ADD: IBL added

shaders/background_env.frag

@@ -0,0 +1,31 @@
+#version 450
+#extension GL_GOOGLE_include_directive : require
+#include "input_structures.glsl"
+
+layout(location=0) in vec2 inUV;
+layout(location=0) out vec4 outColor;
+
+// IBL specular equirect 2D (LOD 0 for background)
+layout(set=3, binding=0) uniform sampler2D iblSpec2D;
+
+vec2 dir_to_equirect(vec3 d)
+{
+    d = normalize(d);
+    float phi = atan(d.z, d.x);
+    float theta = acos(clamp(d.y, -1.0, 1.0));
+    return vec2(phi * (0.15915494309) + 0.5, theta * (0.31830988618));
+}
+
+void main()
+{
+    // Reconstruct world-space direction from screen UV
+    vec2 ndc = inUV * 2.0 - 1.0; // [-1,1]
+    vec4 clip = vec4(ndc, 1.0, 1.0);
+    vec4 vpos = inverse(sceneData.proj) * clip;
+    vec3 viewDir = normalize(vpos.xyz / max(vpos.w, 1e-6));
+    vec3 worldDir = normalize((inverse(sceneData.view) * vec4(viewDir, 0.0)).xyz);
+
+    vec2 uv = dir_to_equirect(worldDir);
+    vec3 col = textureLod(iblSpec2D, uv, 0.0).rgb;
+    outColor = vec4(col, 1.0);
+}