Init, test raylib & math things

sdf.go

@@ -0,0 +1,67 @@
+package main
+
+const EPS = 0.001
+
+type SDF interface {
+	Distance(Vector3) float64
+}
+
+func Gradient(sdf SDF, p Vector3, eps float64) Vector3 {
+	dx := (sdf.Distance(p.Add(Vector3{X: eps})) - sdf.Distance(p.Add(Vector3{X: -eps}))) / (2 * eps)
+	dy := (sdf.Distance(p.Add(Vector3{Y: eps})) - sdf.Distance(p.Add(Vector3{Y: -eps}))) / (2 * eps)
+	dz := (sdf.Distance(p.Add(Vector3{Z: eps})) - sdf.Distance(p.Add(Vector3{Z: -eps}))) / (2 * eps)
+	return Vector3{X: dx, Y: dy, Z: dz}
+}
+
+// Some transformations see https://iquilezles.org/articles/distfunctions/
+
+type translatedSDF struct {
+	primitive SDF
+	translate Vector3
+}
+
+func (s translatedSDF) Distance(p Vector3) float64 {
+	return s.primitive.Distance(p.Sub(s.translate))
+}
+
+type rotatedSDF struct {
+	primitive SDF
+	rotVector Vector3
+	angle     float64
+}
+
+func (s rotatedSDF) Distance(p Vector3) float64 {
+	rotated_p := rotate(p, s.rotVector, s.angle)
+	return s.primitive.Distance(rotated_p)
+}
+
+type scaledSDF struct {
+	primitive SDF
+	scale     float64
+}
+
+func (s scaledSDF) Distance(p Vector3) float64 {
+	return s.primitive.Distance(p.Scale(1/s.scale)) * s.scale
+}
+
+type infiniteRep struct {
+	primitive SDF
+	cellSize  Vector3
+}
+
+// TODO
+// func (s infiniteRep) Distance(p Vector3) float64 {
+// 	x, y, z := p.Unpack()
+// 	sx, sy, sz := s.cellSize.Unpack()
+// }
+
+// Sphere
+
+type Sphere struct {
+	center Vector3
+	radius float64
+}
+
+func (s Sphere) Distance(p Vector3) float64 {
+	return p.Sub(s.center).Length()
+}