feat: add spot light shadows with a tilled buffer

destrum/assets_src/shaders/mesh.frag

@@ -34,6 +34,32 @@ vec3 calculateNormal(MaterialData material, uint samplerID)
     return normalize(mat3(t, b, n) * tangentNormal);
 }
 
+float calculateShadow(Light light, vec3 fragPos, vec3 geometryNormal)
+{
+    if (light.shadowIndex == NO_SHADOW) {
+        return 1.0;
+    }
+
+    if (light.type == TYPE_DIRECTIONAL_LIGHT) {
+        return calculateDirectionalShadow(
+            fragPos, geometryNormal,
+            pcs.sceneData.lightViewProj,
+            pcs.sceneData.shadowMapId,
+            pcs.sceneData.shadowNormalOffset);
+    }
+
+    if (light.type == TYPE_SPOT_LIGHT) {
+        return calculateSpotShadow(
+            fragPos, geometryNormal, light.position,
+            pcs.sceneData.spotShadows[light.shadowIndex],
+            light.shadowIndex,
+            pcs.sceneData.spotShadowAtlasId,
+            pcs.sceneData.spotShadowTilesPerRow);
+    }
+
+    return 1.0;
+}
+
 void main()
 {
     MaterialData material = pcs.sceneData.materials.data[pcs.materialID];
@@ -73,19 +99,13 @@ void main()
     uint tileOffset = (tileID.y * pcs.sceneData.tileCountX + tileID.x) * LIGHT_TILE_STRIDE;
     uint tileLightCount = pcs.sceneData.tileLightIndices.data[tileOffset];
 
+    vec3 geometryNormal = normalize(inNormal);
     vec3 fragColor = vec3(0.0);
     for (uint i = 0; i < tileLightCount; i++) {
         uint lightIndex = pcs.sceneData.tileLightIndices.data[tileOffset + 1 + i];
         Light light = pcs.sceneData.lights.data[lightIndex];
 
-        float shadow = 1.0;
-        if (light.castShadows != 0) {
-            shadow = calculateDirectionalShadow(
-                fragPos, normalize(inNormal),
-                pcs.sceneData.lightViewProj,
-                pcs.sceneData.shadowMapId,
-                pcs.sceneData.shadowNormalOffset);
-        }
+        float shadow = calculateShadow(light, fragPos, geometryNormal);
 
         fragColor += calculateLight(light, fragPos, n, v,
             diffuseColor, roughness, metallic, f0, shadow);