+ | Accumulation texture

shaders/compute.glsl

@@ -1,11 +1,10 @@
 #version 430 core
-#include "shaders/utils.glsl"
 
-// Work group dimensions
+#include "shaders/random.glsl"
+
 layout(local_size_x = 16, local_size_y = 16) in;
-
-// Output image
 layout(binding = 0, rgba32f) uniform image2D outputImage;
+layout(binding = 1, rgba32f) uniform image2D accumulationImage;
 
 struct GPUObject {
 	vec3    position;       // 12 + 4
@@ -31,53 +30,100 @@ uniform int		u_frameCount;
 vec3 lightPos = vec3(5.0, 5.0, 5.0);
 vec3 lightColor = vec3(1.0, 1.0, 1.0);
 
-struct Ray {
+struct Ray
+{
 	vec3 origin;
 	vec3 direction;
 };
 
-bool intersectSphere(Ray ray, vec3 center, float radius, out float t)
+struct hitInfo
 {
-	vec3 oc = ray.origin - center;
+	float	t;
+	vec3	normal;
+	vec3	position;
+	int		obj_index;
+};
+
+bool intersectSphere(Ray ray, GPUObject obj, out hitInfo hit)
+{
+	vec3 oc = ray.origin - obj.position;
 	float a = dot(ray.direction, ray.direction);
 	float b = 2.0 * dot(oc, ray.direction);
-	float c = dot(oc, oc) - radius * radius;
+	float c = dot(oc, oc) - obj.radius * obj.radius;
 	float discriminant = b * b - 4.0 * a * c;
 
-	if (discriminant < 0.0) {
+	if (discriminant < 0.0)
 		return false;
-	}
-	float t1 = (-b - sqrt(discriminant)) / (2.0 * a);
-	if (t1 > 0.001) {
-		t = t1;
-		return true;
-	}
-	return false;
+
+	float t = (-b - sqrt(discriminant)) / (2.0 * a);
+	if (t < 0.0)
+		t = (-b + sqrt(discriminant)) / (2.0 * a);
+
+	hit.t = t;
+	hit.position = ray.origin + ray.direction * t;
+	hit.normal = normalize(hit.position - obj.position);
+
+	return (true);
 }
 
-vec3    pathtrace(Ray ray)
+hitInfo	trace_ray(Ray ray)
 {
-	vec3	color = vec3(0.0);
-	vec3	light = vec3(0.0);
+	hitInfo hit;
+	hit.t = 1e30;
+	hit.obj_index = -1;
 
-	float	closest_t = 1e30;
 	for (int i = 0; i < u_objectsNum; i++)
 	{
-		float t;
-		if (intersectSphere(ray, objects[i].position, objects[i].radius, t))
-		{
-			if (t < closest_t)
-			{
-				closest_t = t;
+		GPUObject obj = objects[i];
 
-				vec3 hitPoint = ray.origin + t * ray.direction;
-				vec3 normal = normalize(hitPoint - objects[i].position);
-				
-				color = objects[i].color * normal.y;
+		hitInfo tempHit;
+		if (intersectSphere(ray, obj, tempHit))
+		{
+			if (tempHit.t > 0.0f && tempHit.t < hit.t)
+			{
+				hit.t = tempHit.t;
+				hit.obj_index = i;
+				hit.position = tempHit.position;
+				hit.normal = tempHit.normal;
 			}
 		}
 	}
-	return (color);
+
+	return (hit);
+}
+
+vec3    pathtrace(Ray ray, vec2 random)
+{
+	vec3	color = vec3(1.0);
+	vec3	light = vec3(0.0);
+
+	float	closest_t = 1e30;
+	for (int i = 0; i < 10; i++)
+	{
+		hitInfo hit = trace_ray(ray);
+		if (hit.obj_index == -1)
+		{
+			light += vec3(0); //ambient color 
+			break;
+		}
+
+		GPUObject obj = objects[hit.obj_index];
+
+		color *= obj.color;
+		if (obj.emission > 0.0)
+		{
+			light += obj.emission * obj.color;
+			break;
+		}
+
+		ray.origin = hit.position + hit.normal * 0.001;
+		//cosine weighted importance sampling
+		vec3 unit_sphere = normalize(randomVec3Mixed(random, u_frameCount, -1.0, 1.0));
+		if (dot(unit_sphere, hit.normal) < 0.0)
+			unit_sphere = -unit_sphere;
+		ray.direction = normalize(hit.normal + unit_sphere);
+	}
+	return (color * light);
 }
 
 void main() {
@@ -97,8 +143,13 @@ void main() {
 	rayDirection = normalize(rayDirection);
 	Ray ray = Ray(u_cameraPosition, rayDirection);
 
-	vec3 color = pathtrace(ray);
+	vec3 color = pathtrace(ray, uv);
 
-	imageStore(outputImage, pixelCoords, vec4(randomVec3(uv, u_frameCount), 1.0));
+	vec4 accum = imageLoad(accumulationImage, pixelCoords);
+    accum.rgb = accum.rgb * float(u_frameCount) / float(u_frameCount + 1) + color / float(u_frameCount + 1);
+    accum.a = 1.0;
+    
+    imageStore(accumulationImage, pixelCoords, accum);
+    imageStore(outputImage, pixelCoords, accum);
 }
 

shaders/random.glsl

@@ -0,0 +1,28 @@
+
+float seed = 1.0;
+float getRandom(vec2 uv, int frameCount)
+{
+    float seed = dot(uv, vec2(12.9898, 78.233)) + float(frameCount);
+    return fract(sin(seed) * 43758.5453);
+}
+vec3 randomVec3(vec2 uv, int frameCount)
+{
+    return vec3(
+        getRandom(uv + vec2(0.1, 0.1), frameCount),
+        getRandom(uv + vec2(0.2, 0.2), frameCount),
+        getRandom(uv + vec2(0.3, 0.3), frameCount)
+    );
+}
+
+vec3 randomVec3Mixed(vec2 uv, int frameCount, float min_val, float max_val)
+{
+    float randomX = getRandom(uv + vec2(0.1, 0.1), frameCount);
+    float randomY = getRandom(uv + vec2(0.2, 0.2), frameCount);
+    float randomZ = getRandom(uv + vec2(0.3, 0.3), frameCount);
+    
+    return vec3(
+        mix(min_val, max_val, randomX),
+        mix(min_val, max_val, randomY),
+        mix(min_val, max_val, randomZ)
+    );
+}

shaders/utils.glsl

@@ -1,15 +0,0 @@
-
-float seed = 1.0;
-float getRandom(vec2 uv, int frameCount)
-{
-    float seed = dot(uv, vec2(12.9898, 78.233)) + float(frameCount);
-    return fract(sin(seed) * 43758.5453);
-}
-vec3 randomVec3(vec2 uv, int frameCount)
-{
-    return vec3(
-        getRandom(uv + vec2(0.1, 0.1), frameCount),
-        getRandom(uv + vec2(0.2, 0.2), frameCount),
-        getRandom(uv + vec2(0.3, 0.3), frameCount)
-    );
-}