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import kotlin.js.Date
import kotlin.math.pow
class Raycaster(private val stepPrecision: Int) {
fun raycast(raycastContext: RaycastContext) {
val raycastStartMs = Date().getTime()
val (renderer, textureManager, camera, map, _) = raycastContext
val viewportWidth = renderer.viewportWidth
val viewportHeight = renderer.viewportHeight
val viewportHeightHalf = viewportHeight / 2
var raySweepAngle = camera.rotation - (camera.fov / 2)
for (rayIndex in 0 until viewportWidth) {
var rayX = camera.xPos
var rayY = camera.yPos
var objectTypeHit: Int
do {
rayX += raySweepAngle.cosine() / stepPrecision
rayY += raySweepAngle.sine() / stepPrecision
// TODO bounds checking
objectTypeHit = map.data[rayY.toFlooredInt()][rayX.toFlooredInt()]
} while (objectTypeHit == 0)
val texture = textureManager.getTexture(objectTypeHit)
val textureXIndex = ((texture.width * (rayX + rayY)) % texture.width).toFlooredInt()
val distanceToWall = kotlin.math.sqrt((camera.xPos - rayX).pow(2) + (camera.yPos - rayY).pow(2))
val wallHeight = viewportHeightHalf / distanceToWall
// Ceiling
renderer.drawLine(rayIndex, 0.0, rayIndex, viewportHeightHalf - wallHeight, "#505050")
// Wall
drawWallTexture(rayIndex, wallHeight, textureXIndex, texture, renderer)
// Floor
renderer.drawLine(rayIndex, viewportHeightHalf + wallHeight, rayIndex, viewportHeight, "#A9A9A9")
raySweepAngle += (camera.fov / viewportWidth.toDouble())
}
console.log("Viewport raycast in ${Date().getTime() - raycastStartMs}ms")
}
private fun drawWallTexture(rayIndex: Int, wallHeight: Double, textureXIndex: Int, texture: Texture, renderer: Renderer) {
val yIncrement = (wallHeight * 2) / texture.height
var y = (renderer.viewportHeight/2) - wallHeight
for (i in 0 until texture.height) {
// Extend y length by 0.1 to overlap strips slightly to avoid screen-door like effect
renderer.drawLine(rayIndex, y, rayIndex, y + yIncrement + 0.1, texture.cssColourPixelList[textureXIndex + i * texture.width])
y += yIncrement
}
}
}
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