Check for intersection with bounding boxes and ray

rayboundingbox.py

import numpy as np
import math

vec = (1.3*4, -2.7*4, 0)
start = (1,1,0)

bb = (2,-3, -1)
bbSize = (1,1,2)

xStep = 1
yStep = 1
zStep = 1

subX = 0
subY = 0
subZ = 0

if vec[0] > 0:
    subX = 1

if vec[1] > 0:
    subY = 1

if vec[2] > 0:
    subZ = 1

if vec[0] < 0: xStep = -1
if vec[1] < 0: yStep = -1
if vec[2] < 0: zStep = -1

# Calculate intersection planes
xPlanes = list(np.arange(0, vec[0], xStep)) + [vec[0]]
yPlanes = list(np.arange(0, vec[1], yStep)) + [vec[1]] 
zPlanes = list(np.arange(0, vec[2], zStep)) + [vec[2]]

intercepts = []

if vec[0] != 0:
    for xi in xPlanes:
        factor = xi/vec[0]
        yi = vec[1] * factor
        zi = vec[2] * factor
        intercepts.append((math.floor(xi-subX+start[0]),math.floor(yi+start[1]),math.floor(zi+start[2])))

if vec[1] != 0:
    for yi in yPlanes:
        factor = yi/vec[1]
        xi = vec[0] * factor
        zi = vec[2] * factor
        intercepts.append((math.floor(xi+start[0]),math.floor(yi-subY+start[1]),math.floor(zi+start[2])))

if vec[2] != 0:
    for zi in zPlanes:
        factor = zi/vec[2]
        xi = vec[0] * factor
        yi = vec[1] * factor
        intercepts.append((math.floor(xi+start[0]),math.floor(yi+start[1]),math.floor(zi-subZ+start[2])))

# Translate bounding box
bbOff = (bb[0] - start[0], bb[1] - start[1], bb[2] - start[2])

# Intersect X
if vec[0] != 0:
    xFac = bbOff[0] / vec[0]
    yix = vec[1] * xFac + start[1]
    zix = vec[2] * xFac + start[2]

    if (yix > bb[1] and yix < bb[1] + bbSize[1] and zix > bb[2] and zix < bb[2] + bbsize[2]):
        print("Intercept at (" + str(bbOff[0] + start[0]) + ", " + str(yix) + ", " + str(yix) + ")")

# Intersect Y
if vec[1] != 0:
    yFac = bbOff[1] / vec[1]
    xiy = vec[0] * yFac + start[0]
    ziy = vec[2] * yFac + start[2]

    if (xiy > bb[0] and xiy < bb[0] + bbSize[0] and ziy > bb[2] and ziy < bb[2] + bbSize[2]):
        print("Intercept at (" + str(xiy) + ", " + str(bbOff[1] + start[1]) + ", " +  str(ziy) + ")")


# Intersect Z
if vec[2] != 0:
    zFac = bbOff[2] / vec[2]
    xiz = vec[0] * zFac + start[0]
    yiz = vec[1] * zFac + start[1]

    if (xiz > bb[0] and xiz < bb[0] + bbSize[0] and yiz > bb[1] and yiz < bb[1] + bbSize[1]):
        print("Intercept at (" + str(xiz) + ", " + str(yiz) + ", " + str(bbOff[2] + start[2]) + ")")