From cc7f95163c29a19d6905e2e99a76a62fbbd63578 Mon Sep 17 00:00:00 2001
From: Vincent Lejeune <vljn@ovi.com>
Date: Tue, 9 Dec 2014 19:00:21 +0100
Subject: [PATCH] Simplify sunlight shadow shader.

---
 data/shaders/sunlightshadow.frag | 79 ++++++++++----------------------
 1 file changed, 23 insertions(+), 56 deletions(-)

diff --git a/data/shaders/sunlightshadow.frag b/data/shaders/sunlightshadow.frag
index b375be90c..47abf616c 100644
--- a/data/shaders/sunlightshadow.frag
+++ b/data/shaders/sunlightshadow.frag
@@ -29,35 +29,27 @@ vec3 getMostRepresentativePoint(vec3 direction, vec3 R, float angularRadius)
     return (DdotR < d) ? normalize(d * D + normalize (S) * r) : R;
 }
 
-float getShadowFactor(vec3 pos, float bias, int index)
+float getShadowFactor(vec3 pos, int index)
 {
+    vec4 shadowcoord = (ShadowViewProjMatrixes[index] * InverseViewMatrix * vec4(pos, 1.0));
+    shadowcoord.xy /= shadowcoord.w;
+    vec2 shadowtexcoord = shadowcoord.xy * 0.5 + 0.5;
 
-	vec2 shadowoffset[4] = vec2[](
-		vec2(-1., -1.),
-		vec2(-1., 1.),
-		vec2(1., -1.),
-		vec2(1., 1.)
-	);
-
-	vec4 shadowcoord = (ShadowViewProjMatrixes[index] * InverseViewMatrix * vec4(pos, 1.0));
-	shadowcoord.xy /= shadowcoord.w;
-	vec2 shadowtexcoord = shadowcoord.xy * 0.5 + 0.5;
-
-	float z = texture(shadowtex, vec3(shadowtexcoord, float(index))).x;
-	float d = shadowcoord.z;
-	return min(pow(exp(-32. * d) * z, 8.), 1.);
+    float z = texture(shadowtex, vec3(shadowtexcoord, float(index))).x;
+    float d = shadowcoord.z;
+    return min(pow(exp(-32. * d) * z, 8.), 1.);
 }
 
 void main() {
     vec2 uv = gl_FragCoord.xy / screen;
-	float z = texture(dtex, uv).x;
-	vec4 xpos = getPosFromUVDepth(vec3(uv, z), InverseProjectionMatrix);
+    float z = texture(dtex, uv).x;
+    vec4 xpos = getPosFromUVDepth(vec3(uv, z), InverseProjectionMatrix);
 
-	vec3 norm = normalize(DecodeNormal(2. * texture(ntex, uv).xy - 1.));
+    vec3 norm = normalize(DecodeNormal(2. * texture(ntex, uv).xy - 1.));
     float roughness =texture(ntex, uv).z;
     vec3 eyedir = -normalize(xpos.xyz);
 
-	// Normalized on the cpu
+    // Normalized on the cpu
     vec3 L = direction;
 
     float NdotL = clamp(dot(norm, L), 0., 1.);
@@ -69,43 +61,18 @@ void main() {
     vec3 Specular = SpecularBRDF(norm, eyedir, Lightdir, col, roughness) * NdotL;
 
 
-	vec3 outcol = NdotL * col;
+    vec3 outcol = NdotL * col;
 
 
-	// Shadows
-	float bias = 0.005 * tan(acos(NdotL)); // According to the slope
-	bias = clamp(bias, 0., 0.01);
-	float factor;
-	if (xpos.z < split0)
-		factor = getShadowFactor(xpos.xyz, bias, 0);
-/*	else if (xpos.z < 6.)
-	{
-		float a = getShadowFactor(xpos.xyz, bias, 0), b = getShadowFactor(xpos.xyz, bias, 1);
-		factor = mix(a, b, (xpos.z - 5.));
-	}*/
-	else if (xpos.z < split1)
-		factor = getShadowFactor(xpos.xyz, bias, 1);
-/*	else if (xpos.z < 21.)
-	{
-		float a = getShadowFactor(xpos.xyz, bias, 1), b = getShadowFactor(xpos.xyz, bias, 2);
-		factor = mix(a, b, (xpos.z - 20.));
-	}*/
-	else if (xpos.z < split2)
-		factor = getShadowFactor(xpos.xyz, bias, 2);
-/*	else if (xpos.z < 55.)
-	{
-		float a = getShadowFactor(xpos.xyz, bias, 2), b = getShadowFactor(xpos.xyz, bias, 3);
-		factor = mix(a, b, (xpos.z - 50.) / 5.);
-	}*/
-	else if (xpos.z < splitmax)
-		factor = getShadowFactor(xpos.xyz, bias, 3);
-/*	else if (xpos.z < 150.)
-	{
-		factor = mix(getShadowFactor(xpos.xyz, bias, 3), 1., (xpos.z - 145.) / 5.);
-	}*/
-	else
-		factor = 1.;
-	Diff = vec4(factor * NdotL * col, 1.);
-	Spec = vec4(factor * Specular, 1.);
-	return;
+    // Shadows
+    int shadowtex_index = 0;
+    shadowtex_index += (xpos.z >= split0) ? 1 : 0;
+    shadowtex_index += (xpos.z >= split1) ? 1 : 0;
+    shadowtex_index += (xpos.z >= split2) ? 1 : 0;
+
+    float factor = getShadowFactor(xpos.xyz, shadowtex_index);
+    factor = (xpos.z > splitmax) ? 1. : factor;
+
+    Diff = vec4(factor * NdotL * col, 1.);
+    Spec = vec4(factor * Specular, 1.);
 }