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examples/raycasting: Refactoring

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This commit is contained in:
Hajime Hoshi 2019-02-18 01:26:31 +09:00
parent d724e17032
commit 6906ea1c4f
1 changed files with 64 additions and 60 deletions
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124
examples/raycasting/main.go
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@ -36,6 +36,7 @@ import (
const (
screenWidth = 240
screenHeight = 240
padding = 20
)
var (
@ -64,16 +65,31 @@ func init() {
triangleImage.Fill(color.White)
}
type Line struct {
type line struct {
X1, Y1, X2, Y2 float64
}
func (l *Line) angle() float64 {
func (l *line) angle() float64 {
return math.Atan2(l.Y2-l.Y1, l.X2-l.X1)
}
func newRay(x, y, length, angle float64) Line {
return Line{
type object struct {
walls []line
}
func (o object) points() [][2]float64 {
// Get one of the endpoints for all segments,
// + the startpoint of the first one, for non-closed paths
var points [][2]float64
for _, wall := range o.walls {
points = append(points, [2]float64{wall.X2, wall.Y2})
}
points = append(points, [2]float64{o.walls[0].X1, o.walls[0].Y1})
return points
}
func newRay(x, y, length, angle float64) line {
return line{
X1: x,
Y1: y,
X2: x + length*math.Cos(angle),
@ -82,49 +98,40 @@ func newRay(x, y, length, angle float64) Line {
}
// intersection calculates the intersection of given two lines.
func intersection(l1, l2 Line) (float64, float64, error) {
func intersection(l1, l2 line) (float64, float64, bool) {
// https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection#Given_two_points_on_each_line
denom := (l1.X1-l1.X2)*(l2.Y1-l2.Y2) - (l1.Y1-l1.Y2)*(l2.X1-l2.X2)
tNum := (l1.X1-l2.X1)*(l2.Y1-l2.Y2) - (l1.Y1-l2.Y1)*(l2.X1-l2.X2)
uNum := -((l1.X1-l1.X2)*(l1.Y1-l2.Y1) - (l1.Y1-l1.Y2)*(l1.X1-l2.X1))
if denom == 0 {
return 0, 0, errors.New("lines parallel or coincident")
return 0, 0, false
}
t := tNum / denom
if t > 1 || t < 0 {
return 0, 0, errors.New("lines intersect, segments do not")
return 0, 0, false
}
u := uNum / denom
if u > 1 || u < 0 {
return 0, 0, errors.New("lines intersect, segments do not")
return 0, 0, false
}
x := l1.X1 + t*(l1.X2-l1.X1)
y := l1.Y1 + t*(l1.Y2-l1.Y1)
return x, y, nil
return x, y, true
}
// rayCasting returns a slice of Line originating from point cx, cy and intersecting with objects
func rayCasting(cx, cy float64, objects [][]Line) []Line {
var rays []Line
// rayCasting returns a slice of line originating from point cx, cy and intersecting with objects
func rayCasting(cx, cy float64, objects []object) []line {
const rayLength = 1000 // something large enough to reach all objects
var rays []line
for _, obj := range objects {
// Get one of the endpoints for all segments,
// + the startpoint of the first one, for non-closed paths
var objPoints [][2]float64
for _, wall := range obj {
objPoints = append(objPoints, [2]float64{wall.X2, wall.Y2})
}
objPoints = append(objPoints, [2]float64{obj[0].X1, obj[0].Y1})
// Cast two rays per point
for _, p := range objPoints {
l := Line{cx, cy, p[0], p[1]}
for _, p := range obj.points() {
l := line{cx, cy, p[0], p[1]}
angle := l.angle()
for _, offset := range []float64{-0.005, 0.005} {
@ -133,8 +140,8 @@ func rayCasting(cx, cy float64, objects [][]Line) []Line {
// Unpack all objects
for _, o := range objects {
for _, wall := range o {
if px, py, err := intersection(ray, wall); err == nil {
for _, wall := range o.walls {
if px, py, ok := intersection(ray, wall); ok {
points = append(points, [2]float64{px, py})
}
}
@ -142,7 +149,7 @@ func rayCasting(cx, cy float64, objects [][]Line) []Line {
// Find the point closest to start of ray
min := math.Inf(1)
var minI = -1
minI := -1
for i, p := range points {
d2 := (cx-p[0])*(cx-p[0]) + (cy-p[1])*(cy-p[1])
if d2 < min {
