Change project structure;

Added new c# binding;

native/source/Algorithm/MicrofacetGGX.c

@@ -0,0 +1,89 @@
+#include "Algorithm/MicrofacetGGX.h"
+
+// Trowbridge-Reitz GGX Normal Distribution Function
+float ggx_distribution(float n_dot_h, float roughness)
+{
+    float a = roughness * roughness;
+    float a2 = a * a;
+    float n_dot_h2 = n_dot_h * n_dot_h;
+
+    float nom = a2;
+    float denom = (n_dot_h2 * (a2 - 1.0f) + 1.0f);
+    denom = PI * denom * denom;
+
+    return nom / fmaxf(denom, 1e-20f);
+}
+
+float ggx_g1(float n_dot_v, float roughness)
+{
+    if (n_dot_v <= 0.0f)
+    {
+        return 0.0f;
+    }
+
+    // Our GGX D() uses alpha = roughness^2, so keep the same convention here.
+    float alpha = roughness * roughness;
+    float alpha2 = alpha * alpha;
+
+    float n2 = n_dot_v * n_dot_v;
+    float denom = n_dot_v + sqrtf(alpha2 + (1.0f - alpha2) * n2);
+    return (2.0f * n_dot_v) / fmaxf(denom, FLT_EPSILON);
+}
+
+float ggx_g_smith(float n_dot_v, float n_dot_l, float roughness)
+{
+    return ggx_g1(n_dot_v, roughness) * ggx_g1(n_dot_l, roughness);
+}
+
+vec3s ggx_sample_vndf(vec3s n, vec3s v, float roughness, float u1, float u2)
+{
+    // Build local frame around n.
+    vec3s tangent, bitangent;
+    create_orthonormal_basis(n, &tangent, &bitangent);
+
+    // View direction in local coordinates.
+    vec3s v_local = (vec3s){glms_vec3_dot(v, tangent), glms_vec3_dot(v, bitangent), glms_vec3_dot(v, n)};
+    v_local = glms_vec3_normalize(v_local);
+
+    // Stretch view.
+    float alpha = roughness * roughness;
+    vec3s v_h = (vec3s){alpha * v_local.x, alpha * v_local.y, v_local.z};
+    v_h = glms_vec3_normalize(v_h);
+
+    // Orthonormal basis around v_h.
+    vec3s t1;
+    if (v_h.z < 0.9999f)
+    {
+        t1 = glms_vec3_normalize(glms_vec3_cross((vec3s){0.0f, 0.0f, 1.0f}, v_h));
+    }
+    else
+    {
+        t1 = (vec3s){1.0f, 0.0f, 0.0f};
+    }
+    vec3s t2 = glms_vec3_cross(v_h, t1);
+
+    // Sample a point on a disk.
+    float r = sqrtf(u1);
+    float phi = TWO_PI * u2;
+    float t1p = r * cosf(phi);
+    float t2p = r * sinf(phi);
+
+    // Warp to the hemisphere.
+    float s = 0.5f * (1.0f + v_h.z);
+    t2p = (1.0f - s) * sqrtf(fmaxf(0.0f, 1.0f - t1p * t1p)) + s * t2p;
+
+    vec3s n_h = glms_vec3_add(
+        glms_vec3_add(glms_vec3_scale(t1, t1p), glms_vec3_scale(t2, t2p)),
+        glms_vec3_scale(v_h, sqrtf(fmaxf(0.0f, 1.0f - t1p * t1p - t2p * t2p))));
+
+    // Unstretch.
+    vec3s h_local = (vec3s){alpha * n_h.x, alpha * n_h.y, fmaxf(0.0f, n_h.z)};
+    h_local = glms_vec3_normalize(h_local);
+
+    // Back to world.
+    vec3s h_world = glms_vec3_add(
+        glms_vec3_add(glms_vec3_scale(tangent, h_local.x), glms_vec3_scale(bitangent, h_local.y)),
+        glms_vec3_scale(n, h_local.z));
+
+    return glms_vec3_normalize(h_world);
+}