mip the specular cube properly

3 files changed, 142 insertions, 46 deletions

diff --git a/c2.cpp b/c2.cpp
index 2d4ad14..9d680e3 100644
--- a/c2.cpp
+++ b/c2.cpp
@@ -285,13 +285,36 @@ struct Env_Probe {
 	static constexpr int mip_count = 9;
 	Texture_Id cubemap[2];
 	Texture_Id cubemap_depth;
-	Texture_Id faces[2][6][mip_count];
+	Texture_Id faces_render[6];
+	Texture_Id faces[6][mip_count];
 	Sampler_Id sampler;
 	int cubemap_res;
-	int completed;
 	Staged_Buffer config;
+	Staged_Buffer face_cb[6][mip_count];
 	Shader* shader;
-	int src_binding, vert_binding;
+	int src_binding, vert_binding, face_binding;
+
+	struct Face_Cbuffer {
+		float dir[3];
+		float roughness;
+		float up[3];
+	};
+	v3f face_dirs[6] = {
+		v3f( 1.0f,  0.0f,  0.0f),
+		v3f(-1.0f,  0.0f,  0.0f),
+		v3f( 0.0f,  1.0f,  0.0f),
+		v3f( 0.0f, -1.0f,  0.0f),
+		v3f( 0.0f,  0.0f, -1.0f),
+		v3f( 0.0f,  0.0f,  1.0f)
+	};
+	v3f face_ups[6] = {
+		v3f(0.0f, 1.0f, 0.0f),
+		v3f(0.0f, 1.0f, 0.0f),
+		v3f(0.0f, 0.0f, 1.0f),
+		v3f(0.0f, 0.0f, -1.0f),
+		v3f(0.0f, 1.0f, 0.0f),
+		v3f(0.0f, 1.0f, 0.0f)
+	};
 
 	void init(Device* dev, Asset_Arena* assets, int res) {
 		int i;
@@ -345,22 +368,28 @@ struct Env_Probe {
 			int j;
 			int w = res;
 			int h = res;
+			faces_render[i] = dev->alias_texture(
+				cubemap[0],
+				"env cubemap face A",
+				texture_format_rgba16f,
+				Texture_Flags::colour_target |
+				Texture_Flags::sampleable,
+				w,
+				h,
+				1,
+				1,
+				1,
+				0,
+				i
+			);
 			for (j = 0; j < mip_count; j++) {
-				faces[0][i][j] = dev->alias_texture(
-					cubemap[0],
-					"env cubemap face A",
-					texture_format_rgba16f,
-					Texture_Flags::colour_target |
-					Texture_Flags::sampleable,
-					w,
-					h,
-					1,
-					1,
-					1,
-					j,
-					i
+				face_cb[i][j].init(
+					dev,
+					"env probe mip face cbuffer",
+					sizeof(Face_Cbuffer),
+					Buffer_Flags::constant_buffer
 				);
-				faces[1][i][j] = dev->alias_texture(
+				faces[i][j] = dev->alias_texture(
 					cubemap[1],
 					"env cubemap face B",
 					texture_format_rgba16f,
@@ -386,6 +415,7 @@ struct Env_Probe {
 		);
 		shader = (Shader*)assets->load("mip_spec.csh");
 		src_binding = shader->descriptor_binding("src");
+		face_binding = shader->descriptor_binding("c_face");
 		vert_binding = shader->binding_index("verts");
 		assert(src_binding >= 0);
 		assert(vert_binding >= 0);
@@ -396,9 +426,10 @@ struct Env_Probe {
 		for (i = 0; i < 6; i++) {
 			int j;
 			for (j = 0; j < mip_count; j++) {
-				dev->destroy_texture(faces[0][i][j]);
-				dev->destroy_texture(faces[1][i][j]);
+				dev->destroy_texture(faces[i][j]);
+				face_cb[i][j].destroy(dev);
 			}
+			dev->destroy_texture(faces_render[i]);
 		}
 		dev->destroy_texture(cubemap_depth);
 		dev->destroy_sampler(sampler);
@@ -417,25 +448,9 @@ struct Env_Probe {
 			0.1f,
 			1000.0f
 		).inverse();
-		v3f dirs[] = {
-			v3f( 1.0f,  0.0f,  0.0f),
-			v3f(-1.0f,  0.0f,  0.0f),
-			v3f( 0.0f,  1.0f,  0.0f),
-			v3f( 0.0f, -1.0f,  0.0f),
-			v3f( 0.0f,  0.0f, -1.0f),
-			v3f( 0.0f,  0.0f,  1.0f)
-		};
-		v3f ups[] = {
-			v3f(0.0f, 1.0f, 0.0f),
-			v3f(0.0f, 1.0f, 0.0f),
-			v3f(0.0f, 0.0f, 1.0f),
-			v3f(0.0f, 0.0f, -1.0f),
-			v3f(0.0f, 1.0f, 0.0f),
-			v3f(0.0f, 1.0f, 0.0f)
-		};
 		for (i = 0; i < 6; i++) {
 			Sky::Cbuffer& buf = bufs[i];
-			m4f view = m4f::lookat(v3f(0.0f), dirs[i], ups[i]);
+			m4f view = m4f::lookat(v3f(0.0f), face_dirs[i], face_ups[i]);
 			buf.iview = view.inverse();
 			buf.iprojection = iproj;
 		}
@@ -449,8 +464,21 @@ struct Env_Probe {
 		Context& ctx = dev->get_ctx();
 		update_cbuffer(dev);
 		for (i = 0; i < 6; i++) {
+			int j;
+			for (j = 0; j < mip_count; j++) {
+				Face_Cbuffer* cb = (Face_Cbuffer*)face_cb[i][j].map(dev);
+				cb->dir[0] = face_dirs[i].x;
+				cb->dir[1] = face_dirs[i].y;
+				cb->dir[2] = face_dirs[i].z;
+				cb->roughness = (float)j / (float)(mip_count - 1);
+				cb->up[0] = face_ups[i].x;
+				cb->up[1] = face_ups[i].y;
+				cb->up[2] = face_ups[i].z;
+				face_cb[i][j].unmap(dev);
+				face_cb[i][j].update(ctx);
+			}
 			pb.begin_rp();
-			pb.rp_target(faces[0][i][0], Clear_Mode::discard);
+			pb.rp_target(faces_render[i], Clear_Mode::discard);
 			pb.rp_depth_target(cubemap_depth, 1.0f);
 			sky.render_imp(
 				dev,
@@ -463,20 +491,23 @@ struct Env_Probe {
 				cubemap_res
 			);
 		}
-		completed = 0;
 		for (i = 0; i < 6; i++) {
 			int j;
 			for (j = 0; j < mip_count; j++) {
-				Texture& t = dev->get_texture(faces[completed ^ 1][i][j]);
+				Texture& t = dev->get_texture(faces[i][j]);
 				pb.begin_rp();
 				pb.rp_target(t.id, Clear_Mode::discard);
 				Render_Pass& pass = pb.build_rp();
 				pb.begin();
 				pb.viewport(0, 0, t.w, t.h);
 				pb.scissor(0, 0, t.w, t.h);
+				pb.cbuffer(
+					face_binding,
+					face_cb[i][j].gpuonly
+				);
 				pb.texture(
 					src_binding,
-					faces[completed][i][0],
+					cubemap[0],
 					sampler
 				);
 				pb.shader(shader->id);
@@ -495,11 +526,10 @@ struct Env_Probe {
 				ctx.submit(draw, pip, pass);
 			}
 		}
-		completed = 1;
 	}
 
