gl01/internal/world/viewray.go

package world

import (
	"edgaru089.ml/go/gl01/internal/util/itype"
)

func (w *World) castworker(from, dir itype.Vec3d, maxlen float64, current itype.Vec3i, skipdir itype.Direction) (ok bool, blockcoord itype.Vec3i, face itype.Direction, where itype.Vec3d, dist float64) {

	// Length test
	if current.ToFloat64().Addv(0.5, 0.5, 0.5).Add(from.Negative()).Length() > maxlen+1 {
		return
	}

	// Loose intersect test
	if ok, _, _, _ = (itype.Boxd{
		OffX:  float64(current[0]),
		OffY:  float64(current[1]),
		OffZ:  float64(current[2]),
		SizeX: 1, SizeY: 1, SizeZ: 1,
	}).IntersectRay(from, dir, maxlen); !ok {
		return
	}

	// Go through the bounding boxes
	ba := w.Block(current).Appearance(current)
	if !ba.NotSolid {
		for _, b := range ba.Lookbox {
			if ok, face, where, dist = b.Offset(current.ToFloat64()).IntersectRay(from, dir, maxlen); ok {
				blockcoord = current
				return
			}
		}
	}

	// Test the directions
	for i := itype.Direction(0); i < 6; i++ {
		if i == skipdir {
			continue
		}

		ok, blockcoord, face, where, dist = w.castworker(from, dir, maxlen, current.Add(itype.DirectionVeci[i]), i.Opposite())
		if ok {
			return
		}
	}

	ok = false
	return
}

// CastViewRay
func (w *World) CastViewRay(from, dir itype.Vec3d, maxlen float64) (ok bool, blockcoord itype.Vec3i, face itype.Direction, where itype.Vec3d, dist float64) {

	return w.castworker(from, dir, maxlen, from.Floor(), -1)
}