Tune shadow perspective distortion (#12146)

* Pass perspective distortion parameters as uniforms
* Set all perspective bias parameters via ShadowRenderer
* Recalibrate perspective distortion and shadow range to render less shadow geometry with the same quality and observed shadow distance

2 files changed, 13 insertions, 13 deletions

diff --git a/client/shaders/object_shader/opengl_fragment.glsl b/client/shaders/object_shader/opengl_fragment.glsl
index edb9d2bb1..2b9a59cd7 100644
--- a/client/shaders/object_shader/opengl_fragment.glsl
+++ b/client/shaders/object_shader/opengl_fragment.glsl
@@ -43,17 +43,17 @@ const float fogShadingParameter = 1.0 / (1.0 - fogStart);
 #endif
 
 #ifdef ENABLE_DYNAMIC_SHADOWS
-const float bias0 = 0.9;
-const float zPersFactor = 0.5;
-const float bias1 = 1.0 - bias0 + 1e-6;
+uniform float xyPerspectiveBias0;
+uniform float xyPerspectiveBias1;
+uniform float zPerspectiveBias;
 
 vec4 getPerspectiveFactor(in vec4 shadowPosition)
 {
 
 	float pDistance = length(shadowPosition.xy);
-	float pFactor = pDistance * bias0 + bias1;
+	float pFactor = pDistance * xyPerspectiveBias0 + xyPerspectiveBias1;
 
-	shadowPosition.xyz *= vec3(vec2(1.0 / pFactor), zPersFactor);
+	shadowPosition.xyz *= vec3(vec2(1.0 / pFactor), zPerspectiveBias);
 
 	return shadowPosition;
 }
@@ -162,12 +162,12 @@ float getHardShadowDepth(sampler2D shadowsampler, vec2 smTexCoord, float realDis
 float getBaseLength(vec2 smTexCoord)
 {
 	float l = length(2.0 * smTexCoord.xy - 1.0);     // length in texture coords
-	return bias1 / (1.0 / l - bias0); 				 // return to undistorted coords
+	return xyPerspectiveBias1 / (1.0 / l - xyPerspectiveBias0); 				 // return to undistorted coords
 }
 
 float getDeltaPerspectiveFactor(float l)
 {
-	return 0.1 / (bias0 * l + bias1);                      // original distortion factor, divided by 10
+	return 0.1 / (xyPerspectiveBias0 * l + xyPerspectiveBias1);                      // original distortion factor, divided by 10
 }
 
 float getPenumbraRadius(sampler2D shadowsampler, vec2 smTexCoord, float realDistance, float multiplier)
@@ -477,8 +477,8 @@ void main(void)
 		vec3 shadow_color = vec3(0.0, 0.0, 0.0);
 		vec3 posLightSpace = getLightSpacePosition();
 
-		float distance_rate = (1 - pow(clamp(2.0 * length(posLightSpace.xy - 0.5),0.0,1.0), 20.0));
-		float f_adj_shadow_strength = max(adj_shadow_strength-mtsmoothstep(0.9,1.1,  posLightSpace.z  ),0.0);
+		float distance_rate = (1 - pow(clamp(2.0 * length(posLightSpace.xy - 0.5),0.0,1.0), 50.0));
+		float f_adj_shadow_strength = max(adj_shadow_strength-mtsmoothstep(0.9,1.1,  posLightSpace.z),0.0);
 
 		if (distance_rate > 1e-7) {
 	
diff --git a/client/shaders/object_shader/opengl_vertex.glsl b/client/shaders/object_shader/opengl_vertex.glsl
index ff0067302..55861b0e9 100644
--- a/client/shaders/object_shader/opengl_vertex.glsl
+++ b/client/shaders/object_shader/opengl_vertex.glsl
@@ -37,8 +37,8 @@ const vec3 artificialLight = vec3(1.04, 1.04, 1.04);
 varying float vIDiff;
 const float e = 2.718281828459;
 const float BS = 10.0;
-const float bias0 = 0.9;
-const float bias1 = 1.0 - bias0;
+uniform float xyPerspectiveBias0;
+uniform float xyPerspectiveBias1;
 
 #ifdef ENABLE_DYNAMIC_SHADOWS
 // custom smoothstep implementation because it's not defined in glsl1.2
@@ -116,9 +116,9 @@ void main(void)
 		// Distance from the vertex to the player
 		float distanceToPlayer = length(eyeToVertex - v_LightDirection * dot(eyeToVertex, v_LightDirection)) / f_shadowfar;
 		// perspective factor estimation according to the
-		float perspectiveFactor = distanceToPlayer * bias0 + bias1;
+		float perspectiveFactor = distanceToPlayer * xyPerspectiveBias0 + xyPerspectiveBias1;
 		float texelSize = f_shadowfar * perspectiveFactor * perspectiveFactor /
-				(f_textureresolution * bias1  - perspectiveFactor * bias0);
+				(f_textureresolution * xyPerspectiveBias1  - perspectiveFactor * xyPerspectiveBias0);
 		float slopeScale = clamp(pow(1.0 - cosLight*cosLight, 0.5), 0.0, 1.0);
 		normalOffsetScale = texelSize * slopeScale;