wip

src/normals.frag.glsl

@@ -5,6 +5,8 @@
 #include "include.glsl"
 #include "implicit_include.glsl"
 
+#define tau 6.28318530717958647692
+
 layout(location = 0) in vec2 v_pos;
 
 layout(input_attachment_index = 0, set = 2, binding = 0) uniform usubpassInput u_material;
@@ -50,18 +52,60 @@ vec3 getBiTangent(vec3 n, vec3 t) {
     return normalize(cross(n, t));
 }
 
-const float AO_INSTENSITY = 0.1;
-const float AO_STEP = 0.01;
+uvec4 hash;
+
+uvec4 pcg4d(uvec4 v) {
+    v = v * 1664525u + 1013904223u;
+    v.x += v.y * v.w;
+    v.y += v.z * v.x;
+    v.z += v.x * v.y;
+    v.w += v.y * v.z;
+    v ^= v >> 16u;
+    v.x += v.y * v.w;
+    v.y += v.z * v.x;
+    v.z += v.x * v.y;
+    v.w += v.y * v.z;
+    return v;
+}
+
+// Construct a float with half-open range [0:1] using low 23 bits.
+// All zeroes yields 0.0, all ones yields the next smallest representable value below 1.0.
+float floatConstruct(uint m) {
+    const uint ieeeMantissa = 0x007FFFFFu; // binary32 mantissa bitmask
+    const uint ieeeOne = 0x3F800000u; // 1.0 in IEEE binary32
+
+    m &= ieeeMantissa; // Keep only mantissa bits (fractional part)
+    m |= ieeeOne; // Add fractional part to 1.0
+
+    float f = uintBitsToFloat(m); // Range [1:2]
+    return f - 1.0; // Range [0:1]
+}
+
+vec3 getPointOnSphere(vec2 rv) {
+    float a = tau * rv.x;
+    float b = 2.0 * rv.y - 1.0;
+    float c = sqrt(1.0 - b * b);
+    vec3 h = vec3(c * cos(a), b, c * sin(a));
+    return h;
+}
+
+const float AO_INTENSITY = 0.1;
+const float AO_STEP = 0.02;
 const uint AO_MAX_ITER = 10;
 
 float getOcclusion(vec3 p, vec3 n) {
     float ao = 0.0;
-    float dist;
-    for (uint i = 1; i < AO_MAX_ITER; i++) {
-        dist = AO_STEP * i;
-        ao += max((dist - scene(vec4(p + n * dist, camera_uniforms.campos_and_time.w))) / dist, 0.0);
-    }
-    return 1.0 - ao * AO_INSTENSITY;
+    //for (uint i = 1; i < AO_MAX_ITER; i++) {
+    //    hash = pcg4d(hash);
+    //    vec3 point = getPointOnSphere(vec2(floatConstruct(hash.x), floatConstruct(hash.y))) * AO_STEP;
+    //    float dist = dot(point, n);
+    //    if (dist < 0) {
+    //        dist = abs(dist);
+    //        point += n * dist * 2.0;
+    //    }
+    //    ao += max((dist - scene(vec4(p + point, camera_uniforms.campos_and_time.w))) / dist, 0.0);
+    //}
+    return 1.0 - ao * AO_INTENSITY;
 }
 
 //Implicit Surface Entrypoint
@@ -70,6 +114,8 @@ void main() {
         discard;
     }
 
+    //hash = uvec4(v_pos.x * 374799253, v_pos.y * 615653626, camera_uniforms.campos_and_time.w * 626228781, 713668633);
+
     float depth = subpassLoad(u_depth).x;
     if (depth == 1.0) {
         discard;