Use proper depth linear value

data/shaders/instanced_shadowref.frag

@@ -17,5 +17,5 @@ void main(void)
     vec4 col = texture(tex, uv);
 #endif
     if (col.a < 0.5) discard;
-    FragColor = vec4(gl_FragCoord.z);
+    FragColor = vec4((2. * gl_FragCoord.z - 1.) / gl_FragCoord.w);
 }

data/shaders/shadow.frag

@@ -2,5 +2,5 @@ out vec4 FragColor;
 
 void main()
 {
-    FragColor = vec4(gl_FragCoord.z);
+    FragColor = vec4((2. * gl_FragCoord.z - 1.) / gl_FragCoord.w);
 }

data/shaders/shadowref.frag

@@ -12,5 +12,5 @@ void main(void)
 {
     vec4 col = texture(tex, uv);
     if (col.a < 0.5) discard;
-    FragColor = vec4(gl_FragCoord.z);
+    FragColor = vec4((2. * gl_FragCoord.z - 1.) / gl_FragCoord.w);
 }

data/shaders/sunlightshadow.frag

@@ -30,7 +30,7 @@ float getShadowFactor(vec3 pos, float bias, int index)
 	);
 
 	vec4 shadowcoord = (ShadowViewProjMatrixes[index] * InverseViewMatrix * vec4(pos, 1.0));
-	shadowcoord /= shadowcoord.w;
+	shadowcoord.xy /= shadowcoord.w;
 	vec2 shadowtexcoord = shadowcoord.xy * 0.5 + 0.5;
 //	shadowcoord = (shadowcoord * 0.5) + vec3(0.5);
 
@@ -55,7 +55,7 @@ float getShadowFactor(vec3 pos, float bias, int index)
 //	return sum / 16.;
 
 	float z = texture(shadowtex, vec3(shadowtexcoord, float(index))).x;
-	float d = .5 * shadowcoord.z + .5;
+	float d = shadowcoord.z;
 	return min(exp(1024 *(z - d)), 1.);
 }
 

src/graphics/render_geometry.cpp

@@ -978,8 +978,6 @@ void IrrDriver::renderShadows()
     glDepthMask(GL_TRUE);
     glEnable(GL_DEPTH_TEST);
     glDisable(GL_BLEND);
-    glCullFace(GL_FRONT);
-    glEnable(GL_CULL_FACE);
     m_rtts->getShadowFBO().Bind();
 
     glClearColor(1., 1., 1., 1.);
@@ -1022,9 +1020,6 @@ void IrrDriver::renderShadows()
         }
     }
 
-    glCullFace(GL_BACK);
-    glDisable(GL_CULL_FACE);
-
     m_post_processing->renderGaussian6BlurLayer(m_rtts->getShadowFBO());
     glBindTexture(GL_TEXTURE_2D_ARRAY, m_rtts->getShadowFBO().getRTT()[0]);
     glGenerateMipmap(GL_TEXTURE_2D_ARRAY);