Resolving player stucj problem

coll_updated.go

package collision

import (
	rl "github.com/gen2brain/raylib-go/raylib"
)

type Line struct {
	Start rl.Vector2
	End   rl.Vector2
}

func rectToLines(rect rl.Rectangle) [4]Line {
	return [4]Line{
		{Start: rl.Vector2{X: rect.X, Y: rect.Y + rect.Height}, End: rl.Vector2{X: rect.X, Y: rect.Y}},                           // left
		{Start: rl.Vector2{X: rect.X + rect.Width, Y: rect.Y}, End: rl.Vector2{X: rect.X + rect.Width, Y: rect.Y + rect.Height}}, // right

		{Start: rl.Vector2{X: rect.X, Y: rect.Y}, End: rl.Vector2{X: rect.X + rect.Width, Y: rect.Y}},                             // top
		{Start: rl.Vector2{X: rect.X + rect.Width, Y: rect.Y + rect.Height}, End: rl.Vector2{X: rect.X, Y: rect.Y + rect.Height}}, // bottom
	}
}

func MoveCollide(rect rl.Rectangle, newPos rl.Vector2, otherRect rl.Rectangle) rl.Rectangle {
	if rect.X == newPos.X && rect.Y == newPos.Y {
		return rect
	}

	otherRect.Width += rect.Width
	otherRect.Height += rect.Height
	otherRect.X -= rect.Width
	otherRect.Y -= rect.Height

	rectPos := rl.Vector2{rect.X, rect.Y}
	movLine := Line{Start: rectPos, End: newPos}
	resolvedPos := newPos

	minIntersectionPoint := rl.Vector2{}
	collidedFace := -1
	collided := false
	for i, line := range rectToLines(otherRect) {
		intersection, intersects := lineIntersect(line, movLine)
		if intersects {
			if collided {
				if rl.Vector2DistanceSqr(intersection, rectPos) < rl.Vector2DistanceSqr(minIntersectionPoint, rectPos) {
					minIntersectionPoint = intersection
					collidedFace = i
				}
			} else {
				minIntersectionPoint = intersection
				collidedFace = i
				collided = true
			}
		}
	}

	if !collided {
		rect.X = newPos.X
		rect.Y = newPos.Y
		return rect
	}

	switch collidedFace {
	case 0: // left
		if newPos.X >= minIntersectionPoint.X {
			resolvedPos.X = minIntersectionPoint.X
		}
	case 1: // right
		if newPos.X <= minIntersectionPoint.X {
			resolvedPos.X = minIntersectionPoint.X
		}
	case 2: // top
		if newPos.Y >= minIntersectionPoint.Y {
			resolvedPos.Y = minIntersectionPoint.Y
		}
	case 3: // bottom
		if newPos.Y <= minIntersectionPoint.Y {
			resolvedPos.Y = minIntersectionPoint.Y
		}
	}

	rect.X = resolvedPos.X
	rect.Y = resolvedPos.Y

	return rect
}

func lineIntersect(l1, l2 Line) (rl.Vector2, bool) {
	det := (l1.End.X-l1.Start.X)*(l2.End.Y-l2.Start.Y) - (l1.End.Y-l1.Start.Y)*(l2.End.X-l2.Start.X)

	if det == 0 {
		return rl.Vector2{}, false
	}

	t := ((l2.Start.X-l1.Start.X)*(l2.End.Y-l2.Start.Y) - (l2.Start.Y-l1.Start.Y)*(l2.End.X-l2.Start.X)) / det
	u := -((l1.Start.X-l1.End.X)*(l1.Start.Y-l2.Start.Y) - (l1.Start.Y-l1.End.Y)*(l1.Start.X-l2.Start.X)) / det

	if t >= 0 && t <= 1 && u >= 0 && u <= 1 {
		// Intersection point
		intersectionX := l1.Start.X + t*(l1.End.X-l1.Start.X)
		intersectionY := l1.Start.Y + t*(l1.End.Y-l1.Start.Y)
		return rl.Vector2{intersectionX, intersectionY}, true
	}

	// Lines do not intersect within the given segments
	return rl.Vector2{}, false
}