Reuse normal offset calculation for nodes

1 files changed, 15 insertions, 3 deletions

diff --git a/client/shaders/nodes_shader/opengl_vertex.glsl b/client/shaders/nodes_shader/opengl_vertex.glsl
index d316930b2..95cd138a8 100644
--- a/client/shaders/nodes_shader/opengl_vertex.glsl
+++ b/client/shaders/nodes_shader/opengl_vertex.glsl
@@ -45,6 +45,8 @@ varying float nightRatio;
 const vec3 artificialLight = vec3(1.04, 1.04, 1.04);
 const float e = 2.718281828459;
 const float BS = 10.0;
+const float bias0 = 0.9;
+const float bias1 = 1.0 - bias0;
 
 #ifdef ENABLE_DYNAMIC_SHADOWS
 // custom smoothstep implementation because it's not defined in glsl1.2
@@ -195,10 +197,20 @@ void main(void)
 #ifdef ENABLE_DYNAMIC_SHADOWS
 	vec3 nNormal = normalize(vNormal);
 	cosLight = dot(nNormal, -v_LightDirection);
-	float texelSize = 767.0 / f_textureresolution;
-	float slopeScale = clamp(1.0 - abs(cosLight), 0.0, 1.0);
-	normalOffsetScale = texelSize * slopeScale;
 	
+	// Calculate normal offset scale based on the texel size adjusted for 
+	// curvature of the SM texture. This code must be change together with
+	// getPerspectiveFactor or any light-space transformation.
+	vec3 eyeToVertex = worldPosition - eyePosition + cameraOffset;
+	// 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 texelSize = f_shadowfar * perspectiveFactor * perspectiveFactor /
+			(f_textureresolution * bias1  - perspectiveFactor * bias0);
+	float slopeScale = clamp(pow(1.0 - cosLight*cosLight, 0.5), 0.0, 1.0);
+	normalOffsetScale = texelSize * slopeScale;
+
 	if (f_timeofday < 0.2) {
 		adj_shadow_strength = f_shadow_strength * 0.5 *
 			(1.0 - mtsmoothstep(0.18, 0.2, f_timeofday));