so sloooow
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@ -56,9 +56,9 @@ func main() {
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//halfwidth := float32(fb.Width / 2)
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//halfheight := float32(fb.Height / 2)
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for range Repeat {
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Triangle1(&fb, 0xFF0000, Vec2i{10, 70}, Vec2i{50, 160}, Vec2i{70, 80})
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Triangle1(&fb, 0xFFFFFF, Vec2i{180, 50}, Vec2i{150, 1}, Vec2i{70, 180})
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Triangle1(&fb, 0x00FF00, Vec2i{180, 150}, Vec2i{120, 160}, Vec2i{130, 180})
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Triangle2(&fb, 0xFF0000, Vec2i{10, 70}, Vec2i{50, 160}, Vec2i{70, 80})
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Triangle2(&fb, 0xFFFFFF, Vec2i{180, 50}, Vec2i{150, 1}, Vec2i{70, 180})
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Triangle2(&fb, 0x00FF00, Vec2i{180, 150}, Vec2i{120, 160}, Vec2i{130, 180})
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}
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/*
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@ -17,6 +17,10 @@ type Vec2i struct {
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X, Y int
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}
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type Vec2f struct {
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X, Y float32
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}
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type Facef [3]Vec3f
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type ObjModel struct {
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@ -24,6 +28,14 @@ type ObjModel struct {
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Faces []Facef
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}
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func (vi *Vec2i) ToF() Vec2f {
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return Vec2f{float32(vi.X), float32(vi.Y)}
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}
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// func CrossProduct(v0, v1 Vec3f) Vec3f {
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//
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// }
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// Parse an obj file at the given reader. Only handles v and f right now
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func ParseObj(reader io.Reader) (*ObjModel, error) {
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result := ObjModel{
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@ -1,6 +1,7 @@
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package main
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import (
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//"log"
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"math"
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)
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@ -98,3 +99,80 @@ func Triangle1(fb *Framebuffer, color uint, v0 Vec2i, v1 Vec2i, v2 Vec2i) {
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}
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}
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}
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// How does this work? Compare with your
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// other barycentric function (in a different repo). In the original
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// cpp code, they used an overloaded operator ^ to mean cross product
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func Barycentric(v0, v1, v2, p Vec2i) Vec3f {
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// WARN: Just not doing this one
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u := Vec3f{}
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if math.Abs(float64(u.Z)) < 1 {
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return Vec3f{-1, 1, 1}
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}
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return Vec3f{1 - (u.X+u.Y)/u.Z, u.Y / u.Z, u.X / u.Z}
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}
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// Figure out the minimum bounding box for a triangle defined by
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// these vertices. Returns the top left and bottom right points,
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// inclusive
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func ComputeBoundingBox(v0, v1, v2 Vec2i) (Vec2i, Vec2i) {
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return Vec2i{min(v0.X, v1.X, v2.X), min(v0.Y, v1.Y, v2.Y)},
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Vec2i{max(v0.X, v1.X, v2.X), max(v0.Y, v1.Y, v2.Y)}
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}
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// The generic edge function, returning positive if P is on the right side of
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// the line drawn between v1 and v2. This is counter clockwise
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func EdgeFunction(v1, v2, p Vec2f) float32 {
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return (p.X-v1.X)*(v2.Y-v1.Y) - (p.Y-v1.Y)*(v2.X-v1.X)
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}
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// This computes the x and y per-pixel increment for the line going
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// between v1 and v2 (also counter clockwise)
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func EdgeIncrement(v1, v2 Vec2f) (float32, float32) {
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return (v2.Y - v1.Y), -(v2.X - v1.X)
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}
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func Triangle2(fb *Framebuffer, color uint, v0 Vec2i, v1 Vec2i, v2 Vec2i) {
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boundsTL, boundsBR := ComputeBoundingBox(v0, v1, v2)
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const expand = (2 << 12)
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//log.Print(boundsTL, boundsBR)
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v0f := v0.ToF()
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v1f := v1.ToF()
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v2f := v2.ToF()
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// Where to start our scanning
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pstart := Vec2f{float32(boundsTL.X) + 0.5, float32(boundsTL.Y) + 0.5}
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// parea := EdgeFunction(v0f, v1f, v2f)
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// invarea := 1 / parea
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w0_y := int(expand * EdgeFunction(v1f, v2f, pstart))
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w1_y := int(expand * EdgeFunction(v2f, v0f, pstart))
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w2_y := int(expand * EdgeFunction(v0f, v1f, pstart))
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w0_xit, w0_yit := EdgeIncrement(v1f, v2f)
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w1_xit, w1_yit := EdgeIncrement(v2f, v0f)
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w2_xit, w2_yit := EdgeIncrement(v0f, v1f)
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w0_xi := int(expand * w0_xit)
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w0_yi := int(expand * w0_yit)
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w1_xi := int(expand * w1_xit)
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w1_yi := int(expand * w1_yit)
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w2_xi := int(expand * w2_xit)
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w2_yi := int(expand * w2_yit)
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for y := boundsTL.Y; y <= boundsBR.Y; y++ {
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w0 := w0_y
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w1 := w1_y
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w2 := w2_y
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for x := boundsTL.X; x <= boundsBR.X; x++ {
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if w0 >= 0 && w1 >= 0 && w2 >= 0 {
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fb.SetSafe(uint(x), uint(y), color)
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// w0a := w0 * invarea
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// w1a := w1 * invarea
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// w2a := w2 * invarea
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}
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w0 += w0_xi
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w1 += w1_xi
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w2 += w2_xi
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}
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w0_y += w0_yi
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w1_y += w1_yi
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w2_y += w2_yi
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}
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}
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