shadows

src/ray_marching.go

@@ -17,8 +17,10 @@ const WIDTH = 500
 const HEIGHT = 500
 const PI = math.Pi
 
+const SOFT_SHADOW_COEFF = 4
+
 var lightPos Vector3
-var scene SmoothUnionSDF
+var scene SDF
 
 // radius, theta, phi
 var screenSpherical Vector3
@@ -28,16 +30,17 @@ var cameraPos Vector3
 func init() {
 	lightPos = Vector3{0, -200, 800}
 
-	cameraPos = Vector3{0, -10, 30}
+	cameraPos = Vector3{0, -10, 25}
 	screenSpherical = Vector3{10, PI/2 + 0.2, PI / 2}
 	screenPhysicalSize = 5
 
 	sphereMat := RED_MAT
 	sphereMat.specularFac = 0.5
-	sphere := TranslatedSDF{Sphere{10, sphereMat}, Vector3{0, 100, 5}}
+	sphere := TranslatedSDF{Sphere{10, sphereMat}, Vector3{0, 100, 15}}
+	// sphere := RepeatSDF{Sphere{20, sphereMat}, Vector3{50, 50, 50}}
 	plane := Plane{Vector3{0, 0, 1}, WHITE_GREY_GRID_MAT}
 
-	scene = SmoothUnionSDF{sphere, plane, 2}
+	scene = UnionSDF{sphere, plane}
 
 }
 
@@ -56,13 +59,33 @@ func phongShading(point Vector3, normal Vector3, mat Material) Vector3 {
 	return ambiant.Add(diffuse).Add(specular)
 }
 
+func shadow(point Vector3) float64 {
+	direction := (lightPos.Sub(point)).Normalized()
+	p := point.Add(direction.Scale(5 * EPS))
+	res := 1.0
+	dist_total := 0.0
+	for range MAX_STEP {
+		dist, _ := scene.Distance(p)
+		if dist < EPS {
+			return 0.1
+		}
+		if dist > MAX_DIST {
+			break
+		}
+		res = min(res, SOFT_SHADOW_COEFF*dist/dist_total)
+		dist_total += dist
+		p = p.Add(direction.Scale(dist))
+	}
+	return res
+}
+
 func rayMarch(origin Vector3, direction Vector3) (bool, Vector3) {
 	p := origin
 	for range MAX_STEP {
 		dist, mat := scene.Distance(p)
 		if dist < EPS {
 			normal := Gradient(scene, p, EPS).Normalized()
-			return true, phongShading(p, normal, mat)
+			return true, phongShading(p, normal, mat).Scale(shadow(p))
 		}
 		if dist > MAX_DIST {
 			break