@ -150,7 +157,7 @@ func rayCasting(cx, cy float64, objects [][]Line) []Line {
minI = i
}
}
rays = append(rays, Line{cx, cy, points[minI][0], points[minI][1]})
rays = append(rays, line{cx, cy, points[minI][0], points[minI][1]})
}
}
}
@ -162,23 +169,6 @@ func rayCasting(cx, cy float64, objects [][]Line) []Line {
return rays
}
func vertices(x1, y1, x2, y2, x3, y3 float64) []ebiten.Vertex {
return []ebiten.Vertex{
{float32(x1), float32(y1), 0, 0, 1, 1, 1, 1},
{float32(x2), float32(y2), 0, 0, 1, 1, 1, 1},
{float32(x3), float32(y3), 0, 0, 1, 1, 1, 1},
}
}
func rect(x, y, w, h float64) []Line {
return []Line{
{x, y, x, y + h},
{x, y + h, x + w, y + h},
{x + w, y + h, x + w, y},
{x + w, y, x, y},
}
}
func handleMovement() {
if ebiten.IsKeyPressed(ebiten.KeyD) || ebiten.IsKeyPressed(ebiten.KeyRight) {
px += 4
@ -214,6 +204,14 @@ func handleMovement() {
}
}
func rayVertices(x1, y1, x2, y2, x3, y3 float64) []ebiten.Vertex {
return []ebiten.Vertex{
{float32(x1), float32(y1), 0, 0, 1, 1, 1, 1},
{float32(x2), float32(y2), 0, 0, 1, 1, 1, 1},
{float32(x3), float32(y3), 0, 0, 1, 1, 1, 1},
}
}
func update(screen *ebiten.Image) error {
if inpututil.IsKeyJustPressed(ebiten.KeyEscape) {
return errors.New("game ended by player")
@ -231,23 +229,22 @@ func update(screen *ebiten.Image) error {
// Reset the shadowImage
shadowImage.Fill(color.Black)
rays := rayCasting(px, py, objects)
rays := rayCasting(float64(px), float64(py), objects)
// Subtract ray triangles from shadow
opt := &ebiten.DrawTrianglesOptions{}
opt.Address = ebiten.AddressRepeat
opt.CompositeMode = ebiten.CompositeModeSourceOut
for i, line := range rays {
nextLine := rays[(i+1)%len(rays)]
// Draw triangle of area between rays
v := vertices(px, py, nextLine.X2, nextLine.Y2, line.X2, line.Y2)
v := rayVertices(float64(px), float64(py), nextLine.X2, nextLine.Y2, line.X2, line.Y2)
shadowImage.DrawTriangles(v, []uint16{0, 1, 2}, triangleImage, opt)
}
// Draw background
screen.DrawImage(bgImage, &ebiten.DrawImageOptions{})
screen.DrawImage(bgImage, nil)
if showRays {
// Draw rays
@ -262,15 +259,15 @@ func update(screen *ebiten.Image) error {
screen.DrawImage(shadowImage, op)
// Draw walls
for _, wall := range objects {
for _, w := range wall {
for _, obj := range objects {
for _, w := range obj.walls {
ebitenutil.DrawLine(screen, w.X1, w.Y1, w.X2, w.Y2, color.RGBA{255, 0, 0, 255})
}
}
// Draw player as a rect
ebitenutil.DrawRect(screen, px-2, py-2, 4, 4, color.Black)
ebitenutil.DrawRect(screen, px-1, py-1, 2, 2, color.RGBA{255, 100, 100, 255})
ebitenutil.DrawRect(screen, float64(px)-2, float64(py)-2, 4, 4, color.Black)
ebitenutil.DrawRect(screen, float64(px)-1, float64(py)-1, 2, 2, color.RGBA{255, 100, 100, 255})
if showRays {
ebitenutil.DebugPrintAt(screen, "R: hide rays", padding, 0)
@ -285,25 +282,32 @@ func update(screen *ebiten.Image) error {
var (
showRays bool
px, py float64
objects [][]Line
px, py int
objects []object
)
const padding = 20
func rect(x, y, w, h float64) []line {
return []line{
{x, y, x, y + h},
{x, y + h, x + w, y + h},
{x + w, y + h, x + w, y},
{x + w, y, x, y},
}
}
func main() {
px = screenWidth / 2
py = screenHeight / 2
// Add outer walls
objects = append(objects, rect(padding, padding, screenWidth-2*padding, screenHeight-2*padding))
objects = append(objects, object{rect(padding, padding, screenWidth-2*padding, screenHeight-2*padding)})
// Angled wall
objects = append(objects, []Line{{50, 110, 100, 150}})
objects = append(objects, object{[]line{{50, 110, 100, 150}}})
// Rectangles
objects = append(objects, rect(45, 50, 70, 20))
objects = append(objects, rect(150, 50, 30, 60))
objects = append(objects, object{rect(45, 50, 70, 20)})
objects = append(objects, object{rect(150, 50, 30, 60)})
if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Ray casting and shadows (Ebiten demo)"); err != nil {
log.Fatal(err)