Added basic raycaster demo. I have no idea why I did this.

examples/raycaster/raycaster.go

@@ -0,0 +1,153 @@
+package main
+
+import "math"
+import "image/color"
+import "git.tebibyte.media/sashakoshka/tomo/input"
+import "git.tebibyte.media/sashakoshka/tomo/config"
+import "git.tebibyte.media/sashakoshka/tomo/artist"
+import "git.tebibyte.media/sashakoshka/tomo/elements/core"
+
+type ControlState struct {
+	WalkForward  bool
+	WalkBackward bool
+	StrafeLeft   bool
+	StrafeRight  bool
+	LookLeft     bool
+	LookRight    bool
+}
+
+type Raycaster struct {
+	*core.Core
+	*core.FocusableCore
+	core core.CoreControl
+	focusableControl core.FocusableCoreControl
+	config config.Wrapped
+
+	Camera
+	controlState ControlState
+	world World
+	onControlStateChange func (ControlState)
+}
+
+func NewRaycaster (world World) (element *Raycaster) {
+	element = &Raycaster {
+		Camera: Camera {
+			X: 2,
+			Y: 2,
+			Angle: 1,
+			Fov:   1,
+		},
+		world: world,
+	}
+	element.Core, element.core = core.NewCore(element.drawAll)
+	element.FocusableCore,
+	element.focusableControl = core.NewFocusableCore(element.Draw)
+	element.core.SetMinimumSize(64, 64)
+	return
+}
+
+func (element *Raycaster) OnControlStateChange (callback func (ControlState)) {
+	element.onControlStateChange = callback
+}
+
+func (element *Raycaster) Draw () {
+	if element.core.HasImage() {
+		element.drawAll()
+		element.core.DamageAll()
+	}
+}
+
+func (element *Raycaster) HandleMouseDown (x, y int, button input.Button) {
+	if !element.Focused() { element.Focus() }
+}
+
+func (element *Raycaster) HandleMouseUp (x, y int, button input.Button) { }
+func (element *Raycaster) HandleMouseMove (x, y int) { }
+func (element *Raycaster) HandleMouseScroll (x, y int, deltaX, deltaY float64) { }
+
+func (element *Raycaster) HandleKeyDown (key input.Key, modifiers input.Modifiers) {
+	switch key {
+	case input.KeyLeft:  element.controlState.LookLeft  = true
+	case input.KeyRight: element.controlState.LookRight = true
+	case 'a', 'A': element.controlState.StrafeLeft   = true
+	case 'd', 'D': element.controlState.StrafeRight  = true
+	case 'w', 'W': element.controlState.WalkForward  = true
+	case 's', 'S': element.controlState.WalkBackward = true
+	default: return
+	}
+
+	if element.onControlStateChange != nil {
+		element.onControlStateChange(element.controlState)
+	}
+}
+
+func (element *Raycaster) HandleKeyUp(key input.Key, modifiers input.Modifiers) {
+	switch key {
+	case input.KeyLeft:  element.controlState.LookLeft  = false
+	case input.KeyRight: element.controlState.LookRight = false
+	case 'a', 'A': element.controlState.StrafeLeft   = false
+	case 'd', 'D': element.controlState.StrafeRight  = false
+	case 'w', 'W': element.controlState.WalkForward  = false
+	case 's', 'S': element.controlState.WalkBackward = false
+	default: return
+	}
+
+	if element.onControlStateChange != nil {
+		element.onControlStateChange(element.controlState)
+	}
+}
+
+func (element *Raycaster) drawAll () {
+	bounds := element.Bounds()
+	// artist.FillRectangle(element.core, artist.Uhex(0x000000FF), bounds)
+	width  := bounds.Dx()
+	height := bounds.Dy()
+
+	ray := Ray {
+		Angle: element.Camera.Angle - element.Camera.Fov / 2,
+		Precision: 64,
+	}
+	
+	for x := 0; x < width; x ++ {
+		ray.X = element.Camera.X
+		ray.Y = element.Camera.Y
+		
+		distance    := ray.Cast(element.world, 8)
+		distanceFac := float64(distance) / 8
+		distance    *= math.Cos(ray.Angle - element.Camera.Angle)
+		
+		wallHeight := height
+		if distance > 0 {
+			wallHeight = int((float64(height) / 2.0) / float64(distance))
+		}
+
+		ceilingColor := color.RGBA { 0x00, 0x00, 0x00, 0xFF }
+		wallColor    := color.RGBA { 0xCC, 0x33, 0x22, 0xFF }
+		floorColor   := color.RGBA { 0x11, 0x50, 0x22, 0xFF }
+
+		// fmt.Println(float64(distance) / 32)
+
+		wallColor  = artist.LerpRGBA(wallColor, ceilingColor, distanceFac)
+
+		// draw
+		data, stride := element.core.Buffer()
+		wallStart := height / 2 - wallHeight + bounds.Min.Y
+		wallEnd   := height / 2 + wallHeight + bounds.Min.Y
+		if wallStart < 0            { wallStart = 0 }
+		if wallEnd   > bounds.Max.Y { wallEnd   = bounds.Max.Y }
+		for y := bounds.Min.Y; y < wallStart; y ++ {
+			data[y * stride + x + bounds.Min.X] = ceilingColor
+		}
+		for y := wallStart; y < wallEnd; y ++ {
+			data[y * stride + x + bounds.Min.X] = wallColor
+		}
+		for y := wallEnd; y < bounds.Max.Y; y ++ {
+			floorFac := float64(y - (height / 2)) / float64(height / 2)
+			data[y * stride + x + bounds.Min.X] =
+				artist.LerpRGBA(ceilingColor, floorColor, floorFac)
+		}
+
+		// increment angle
+		ray.Angle += element.Camera.Fov / float64(width)
+	}
+}