 	Texture_Id get_cubemap() {
-		return cubemap[completed];
+		return cubemap[1];
 	}
 };
 
diff --git a/intermediate/mip_spec.glsl b/intermediate/mip_spec.glsl
index bddcbb0..519fee0 100644
--- a/intermediate/mip_spec.glsl
+++ b/intermediate/mip_spec.glsl
@@ -18,10 +18,27 @@ type: vec2
 name: uv
 type: vec2
 
+[struct]
+name: Face
+[variable]
+name: dir
+type: vec3
+[variable]
+name: roughness
+type: float
+[variable]
+name: up
+type: vec3
+
+[cbuffer]
+name: c_face
+type: Face
+stage: fragment
+
 [texture]
 name: src
 stage: fragment
-dimension: 2
+dimension: cube
 
 [target]
 name: colour
@@ -36,9 +53,58 @@ void main() {
 #endif
 
 #ifdef FRAGMENT_SHADER
+float ri(uint bits)  {
+	bits = (bits << 16u) | (bits >> 16u);
+	bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xaaaaaaaau) >> 1u);
+	bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xccccccccu) >> 2u);
+	bits = ((bits & 0x0f0f0f0fu) << 4u) | ((bits & 0xf0f0f0f0u) >> 4u);
+	bits = ((bits & 0x00ff00ffu) << 8u) | ((bits & 0xff00ff00u) >> 8u);
+	return float(bits) * 2.3283064365386963e-10;
+}
+
+vec2 hammersley(uint i, uint n) {
+	return vec2(float(i) / float(n), ri(i));
+}
+
+#define pi 3.14159265358979323846
+
+vec3 importance_sample_ggx(vec2 xi, float rough, vec3 n) {
+	float a = rough * rough;
+	float phi = 2 * pi * xi.x;
+	float ct = sqrt((1 - xi.y) / (1 + (a * a - 1) * xi.y));
+	float st = sqrt(1 - ct * ct);
+	vec3 h;
+	h.x = st * cos(phi);
+	h.y = st * sin(phi);
+	h.z = ct;
+	vec3 up = abs(n.z) < 0.999 ? vec3(0, 0, 1) : vec3(1, 0, 0);
+	vec3 tx = normalize(cross(up, n));
+	vec3 ty = cross(n, tx);
+	return tx * h.x + ty * h.y + n * h.z;
+}
+
+vec3 prefilter_env(float rough, vec3 n) {
+	vec3 c = 0.0.xxx;
+	int i, samples = 32;
+	float w = 1.0 / float(samples);
+	for (i = 0; i < samples; i++) {
+		vec2 coord = hammersley(i, samples);
+		vec3 s = importance_sample_ggx(coord, rough, n);
+		vec3 l = 2.0 * dot(n, s) * s - n;
+		c += (textureLod(src, l, 0.0).rgb * max(dot(n, l), 0.0)) * w;
+	}
+	return c;
+}
+
 void main() {
-	vec2 uv = interpolator.uv;
-	colour = texture(src, uv);
+	vec2 uv = interpolator.uv * 2.0 - 1.0;
+	vec3 n = c_face.dir;
+	vec3 u = c_face.up;
+	vec3 p1 = normalize(cross(n, u));
+	vec3 p2 = normalize(cross(n, p1));
+	vec3 uvw = uv.x * p1 + uv.y * p2;
+	n = normalize(n + uvw);
+	colour = vec4(prefilter_env(c_face.roughness, n), 1.0);
 }
 #endif
 
diff --git a/todo.txt b/todo.txt
index b090b4a..984a251 100644
--- a/todo.txt
+++ b/todo.txt
@@ -17,7 +17,7 @@ todo list
  - [ ] memory debug tool
  - [x] material system
  - [x] render a sky box
- - [ ] PBR + IBL
+ - [x] PBR + IBL
  - [ ] shadows
  - [ ] MSAA
  - [ ] GI