Fix #5067 (#5071)

* Blur shadows by distance

* Copy from Bevy

data/shaders/sunlightshadow.frag

@@ -11,6 +11,7 @@ uniform float split1;
 uniform float split2;
 uniform float splitmax;
 uniform float shadow_res;
+uniform float overlap_proportion;
 
 uniform vec3 sundirection;
 uniform vec3 sun_color;
@@ -30,25 +31,56 @@ out vec4 Spec;
 #stk_include "utils/getPosFromUVDepth.frag"
 #stk_include "utils/SunMRP.frag"
 
-float getShadowFactor(vec3 pos, int index)
+// https://web.archive.org/web/20230210095515/http://the-witness.net/news/2013/09/shadow-mapping-summary-part-1
+float getShadowFactor(vec3 pos, int index, float bias)
 {
     vec4 shadowcoord = (u_shadow_projection_view_matrices[index] * u_inverse_view_matrix * vec4(pos, 1.0));
     shadowcoord.xy /= shadowcoord.w;
     vec2 shadowtexcoord = shadowcoord.xy * 0.5 + 0.5;
-    //float d = .5 * shadowcoord.z + .5;
-    float d = .5 * shadowcoord.z + .5 - 1. / (shadow_res * 5.);
+    float d = .5 * shadowcoord.z + .5 - bias;
 
-    float result = 0.;
+    vec2 uv = shadowtexcoord * shadow_res;
+    vec2 base_uv = floor(uv + 0.5);
+    float s = (uv.x + 0.5 - base_uv.x);
+    float t = (uv.y + 0.5 - base_uv.y);
+    base_uv -= 0.5;
+    base_uv /= shadow_res;
 
-    for (float i = -1.; i <= 1.; i += 1.)
-    {
-        for (float j = -1.; j <= 1.; j += 1.)
-        {
-            result += texture(shadowtex, vec4(shadowtexcoord + vec2(i,j) / shadow_res, float(index), d));
-        }
-    }
+    float uw0 = (4.0 - 3.0 * s);
+    float uw1 = 7.0;
+    float uw2 = (1.0 + 3.0 * s);
+
+    float u0 = (3.0 - 2.0 * s) / uw0 - 2.0;
+    float u1 = (3.0 + s) / uw1;
+    float u2 = s / uw2 + 2.0;
+
+    float vw0 = (4.0 - 3.0 * t);
+    float vw1 = 7.0;
+    float vw2 = (1.0 + 3.0 * t);
+
+    float v0 = (3.0 - 2.0 * t) / vw0 - 2.0;
+    float v1 = (3.0 + t) / vw1;
+    float v2 = t / vw2 + 2.0;
+
+    float sum = 0.0;
+
+    sum += uw0 * vw0 * texture(shadowtex, vec4(base_uv + (vec2(u0, v0) / shadow_res), float(index), d));
+    sum += uw1 * vw0 * texture(shadowtex, vec4(base_uv + (vec2(u1, v0) / shadow_res), float(index), d));
+    sum += uw2 * vw0 * texture(shadowtex, vec4(base_uv + (vec2(u2, v0) / shadow_res), float(index), d));
+
+    sum += uw0 * vw1 * texture(shadowtex, vec4(base_uv + (vec2(u0, v1) / shadow_res), float(index), d));
+    sum += uw1 * vw1 * texture(shadowtex, vec4(base_uv + (vec2(u1, v1) / shadow_res), float(index), d));
+    sum += uw2 * vw1 * texture(shadowtex, vec4(base_uv + (vec2(u2, v1) / shadow_res), float(index), d));
 
