feat: added soft shadows without multi ray casts

sdf.fs

@@ -6,23 +6,46 @@ in vec2 texCoords;
 
 uniform float aspect;
 
-vec3 center = vec3(0.0,0.0,20.0);
+vec3 center = vec3(0.0,-4.0,20.0);
 float radius = 5.0;
 
 float planeHeight = -7.0;
 
+struct SmallHit {
+    float min;
+    float len;
+    bool firstHP;
+};
+
 struct Ray {
     vec3 dir;
     vec3 pos;
     float min;
     float len;
+    SmallHit small;
     vec3 color;
 };
 
-Ray applyMin(Ray ray) {
+Ray createRay(vec3 dir, vec3 pos){
-    vec3 off = ray.dir * ray.min;
+    return Ray(dir, pos, .0, .0, SmallHit(80.,0.,false), vec3(.0));
+}
+
+Ray applyMin(Ray ray, float min) {
+    vec3 off = ray.dir * min;
     ray.pos = ray.pos + off;
-    ray.len = ray.len +  ray.min;
+    ray.len = ray.len +  min;
+
+    if( (min < ray.min) && !ray.small.firstHP ){
+        ray.small.firstHP = true;
+    }
+
+    ray.min = min;
+
+    if((ray.min < ray.small.min) && ray.small.firstHP){
+        ray.small.min = ray.min;
+        ray.small.len = ray.len;
+    }
+    
     return ray;
 }
 
@@ -38,18 +61,15 @@ float sphereMin(vec3 pos){
 Ray minFn(Ray ray){
     float sp = sphereMin(ray.pos);
     float pl = planeMin(ray.pos);
-
+    float min;
-
-    
-
     if (sp < pl){
         ray.color = vec3(1.0, 0.5, 0.2);
-        ray.min = sp;
+        min = sp;
     } else {
         ray.color = vec3(0.2, 0.3, 0.3);
-        ray.min = pl;
+        min = pl;
     }
-    return applyMin(ray);
+    return applyMin(ray,min);
     }
 
 float minFn(vec3 pos){
@@ -67,7 +87,7 @@ Ray march(Ray ray){
     //ray.min = minFn(ray.pos);
     ray = minFn(ray);
     int c = 0;
-    while(( c < 200) && (ray.min < 100.0f) && (ray.min > 0.1f) ) {
+    while(( c < 200) && (ray.min < 100.0f) && (ray.min > 0.01f) ) {
         ray = minFn(ray);    
         c++;
     }
@@ -93,8 +113,7 @@ void main()
     vec3 dir = vec3((texCoords - 0.5)*2,1.0);
     dir.x *= aspect;
     vec3 pos = dir;
-    Ray ray = Ray(normalize(dir),pos,.0,.0,vec3(.0));
+    Ray ray = createRay(normalize(dir),pos);
-
     ray = march(ray);
 
     vec3 normal = calcNormal(ray);
@@ -104,28 +123,26 @@ void main()
 
     float shLeve = 1.0;
  
-    vec2 offsets[8] = vec2[](
-        vec2( -0.94201624, -0.39906216 ),
-        vec2( 0.94558609, -0.76890725 ),
-        vec2( -0.094184101, -0.92938870 ),
-        vec2( 0.34495938, 0.29387760 ),
-        vec2( 0.94201624, 0.39906216 ),
-        vec2( -0.94558609, 0.76890725 ),
-        vec2( 0.094184101, 0.92938870 ),
-        vec2( -0.34495938, -0.29387760 )
-    );
 
-    for(int i = 0; i < 8; i++){
+    Ray shRay = createRay(lighDir * (-1.0), ray.pos + (-0.5)*lighDir);
-        Ray shRay = Ray(lighDir * (-1.0) + vec3(offsets[i].x,.0,offsets[i].y)*0.05, ray.pos + 0.5*normal, .0,.0, vec3(.0));
     shRay = march(shRay);
-        if( (dot(lighDir,normal) < 0.0) && (shRay.len <20)){
-            shLeve -= 0.125*max(1.0-shRay.len*0.07 , 0.0);
-        }
-    }
 
-    light *= shLeve * .8;
+    if( dot(lighDir,normal) < 0. ){
+        if( shRay.len <80){
+            shLeve = .0;//shRay.len*0.02 , 0.0;
+        }
+        else {
+            shLeve = shRay.small.min / shRay.small.len;
+            shLeve *= 9.0;
+            //shLeve = pow(shLeve*10.0,0.5);
+        }
+    }
+    shLeve = min(max(shLeve, 0.0),1.0);
+
+    light *= shLeve;
 
     if(ray.min <= 0.2){
+        //FragColor = vec4(vec3(shRay.small.min)*0.1,1.0);
         FragColor = vec4(ray.color * (light+0.3), 1.0);
     } else {
         FragColor = vec4(.0,0.0,0.0,1.0);