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December 12, 2012 12:28
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This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -244,7 +244,6 @@ func render(img []uint8, w int, h int, nsubsamples int) { isect.rayPlaneIntersect(ray, plane) if isect.hit > 0 { col := ambientOcclusion(isect) fimg[3*(y*w+x)+0] += col.x -
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Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -0,0 +1,319 @@ package main import ( "image" "image/color" "image/png" "math" "math/rand" "os" ) const ( WIDTH = 256 HEIGHT = 256 NSUBSAMPLES = 2 NAO_SAMPLES = 8 ) type Vec struct { x float64 y float64 z float64 } type Isect struct { t float64 p Vec n Vec hit int } type Sphere struct { center Vec radius float64 } type Plane struct { p Vec n Vec } type Ray struct { org Vec dir Vec } var spheres [3]Sphere var plane Plane func dot(v0 Vec, v1 Vec) float64 { return v0.x*v1.x + v0.y*v1.y + v0.z*v1.z } func cross(v0 Vec, v1 Vec) (c Vec) { c.x = v0.y*v1.z - v0.z*v1.y c.y = v0.z*v1.x - v0.x*v1.z c.z = v0.x*v1.y - v0.y*v1.x return c } func normalize(v Vec) (c Vec) { c = v length := math.Sqrt(dot(c, c)) if math.Abs(length) > 1.0e-17 { c.x /= length c.y /= length c.z /= length } return c } func (isect *Isect) raySphereIntersect(ray Ray, sphere Sphere) { var rs Vec rs.x = ray.org.x - sphere.center.x rs.y = ray.org.y - sphere.center.y rs.z = ray.org.z - sphere.center.z B := dot(rs, ray.dir) C := dot(rs, rs) - sphere.radius*sphere.radius D := B*B - C if D > 0.0 { t := -B - math.Sqrt(D) if (t > 0.0) && (t < isect.t) { isect.t = t isect.hit = 1 isect.p.x = ray.org.x + ray.dir.x*t isect.p.y = ray.org.y + ray.dir.y*t isect.p.z = ray.org.z + ray.dir.z*t isect.n.x = isect.p.x - sphere.center.x isect.n.y = isect.p.y - sphere.center.y isect.n.z = isect.p.z - sphere.center.z isect.n = normalize(isect.n) } } } func (isect *Isect) rayPlaneIntersect(ray Ray, plane Plane) { d := -dot(plane.p, plane.n) v := dot(ray.dir, plane.n) if math.Abs(v) < 1.0e-17 { return } t := -(dot(ray.org, plane.n) + d) / v if (t > 0.0) && (t < isect.t) { isect.t = t isect.hit = 1 isect.p.x = ray.org.x + ray.dir.x*t isect.p.y = ray.org.y + ray.dir.y*t isect.p.z = ray.org.z + ray.dir.z*t isect.n = plane.n } } func orthoBasis(n Vec) (basis [3]Vec) { basis[2] = n basis[1].x = 0.0 basis[1].y = 0.0 basis[1].z = 0.0 if (n.x < 0.6) && (n.x > -0.6) { basis[1].x = 1.0 } else if (n.y < 0.6) && (n.y > -0.6) { basis[1].y = 1.0 } else if (n.z < 0.6) && (n.z > -0.6) { basis[1].z = 1.0 } else { basis[1].x = 1.0 } basis[0] = cross(basis[1], basis[2]) basis[0] = normalize(basis[0]) basis[1] = cross(basis[2], basis[0]) basis[1] = normalize(basis[1]) return basis } func ambientOcclusion(isect Isect) (col Vec) { ntheta := NAO_SAMPLES nphi := NAO_SAMPLES eps := 0.0001 var p Vec p.x = isect.p.x + eps*isect.n.x p.y = isect.p.y + eps*isect.n.y p.z = isect.p.z + eps*isect.n.z basis := orthoBasis(isect.n) occlusion := 0.0 for j := 0; j < ntheta; j++ { for i := 0; i < nphi; i++ { theta := math.Sqrt(rand.Float64()) phi := 2.0 * math.Pi * rand.Float64() x := math.Cos(phi) * theta y := math.Sin(phi) * theta z := math.Sqrt(1.0 - theta*theta) rx := x*basis[0].x + y*basis[1].x + z*basis[2].x ry := x*basis[0].y + y*basis[1].y + z*basis[2].y rz := x*basis[0].z + y*basis[1].z + z*basis[2].z var ray Ray ray.org = p ray.dir.x = rx ray.dir.y = ry ray.dir.z = rz var occIsect Isect occIsect.t = 1.0e+17 occIsect.hit = 0 occIsect.raySphereIntersect(ray, spheres[0]) occIsect.raySphereIntersect(ray, spheres[1]) occIsect.raySphereIntersect(ray, spheres[2]) occIsect.rayPlaneIntersect(ray, plane) if occIsect.hit > 0.0 { occlusion += 1.0 } } } occlusion = (float64(ntheta)*float64(nphi) - occlusion) / float64(ntheta*nphi) col.x = occlusion col.y = occlusion col.z = occlusion return col } func clamp(f float64) uint8 { i := int(f * 255) if i < 0 { i = 0 } if i > 255 { i = 255 } return uint8(i) } func render(img []uint8, w int, h int, nsubsamples int) { fimg := make([]float64, w*h*3) for y := 0; y < h; y++ { for x := 0; x < w; x++ { for v := 0; v < nsubsamples; v++ { for u := 0; u < nsubsamples; u++ { px := (float64(x) + (float64(u) / float64(nsubsamples)) - (float64(w) / 2.0)) / (float64(w) / 2.0) py := -(float64(y) + (float64(v) / float64(nsubsamples)) - (float64(h) / 2.0)) / (float64(h) / 2.0) var ray Ray ray.dir.x = px ray.dir.y = py ray.dir.z = -1.0 ray.dir = normalize(ray.dir) var isect Isect isect.t = 1.0e+17 isect.hit = 0 isect.raySphereIntersect(ray, spheres[0]) isect.raySphereIntersect(ray, spheres[1]) isect.raySphereIntersect(ray, spheres[2]) isect.rayPlaneIntersect(ray, plane) if isect.hit > 0 { // col := ambientOcclusion(isect) fimg[3*(y*w+x)+0] += col.x fimg[3*(y*w+x)+1] += col.y fimg[3*(y*w+x)+2] += col.z } } } fimg[3*(y*w+x)+0] /= float64(nsubsamples * nsubsamples) fimg[3*(y*w+x)+1] /= float64(nsubsamples * nsubsamples) fimg[3*(y*w+x)+2] /= float64(nsubsamples * nsubsamples) img[3*(y*w+x)+0] = clamp(fimg[3*(y*w+x)+0]) img[3*(y*w+x)+1] = clamp(fimg[3*(y*w+x)+1]) img[3*(y*w+x)+2] = clamp(fimg[3*(y*w+x)+2]) } } } func savePng(fname string, w int, h int, img []uint8) { i := image.NewRGBA(image.Rect(0, 0, w, h)) for y := 0; y < h; y++ { for x := 0; x < w; x++ { r := img[3*(y*w+x)+0] g := img[3*(y*w+x)+1] b := img[3*(y*w+x)+2] i.Set(x, y, color.RGBA{r, g, b, 255}) } } f, e := os.OpenFile(fname, os.O_CREATE|os.O_WRONLY, 0666) if e != nil { panic(e) } defer f.Close() png.Encode(f, i) } func initScene() { spheres[0].center.x = -2.0 spheres[0].center.y = 0.0 spheres[0].center.z = -3.5 spheres[0].radius = 0.5 spheres[1].center.x = -0.5 spheres[1].center.y = 0.0 spheres[1].center.z = -3.0 spheres[1].radius = 0.5 spheres[2].center.x = 1.0 spheres[2].center.y = 0.0 spheres[2].center.z = -2.2 spheres[2].radius = 0.5 plane.p.x = 0.0 plane.p.y = -0.5 plane.p.z = 0.0 plane.n.x = 0.0 plane.n.y = 1.0 plane.n.z = 0.0 } func main() { img := make([]uint8, WIDTH*HEIGHT*3) initScene() render(img, WIDTH, HEIGHT, NSUBSAMPLES) savePng("ao.png", WIDTH, HEIGHT, img) }