-    return result / 9.;
+    sum += uw0 * vw2 * texture(shadowtex, vec4(base_uv + (vec2(u0, v2) / shadow_res), float(index), d));
+    sum += uw1 * vw2 * texture(shadowtex, vec4(base_uv + (vec2(u1, v2) / shadow_res), float(index), d));
+    sum += uw2 * vw2 * texture(shadowtex, vec4(base_uv + (vec2(u2, v2) / shadow_res), float(index), d));
+
+    return sum / 144.0;
+}
+
+float blend_start(float x) {
+    return x * (1.0 - overlap_proportion);
 }
 
 void main() {
@@ -68,16 +100,30 @@ void main() {
 
     // Shadows
     float factor;
-    if (xpos.z < split0)
-        factor = getShadowFactor(xpos.xyz, 0);
-    else if (xpos.z < split1)
-        factor = getShadowFactor(xpos.xyz, 1);
-    else if (xpos.z < split2)
-        factor = getShadowFactor(xpos.xyz, 2);
-    else if (xpos.z < splitmax)
-        factor = getShadowFactor(xpos.xyz, 3);
-    else
+    float bias = max(1.0 - NdotL, .2) / shadow_res;
+    if (xpos.z < split0) {
+        factor = getShadowFactor(xpos.xyz, 0, bias);
+        if (xpos.z > blend_start(split0)) {
+            factor = mix(factor, getShadowFactor(xpos.xyz, 1, bias), (xpos.z - blend_start(split0)) / split0 / overlap_proportion);
+        }
+    } else if (xpos.z < split1) {
+        factor = getShadowFactor(xpos.xyz, 1, bias);
+        if (xpos.z > blend_start(split1)) {
+            factor = mix(factor, getShadowFactor(xpos.xyz, 2, bias), (xpos.z - blend_start(split1)) / split1 / overlap_proportion);
+        }
+    } else if (xpos.z < split2) {
+        factor = getShadowFactor(xpos.xyz, 2, bias);
+        if (xpos.z > blend_start(split2)) {
+            factor = mix(factor, getShadowFactor(xpos.xyz, 3, bias), (xpos.z - blend_start(split2)) / split2 / overlap_proportion);
+        }
+    } else if (xpos.z < splitmax) {
+        factor = getShadowFactor(xpos.xyz, 3, bias);
+        if (xpos.z > blend_start(splitmax)) {
+            factor = mix(factor, 1.0, (xpos.z - blend_start(splitmax)) / splitmax / overlap_proportion);
+        }
+    } else {
         factor = 1.;
+    }
 
     Diff = vec4(factor * NdotL * Diffuse * sun_color, 1.);
     Spec = vec4(factor * NdotL * Specular * sun_color, 1.);

src/graphics/lighting_passes.cpp

@@ -201,7 +201,7 @@ class DegradedIBLShader : public TextureShader<DegradedIBLShader, 1>
 // ============================================================================
 class ShadowedSunLightShaderPCF : public TextureShader<ShadowedSunLightShaderPCF,
                                                        3,  float, float, float,
-                                                       float, float,
+                                                       float, float, float,
                                                        core::vector3df, video::SColorf>
 {
 public:
@@ -215,7 +215,7 @@ class ShadowedSunLightShaderPCF : public TextureShader<ShadowedSunLightShaderPCF
                            1, "dtex", ST_NEAREST_FILTERED,
                            8, "shadowtex", ST_SHADOW_SAMPLER);
         assignUniforms("split0", "split1", "split2", "splitmax", "shadow_res",
-            "sundirection", "sun_color");
+            "overlap_proportion", "sundirection", "sun_color");
     }   // ShadowedSunLightShaderPCF
     // ------------------------------------------------------------------------
     void render(GLuint normal_depth_texture,
@@ -232,6 +232,7 @@ class ShadowedSunLightShaderPCF : public TextureShader<ShadowedSunLightShaderPCF
                             ShadowMatrices::m_shadow_split[3],
                             ShadowMatrices::m_shadow_split[4],
                             float(UserConfigParams::m_shadows_resolution),
+                            ShadowMatrices::m_shadow_overlap_proportion,
                             direction, col);
 
