get_camera_matrices.py

#!/usr/bin/env python

"""
Get camera matrices.

This an example showing how to obtain the modelview and projection matrices
for the Panda3D camera pose and "lens" settings used by seeing3d.
As a side effect a window may pop-up; ignore it.

"""

import os
import argparse
import pprint

import numpy as np
import matplotlib.pyplot as pl
import path

import model

from pandac.PandaModules import *

WIDTH = 600
HEIGHT = 600
FOCAL_LENGTH_IN = 1.37795276 # 35 mm
loadPrcFileData('', 'win-size %d %d'%(WIDTH, HEIGHT))
loadPrcFileData('', 'win-fixed-size #t')

from direct.showbase.ShowBase import ShowBase

def obj_centered_camera_pose(rho_in, phi_deg, theta_deg):
    phi, theta = np.radians((phi_deg, theta_deg))
    x = (rho_in * np.cos(theta) * np.cos(phi))
    y = (rho_in * np.sin(theta) * np.cos(phi))
    z = (rho_in * np.sin(phi))
    base.cam.setPos(x, y, z)
    base.cam.lookAt(Point3(0, 0, 0))

def as_numpy(A):
    a = np.asarray([ [A(i,j) for j in xrange(4)] for i in xrange(4) ] )
    return a

base = ShowBase()
base.camLens.setFov(54.611362) #from sketchup fov
base.camLens.setFocalLength(FOCAL_LENGTH_IN)

rho_in = 12*8
phi_deg = 20
theta_deg = 0

# arrange the model and the camera pose
obj_centered_camera_pose(rho_in, phi_deg, theta_deg)

C = as_numpy(Mat4.convertMat(CSYupRight, base.camLens.getCoordinateSystem()))
P = as_numpy(base.camLens.getProjectionMat())
proj = np.dot(C, P)

print('projection matrix = ')
print(proj)

gsg = base.win.getGsg()
S = as_numpy(Mat4.convertMat(gsg.getCoordinateSystem(), CSYupRight))
V = as_numpy(base.cam.getMat())
M = np.linalg.inv(V)
modelview = np.dot(M, S)

print('modelview matrix = ')
print(modelview)