Test is a given point is visible in the camera and Convert between 3d and screen coordinates

pointInCamera.py

# Test is a given point is visible in the camera
# Convert between 3d and screen coordinates

import modo

# Assuming the camera is also the active view
def pointInCamera(cam, position):

	aperture_x = cam.channel(lx.symbol.sICHAN_CAMERA_APERTUREX).get()
	aperture_y = cam.channel(lx.symbol.sICHAN_CAMERA_APERTUREY).get()

	sv = lx.service.View3Dport()
	view = lx.object.View3D( sv.View(sv.Current()) )
	zeroa, zerob, width, height = view.Bounds()
	print 'View dimensions in pixels: ', width, height 


	# Multiply position with camera matrix
	mat1 = modo.Matrix4(position=position)
	mat2 = modo.Matrix4(modo.Camera('Camera').channel('worldMatrix').get())
	mat3 = mat1 * mat2.inverted()
	posInCamSpace = modo.Vector3(mat3.position).normal()

	# Bail out if point is behind of the camera
	if not posInCamSpace < 0.0:
		return False

	# Convert to screen coordinates (optionally)
	x = ( posInCamSpace.x / (-posInCamSpace.z) ) / 10.0 / aperture_x
	y = ( posInCamSpace.y / (-posInCamSpace.z) ) / 10.0 / aperture_y
	print x,y 

	xpos = (( x + 1.0) / 2.0) * float(width)
	ypos = (( y + 1.0) / 2.0) * float(height)
	print 'x coordinate: ', xpos
	print 'y coordinate: ', ypos

	# Point is visible if x and y values are in range -1.0 to +1.0
	return abs(x) <= 1.0 and abs(y) <= 1.0


scene = modo.Scene()

# Create a locator if it does not exist
try:
	scene.ItemLookup('Locator')
except LookupError:
	locator = scene.addItem(lx.symbol.sITYPE_LOCATOR)

cam = modo.Camera('Camera')
pos = locator.position.get()

# Move the locator around and run the script in the script editor to test
print pointInCamera(cam, pos )