     }    // render

src/graphics/post_processing.cpp

@@ -77,26 +77,6 @@ class Gaussian3HBlurShader : public TextureShader<Gaussian3HBlurShader, 1,
     }   // render
 };   // Gaussian3HBlurShader
 
-// ============================================================================
-class ComputeShadowBlurVShader : public TextureShader<ComputeShadowBlurVShader, 1,
-                                               core::vector2df,
-                                               std::vector<float> >
-{
-public:
-    GLuint m_dest_tu;
-    ComputeShadowBlurVShader()
-    {
-#if !defined(USE_GLES2)
-        loadProgram(OBJECT, GL_COMPUTE_SHADER, "blurshadowV.comp");
-        m_dest_tu = 1;
-        assignUniforms("pixel", "weights");
-        assignSamplerNames(0, "source", ST_NEARED_CLAMPED_FILTERED);
-        assignTextureUnit(m_dest_tu, "dest");
-#endif
-    }   // ComputeShadowBlurVShader
-
-};   // ComputeShadowBlurVShader
-
 // ============================================================================
 class Gaussian6VBlurShader : public TextureShader<Gaussian6VBlurShader, 1,
                                            core::vector2df, float>
@@ -174,23 +154,6 @@ class ComputeGaussian6HBlurShader : public TextureShader<ComputeGaussian6HBlurSh
         assignTextureUnit(m_dest_tu, "dest");
     }   // ComputeGaussian6HBlurShader
 };   // ComputeGaussian6HBlurShader
-
-// ============================================================================
-class ComputeShadowBlurHShader : public TextureShader<ComputeShadowBlurHShader, 1,
-                                               core::vector2df,
-                                               std::vector<float> >
-{
-public:
-    GLuint m_dest_tu;
-    ComputeShadowBlurHShader()
-    {
-        loadProgram(OBJECT, GL_COMPUTE_SHADER, "blurshadowH.comp");
-        m_dest_tu = 1;
-        assignUniforms("pixel", "weights");
-        assignSamplerNames(0, "source", ST_NEARED_CLAMPED_FILTERED);
-        assignTextureUnit(m_dest_tu, "dest");
-    }   // ComputeShadowBlurHShader
-};   // ComputeShadowBlurHShader
 #endif
 
 // ============================================================================

src/graphics/shadow_matrices.cpp

@@ -39,7 +39,8 @@
 #define MAX2(a, b) ((a) > (b) ? (a) : (b))
 #define MIN2(a, b) ((a) > (b) ? (b) : (a))
 
-float ShadowMatrices:: m_shadow_split[5] = { 1., 5., 20., 50., 150 };
+float ShadowMatrices:: m_shadow_split[5] = { 1., 5., 20., 60., 150 };
+float ShadowMatrices:: m_shadow_overlap_proportion = 0.2;
 
 // ============================================================================
 class ViewFrustrumShader : public Shader<ViewFrustrumShader, video::SColor, int>
@@ -236,9 +237,9 @@ void ShadowMatrices::computeMatrixesAndCameras(scene::ICameraSceneNode *const ca
         float NearValues[] =
         {
             ShadowMatrices::m_shadow_split[0],
-            ShadowMatrices::m_shadow_split[1],
-            ShadowMatrices::m_shadow_split[2],
-            ShadowMatrices::m_shadow_split[3]
+            ShadowMatrices::m_shadow_split[1] * (1.0f - m_shadow_overlap_proportion),
+            ShadowMatrices::m_shadow_split[2] * (1.0f - m_shadow_overlap_proportion),
+            ShadowMatrices::m_shadow_split[3] * (1.0f - m_shadow_overlap_proportion)
         };
 
         // Shadow Matrixes and cameras

src/graphics/shadow_matrices.hpp

@@ -40,6 +40,7 @@ class ShadowMatrices
 {
 public:
     static float m_shadow_split[5];
+    static float m_shadow_overlap_proportion;
 
 private:
     std::vector<core::matrix4> m_sun_ortho_matrices;