIndices[outIndex] = gl_GlobalInvocationID.x;
+    }
+
+    if(gl_LocalInvocationID.x == 0){
+        gl_TaskCountNV              = taskCount;
+        OUT.mvp = objectMatrices[matrixIndex].mvp;
+    }
+}
\ No newline at end of file