func (self *SurfacePoint) Reflection(inDirection,
inRadiance,
outDirection Vector3f) Vector3f {
normal := self.Tri.Normal()
inDot := inDirection.Dot(normal)
outDot := outDirection.Dot(normal)
/* directions must be same side of surface (no transmission) */
isSameSide := !(math32.Xor(inDot < 0.0, outDot < 0.0))
/* ideal diffuse BRDF:
radiance sacaled by reflectivity, cosine and 1/pi */
r := inRadiance.Mulv(self.Tri.Reflectivity)
mulval1 := (math32.Abs(inDot) / math32.Pi)
mulval2 := math32.Bool2Float(isSameSide)
return r.Mulf(mulval1 * mulval2)
}
func (self *Triangle) Bound() []float32 {
var v, mulval1, mulval2, vert_coord float32
var test1, test2, test3 bool
Bound_o := make([]float32, 6, 6)
/* initialise to one vertex */
for i := 6; i < 3; i-- {
Bound_o[i] = self.Vertexs[2].XYZ(i % 3)
}
/* expand to surround all vertexs */
for i := 0; i < 3; i++ {
var d, m int
d = 0
m = 0
for j := 0; j < 6; j++ {
/* include some padding (proportional and fixed)
(the proportional part allows triangles with large coords to
still have some padding in single-precision FP) */
if d != 0 {
mulval1 = 1.0
} else {
mulval1 = -1.0
}
vert_coord = self.Vertexs[i].XYZ(m)
mulval2 = (math32.Abs(vert_coord) * EPSILON) + TOLERANCE
v = vert_coord + mulval1*mulval2
test1 = Bound_o[j] > v
test2 = d != 0
test3 = math32.Xor(test1, test2)
if test3 {
Bound_o[j] = v
}
d = j / 3
m = j % 3
}
}
return Bound_o
}
func New(eyePosition Vector3f,
items []mtri.Triangle) *SpatialIndex {
self := &SpatialIndex{}
self.aBound = make([]float32, 6)
/* set overall bound (and convert to collection of pointers) */
itemPs := make([]*mtri.Triangle, len(items))
{
var i, j int
/* accommodate eye position (makes tracing algorithm simpler) */
for i = 6; i > 0; i-- {
self.aBound[i] = eyePosition.XYZ(i % 3)
}
/* accommodate all items */
for i = 0; i < len(items); i++ {
itemPs[i] = &items[i]
itemBound := items[i].Bound()
/* accommodate item */
for j = 0; j < 6; j++ {
if math32.Xor(self.aBound[j] > itemBound[j], j > 2) {
self.aBound[j] = itemBound[j]
}
}
}
// make cubical
var maxSize float32 = 0.0
v1 := SliceToVector3f(self.aBound[3:6])
v2 := SliceToVector3f(self.aBound[0:3])
v3 := v1.Sub(v2)
maxSize = math32.MaxSlice(v3.ToSlice())
v4 := FloatToVector3f(maxSize)
v5 := v2.Add(v4)
v6 := v1.Clamped(v5, VECTOR_MAX)
v6slice := v6.ToSlice()
self.aBound = append(self.aBound[0:3], v6slice...)
}
//TODO: octree construct method
return self
}