From e511e9c678eeb76906e75dbc92165e538d13546b Mon Sep 17 00:00:00 2001
From: Freya Murphy <freya@freyacat.org>
Date: Thu, 11 Dec 2025 22:10:52 -0500
Subject: ambient occlusion

---
 assets/fragment.glsl |   2 +
 assets/vertex.glsl   | 106 +++++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 96 insertions(+), 12 deletions(-)

(limited to 'assets')

diff --git a/assets/fragment.glsl b/assets/fragment.glsl
index 5ce136e..bb1eab2 100755
--- a/assets/fragment.glsl
+++ b/assets/fragment.glsl
@@ -1,6 +1,7 @@
 #version 330 core
 
 flat in uvec2 pass_data;
+in float pass_ao;
 
 out vec4 color;
 
@@ -18,5 +19,6 @@ void main(void)
 	uint block = (pass_data.x >> 28) & 15u;
 	uint face = (pass_data.x >> 25) & 7u;
 	float tint = TINT[face];
+	tint *= 1.0 - pow(pass_ao / 3.0, 1.2) * 0.65;
 	color = vec4(vec3(tint), 1);
 }
diff --git a/assets/vertex.glsl b/assets/vertex.glsl
index f4c3fde..78a479c 100755
--- a/assets/vertex.glsl
+++ b/assets/vertex.glsl
@@ -1,6 +1,6 @@
 #version 330 core
 
-layout (location = 0) in vec3 quad;
+layout (location = 0) in vec3 in_quad;
 
 layout (std140) uniform Matrices {
 	mat4 proj;
@@ -19,6 +19,13 @@ layout (std140) uniform Face {
 };
 
 flat out uvec2 pass_data;
+out float pass_ao;
+
+const mat3 ROT90 = mat3(
+	0.0,  0.0, 1.0,
+	0.0,  1.0, 0.0,
+	-1.0, 0.0, 0.0
+);
 
 uint get_half(int index)
 {
@@ -34,28 +41,98 @@ uvec2 get_data(int index)
 	return uvec2(lower, upper);
 }
 
+bool get_ao_rotate(uint data)
+{
+	vec4 ao;
+
+	ao.x = (data >> 0) & 3u;
+	ao.y = (data >> 2) & 3u;
+	ao.z = (data >> 4) & 3u;
+	ao.w = (data >> 6) & 3u;
+
+	float a = abs(ao.x - ao.w);
+	float b = abs(ao.y - ao.z);
+
+	return a > b;
+}
+
+float get_ao(uint data, uint face)
+{
+	vec4 ao;
+
+	ao.x = (data >> 0) & 3u;
+	ao.y = (data >> 2) & 3u;
+	ao.z = (data >> 4) & 3u;
+	ao.w = (data >> 6) & 3u;
+
+	switch (face) {
+		case 0u: // PX
+		case 2u: // PY
+		case 4u: // PZ
+			ao = ao.xywz;
+			if (get_ao_rotate(data))
+				ao = ao.wxyz;
+			break;
+		case 1u: // NX
+		case 3u: // NY
+		case 5u: // NZ
+			if (get_ao_rotate(data))
+				ao = ao.ywxz;
+			ao = ao.wzxy;
+			break;
+	}
+
+	return ao[gl_VertexID];
+}
+
+vec3 rotate(vec3 v, uint face)
+{
+	switch(face) {
+		case 0u: // PX
+		case 1u: // NX
+			v = vec3(v.x, v.z, -v.y + 1);
+			break;
+		case 2u: // PY
+		case 3u: // NY
+			v = vec3(-v.z + 1, v.y, v.x);
+			break;
+		case 4u: // PZ
+		case 5u: // NZ
+			v = vec3(v.y, -v.x + 1, v.z);
+			break;
+	}
+
+	return v;
+}
+
 vec3 get_quad(uint face, uint width, uint height)
 {
-	vec3 squad = quad;
-	squad.x *= width;
-	squad.y *= height;
+	vec3 quad = in_quad;
+	quad.x *= width;
+	quad.y *= height;
 
 	switch(face) {
 		case 0u: // PX
-			return squad.yzx + vec3(1, 0, 0);
+			quad = quad.yzx + vec3(1, 0, 0);
+			break;
 		case 1u: // NX
-			return squad.yxz;
+			quad = quad.yxz;
+			break;
 		case 2u: // PY
-			return squad.xyz + vec3(0, 1, 0);
+			quad = quad.xyz + vec3(0, 1, 0);
+			break;
 		case 3u: // NY
-			return squad.zyx;
+			quad = quad.zyx;
+			break;
 		case 4u: // PZ
-			return squad.zxy + vec3(0, 0, 1);
+			quad = quad.zxy + vec3(0, 0, 1);
+			break;
 		case 5u: // NZ
-			return squad.xzy;
+			quad = quad.xzy;
+			break;
 	}
-	// should not happen
-	return vec3(0);
+
+	return quad;
 }
 
 void main(void)
@@ -71,6 +148,8 @@ void main(void)
 
 	// get quad verts
 	vec3 quad = get_quad(face, width, height);
+	if (get_ao_rotate(data.y))
+		quad = rotate(quad, face);
 
 	// get position
 	vec3 position = vec3(x, y, z);
@@ -79,5 +158,8 @@ void main(void)
 
 	// draw
 	gl_Position = proj * view * vec4(position, 1.0);
+
+	// fragment input
 	pass_data = data;
+	pass_ao = get_ao(data.y, face);
 }
-- 
cgit v1.2.3-freya