feat: add click to select

destrum/assets_src/shaders/instance_data.glsl

@@ -11,7 +11,7 @@ struct InstanceData {
     mat4 transform;
     VertexBuffer vertexBuffer;
     uint materialID;
-    uint padding;
+    uint objectID;
 };
 
 layout (buffer_reference, scalar) readonly buffer InstanceBuffer {

destrum/assets_src/shaders/mesh.frag

@@ -13,9 +13,23 @@ layout (location = 1) in vec2 inUV;
 layout (location = 2) in vec3 inNormal;
 layout (location = 3) in vec4 inTangent;
 layout (location = 4) flat in uint inMaterialID;
+layout (location = 5) flat in uint inObjectID;
 
 layout (location = 0) out vec4 outFragColor;
 
+// Stable per object, the same object keeps its color between frames and runs
+vec3 selectionColor(uint objectID)
+{
+    if (objectID == 0u) {
+        return vec3(0.0);
+    }
+    uint hash = objectID * 2654435761u;
+    hash ^= hash >> 15;
+    hash *= 2246822519u;
+    hash ^= hash >> 13;
+    return vec3(hash & 255u, (hash >> 8) & 255u, (hash >> 16) & 255u) / 255.0;
+}
+
 vec3 calculateNormal(MaterialData material, uint samplerID)
 {
     vec3 n = normalize(inNormal);
@@ -127,6 +141,10 @@ void main()
         fragColor = mix(fragColor, lightHeatmapColor(tileLightCount), 0.5);
     }
 
+    if (pcs.sceneData.debugSelectionView != 0) {
+        fragColor = selectionColor(inObjectID);
+    }
+
     #if 0
     // TANGENT DEBUG
     if (inTangent == vec4(0.0)) {

destrum/assets_src/shaders/mesh.vert

@@ -9,6 +9,7 @@ layout (location = 1) out vec2 outUV;
 layout (location = 2) out vec3 outNormal;
 layout (location = 3) out vec4 outTangent;
 layout (location = 4) flat out uint outMaterialID;
+layout (location = 5) flat out uint outObjectID;
 
 // The depth pre-pass reuses this shader, positions have to match bit for bit
 // so the main pass can depth test against it with LESS_OR_EQUAL
@@ -34,4 +35,5 @@ void main()
     // w is the bitangent sign, the fragment shader builds the TBN from the interpolated vectors
     outTangent = vec4(mat3(instance.transform) * v.tangent.xyz, v.tangent.w);
     outMaterialID = instance.materialID;
+    outObjectID = instance.objectID;
 }

destrum/assets_src/shaders/scene_data.glsl

@@ -37,7 +37,7 @@ layout (buffer_reference, scalar) readonly buffer SceneDataBuffer {
     // directional shadows
     uint shadowMapId;
     float shadowNormalOffset;
-    uint padding;
+    uint debugSelectionView;
     mat4 lightViewProj;
 
     // spot shadows

destrum/assets_src/shaders/selection.frag

@@ -0,0 +1,16 @@
+#version 460
+
+// Same interface as mesh.vert, only the object ID is used
+layout (location = 0) in vec3 inPos;
+layout (location = 1) in vec2 inUV;
+layout (location = 2) in vec3 inNormal;
+layout (location = 3) in vec4 inTangent;
+layout (location = 4) flat in uint inMaterialID;
+layout (location = 5) flat in uint inObjectID;
+
+layout (location = 0) out uint outObjectID;
+
+void main()
+{
+    outObjectID = inObjectID;
+}