91 lines
1.9 KiB
Go
91 lines
1.9 KiB
Go
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package main
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import "math"
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import "image"
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type World interface {
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At (image.Point) int
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}
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type DefaultWorld struct {
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Data []int
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Stride int
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}
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func (world DefaultWorld) At (position image.Point) int {
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if position.X < 0 { return 0 }
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if position.Y < 0 { return 0 }
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if position.X >= world.Stride { return 0 }
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index := position.X + position.Y * world.Stride
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if index >= len(world.Data) { return 0 }
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return world.Data[index]
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}
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type Camera struct {
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X, Y float64
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Angle float64
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Fov float64
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}
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func (camera *Camera) Point () (image.Point) {
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return image.Pt(int(camera.X), int(camera.Y))
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}
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func (camera *Camera) Rotate (by float64) {
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camera.Angle += by
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if camera.Angle < 0 { camera.Angle += math.Pi * 2 }
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if camera.Angle > math.Pi * 2 { camera.Angle = 0 }
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}
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func (camera *Camera) Walk (by float64) {
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dx, dy := camera.Delta()
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camera.X += dx * by
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camera.Y += dy * by
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}
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func (camera *Camera) Strafe (by float64) {
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dx, dy := camera.OffsetDelta()
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camera.X += dx * by
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camera.Y += dy * by
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}
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func (camera *Camera) Delta () (x float64, y float64) {
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return math.Cos(camera.Angle), math.Sin(camera.Angle)
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}
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func (camera *Camera) OffsetDelta () (x float64, y float64) {
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offset := math.Pi / 2
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return math.Cos(camera.Angle + offset), math.Sin(camera.Angle + offset)
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}
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type Ray struct {
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X, Y float64
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Angle float64
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Precision int
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}
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func (ray *Ray) Cast (world World, max int) (distance float64) {
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precision := 64
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dX := math.Cos(ray.Angle) / float64(precision)
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dY := math.Sin(ray.Angle) / float64(precision)
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origX, origY := ray.X, ray.Y
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wall := 0
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depth := 0
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for wall == 0 && depth < max * precision {
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ray.X += dX
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ray.Y += dY
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wall = world.At(ray.Point())
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depth ++
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}
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distanceX := origX - ray.X
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distanceY := origY - ray.Y
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return math.Sqrt(distanceX * distanceX + distanceY * distanceY)
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}
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func (ray *Ray) Point () (image.Point) {
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return image.Pt(int(ray.X), int(ray.Y))
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}
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