port from perforce

hgplus/ShaderMinifier/tests/real/gfx monitor/ambiantocclusion.fs

@@ -0,0 +1,213 @@
+// FragmentProgram
+//
+// porting GLSL by kioku based on syoyo's AS3 Ambient Occlusion
+// [http://lucille.atso-net.jp/blog/?p=638]
+
+varying vec3 org,dir;
+
+struct Ray
+{
+	vec3 org;
+	vec3 dir;
+};
+struct Sphere
+{
+	vec3 center;
+	float radius;
+};
+struct Plane
+{
+	vec3 p;
+	vec3 n;
+};
+
+struct Intersection
+{
+    float t;
+    vec3 p;     // hit point
+    vec3 n;     // normal
+    int hit;
+};
+
+void shpere_intersect(Sphere s,  Ray ray, inout Intersection isect)
+{
+    // rs = ray.org - sphere.center
+    vec3 rs = ray.org - s.center;
+    float B = dot(rs, ray.dir);
+    float C = dot(rs, rs) - (s.radius * s.radius);
+    float D = B * B - C;
+
+    if (D > 0.0)
+    {
+		float t = -B - sqrt(D);
+		if ( (t > 0.0) && (t < isect.t) )
+		{
+			isect.t = t;
+			isect.hit = 1;
+
+			// calculate normal.
+			vec3 p = vec3(ray.org.x + ray.dir.x * t,
+						  ray.org.y + ray.dir.y * t,
+						  ray.org.z + ray.dir.z * t);
+			vec3 n = p - s.center;
+			n = normalize(n);
+			isect.n = n;
+			isect.p = p;
+		}
+	}
+}
+
+void plane_intersect(Plane pl, Ray ray, inout Intersection isect)
+{
+	// d = -(p . n)
+	// t = -(ray.org . n + d) / (ray.dir . n)
+	float d = -dot(pl.p, pl.n);
+	float v = dot(ray.dir, pl.n);
+
+	if (abs(v) < 1.0e-6)
+		return; // the plane is parallel to the ray.
+
+    float t = -(dot(ray.org, pl.n) + d) / v;
+
+    if ( (t > 0.0) && (t < isect.t) )
+    {
+		isect.hit = 1;
+		isect.t   = t;
+		isect.n   = pl.n;
+
+		vec3 p = vec3(ray.org.x + t * ray.dir.x,
+					  ray.org.y + t * ray.dir.y,
+					  ray.org.z + t * ray.dir.z);
+		isect.p = p;
+	}
+}
+
+Sphere sphere[3];
+Plane plane;
+void Intersect(Ray r, inout Intersection i)
+{
+	for (int c = 0; c < 3; c++)
+	{
+		shpere_intersect(sphere[c], r, i);
+	}
+	plane_intersect(plane, r, i);
+}
+
+void orthoBasis(out vec3 basis[3], vec3 n)
+{
+	basis[2] = vec3(n.x, n.y, n.z);
+	basis[1] = vec3(0.0, 0.0, 0.0);
+
+	if ((n.x < 0.6) && (n.x > -0.6))
+		basis[1].x = 1.0;
+	else if ((n.y < 0.6) && (n.y > -0.6))
+		basis[1].y = 1.0;
+	else if ((n.z < 0.6) && (n.z > -0.6))
+		basis[1].z = 1.0;
+	else
+		basis[1].x = 1.0;
+
+
+	basis[0] = cross(basis[1], basis[2]);
+	basis[0] = normalize(basis[0]);
+
+	basis[1] = cross(basis[2], basis[0]);
+	basis[1] = normalize(basis[1]);
+
+}
+
+int seed = 0;
+float random()
+{
+	seed = int(mod(float(seed)*1364.0+626.0, 509.0));
+	return float(seed)/509.0;
+}
+vec3 computeAO(inout Intersection isect)
+{
+	int i, j;
+    int ntheta = 8;
+    int nphi   = 8;
+    float eps  = 0.0001;
+
+    // Slightly move ray org towards ray dir to avoid numerical probrem.
+    vec3 p = vec3(isect.p.x + eps * isect.n.x,
+                  isect.p.y + eps * isect.n.y,
+                  isect.p.z + eps * isect.n.z);
+
+    // Calculate orthogonal basis.
+    vec3 basis[3];
+    orthoBasis(basis, isect.n);
+
+    float occlusion = 0.0;
+
+    for (j = 0; j < ntheta; j++)
+    {
+		for (i = 0; i < nphi; i++)
+		{
+			// Pick a random ray direction with importance sampling.
+			// p = cos(theta) / 3.141592
+			float r = random();
+			float phi = 2.0 * 3.141592 * random();
+
+			vec3 ref;
+			ref.x = cos(phi) * sqrt(1.0 - r);
+			ref.y = sin(phi) * sqrt(1.0 - r);
+			ref.z = sqrt(r);
+
+			// local -> global
+			vec3 rray;
+			rray.x = ref.x * basis[0].x + ref.y * basis[1].x + ref.z * basis[2].x;
+			rray.y = ref.x * basis[0].y + ref.y * basis[1].y + ref.z * basis[2].y;
+			rray.z = ref.x * basis[0].z + ref.y * basis[1].z + ref.z * basis[2].z;
+
+			vec3 raydir = vec3(rray.x, rray.y, rray.z);
+
+			Ray ray;
+			ray.org = p;
+			ray.dir = raydir;
+
+			Intersection occIsect;
+			occIsect.hit = 0;
+			occIsect.t = 1.0e+30;
+			occIsect.n = occIsect.p = vec3(0, 0, 0);
+			Intersect(ray, occIsect);
+			if (occIsect.hit != 0)
+				occlusion += 1.0;
+		}
+	}
+
+	// [0.0, 1.0]
+	occlusion = (float(ntheta * nphi) - occlusion) / float(ntheta * nphi);
+	return vec3(occlusion, occlusion, occlusion);
+}
+
+void main()
+{
+	sphere[0].center = vec3(-2.0, 0.0, -3.5);
+	sphere[0].radius = 0.5;
+	sphere[1].center = vec3(-0.5, 0.0, -3.0);
+	sphere[1].radius = 0.5;
+	sphere[2].center = vec3(1.0, 0.0, -2.2);
+	sphere[2].radius = 0.5;
+	plane.p = vec3(0,-0.5, 0);
+	plane.n = vec3(0, 1.0, 0);
+	
+	Intersection i;
+	i.hit = 0;
+	i.t = 1.0e+30;
+	i.n = i.p = vec3(0, 0, 0);
+		
+	Ray r;
+	r.org = org;
+	r.dir = normalize(dir);
+	seed = int(mod(dir.x * dir.y * 4525434.0, 65536.0));
+	
+	vec4 col = vec4(0,0,0,0);
+	Intersect(r, i);
+	if (i.hit != 0)
+	{
+		col.rgb = computeAO(i);
+	}
+	
+	gl_FragColor = col;
+}