rtx: add a bunch of ray bounces

while fps dips below 1, it still looks like modern art

ref_vk/TODO.md

@@ -4,9 +4,11 @@
 - [x] rtx: make projection matrix independent render global/current/static state
 - [x] rtx: model matrices
 - [x] rtx: light entities -- still not enough to enlight maps :(
+- [x] rtx: path tracing
 
 # Next
-- [ ] rtx: path tracing
+- [ ] rtx: control bounces with cvars
+- [ ] rtx: lower resolution framebuffer + upscale
 - [ ] rtx: textures
 - [ ] rtx: add fps
 	- [ ] better AS structure (fewer blases, etc)
@@ -15,7 +17,6 @@
 - [ ] rtx: some studio models have glitchy geometry
 
 # Planned
-- [ ] rtx: lower resolution framebuffer + upscale
 - [ ] dlight for flashlight seems to be broken
 - [ ] restore render debug labels
 - [ ] make 2nd commad buffer for resource upload

ref_vk/shaders/rtx.comp

@@ -66,14 +66,18 @@ void main() {
 	vec3 C = vec3(0.);
 	vec3 O = origin.xyz, D=direction.xyz;
 
+	vec3 kc = vec3(1.);
 	const float L = 10000.;
-	rayQueryEXT rayQuery;
-	rayQueryInitializeEXT(rayQuery, tlas, gl_RayFlagsOpaqueEXT, 0xff, O, 0., D, L);
-	while(rayQueryProceedEXT(rayQuery)) {}
-	const float l = rayQueryGetIntersectionTEXT(rayQuery, true);
-	if (rayQueryGetIntersectionTypeEXT(rayQuery, true) != gl_RayQueryCommittedIntersectionTriangleEXT) {
-		C = vec3(1., 0., 1.);
-	} else {
+	for (int bounce = 0; bounce < 4; ++bounce) {
+		rayQueryEXT rayQuery;
+		rayQueryInitializeEXT(rayQuery, tlas, gl_RayFlagsOpaqueEXT, 0xff, O, 0., D, L);
+		while(rayQueryProceedEXT(rayQuery)) {}
+		const float l = rayQueryGetIntersectionTEXT(rayQuery, true);
+		if (rayQueryGetIntersectionTypeEXT(rayQuery, true) != gl_RayQueryCommittedIntersectionTriangleEXT) {
+			C += kc * vec3(1., 0., 1.);
+			break;
+		}
+
 		vec3 pos = O+D*l;
 
 		//const int instance_index = rayQueryGetIntersectionInstanceIdEXT(rayQuery, true);
@@ -95,7 +99,6 @@ void main() {
 		const vec3 normal = normalize(transpose(inverse(mat3(transform))) * (n1 * (1. - bary.x - bary.y) + n2 * bary.x + n3 * bary.y));
 		// TODO rotate normal accroding to model matrix
 
-
 		const vec3 baseColor = vec3(1.);
 		rand01_state = fract((pos.x + pos.y + pos.z)/100.) + uv.x + uv.y + pc.t;
 		for (uint i = 0; i < num_lights; ++i) {
@@ -107,11 +110,11 @@ void main() {
 
 			// Find random point on a sphere
 			// TODO proper BRDF importance sampling and correct random point distribution
-			vec3 rnd = normalize(vec3(rand01()*2.-1., rand01()*2.-1., rand01()*2.-1.));
+			vec3 rnd = normalize(vec3(rand01(), rand01(), rand01())*2.-1.);
 			if (dot(rnd, pos - light_pos_r.xyz) < 0.) rnd = -rnd;
 
 			// TODO fudge this
-			const float light_r_scaler = 10.;
+			const float light_r_scaler = 2.;
 			const vec3 light_dir = light_pos_r.xyz - pos + rnd * light_pos_r.w / light_r_scaler;
 			const vec3 light_dir_norm = normalize(light_dir);
 			const float dot_ld_norm = dot(light_dir_norm, normal);
@@ -133,9 +136,19 @@ void main() {
 			const float r2 = light_pos_r.w * light_pos_r.w;
 			// TODO this is a bad approximation
 			const float attenuation = dlight_attenuation_const / (d2 + r2 * .5);
-			C += baseColor.rgb * light_color * dot_ld_norm * attenuation;
-		}
-	}
+			C += kc * baseColor.rgb * light_color * dot_ld_norm * attenuation;
+		} // for all lights
+
+		kc *= .9;
+		const float rough = .4;
+		O = pos + .01 * normal;
+		// TODO this is totally not correct
+		D = normalize(mix(
+				reflect(D, normal),
+				vec3(rand01(), rand01(), rand01())*2.-1.,
+				rough
+			));
+	} // for all bounces
 
 	imageStore(image, ivec2(gl_GlobalInvocationID.xy), vec4(C, 1.));
 }