射在平坦表面上的射燈

我想在平坦的表面上照射好的聚光燈。我知道每個頂點都進行了照明，因此在表面上創建了可能的頂點 - 請參閱此answer。然而，我得到了這些 - 用GL_QUADS和GL_LINE_STRIP來檢查我是否正確地做了事情。射在平坦表面上的射燈

enter image description here

這些顯然比較差。所以，

什麼需要我的機會，使聚光燈看起來更像一個圓形的表面？
如何更快地繪製這個場景？

注：我認識到，在這種情況下，正常計算並非嚴格必要，但在一般情況下，它是需要的。另外，我可以使用表面的顯示列表，因此只能繪製一次。

#!/usr/bin/env python 
# -*- coding: utf-8 -*- 
import sys 
from OpenGL.GLUT import * 
from OpenGL.GL import * 
from OpenGL.GLU import * 
import numpy as np 
from Numeric import * 

lightPosition = np.array([10, 30, 20, 1]) 
view_rotation = np.array([0, 0, 0]) 

def init(): 
    globAmb = [0.3, 0.3, 0.3, 1.0] 
    lightAmb = [0.0, 0.0, 0.0, 1.0] 
    lightDifAndSpec = [0.7, 0.7, 0.7, 1.0] 

    glutInit() 

    glClearColor(0.0, 0.0, 0.0, 0.0) 

    glEnable(GL_DEPTH_TEST) 
    glClearDepth(1.0) 
    glDepthFunc(GL_LESS) 

    glShadeModel(GL_SMOOTH) 

    glEnable(GL_LIGHTING) 
    glLightfv(GL_LIGHT0, GL_AMBIENT, lightAmb) 
    glLightfv(GL_LIGHT0, GL_DIFFUSE, lightDifAndSpec) 
    glLightfv(GL_LIGHT0, GL_SPECULAR, lightDifAndSpec) 
    glEnable(GL_LIGHT0) 
    glLightModelfv(GL_LIGHT_MODEL_AMBIENT, globAmb) 
    glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_TRUE) 

    glEnable(GL_CULL_FACE) 
    glCullFace(GL_BACK) 


def display(): 
    glClearColor(0.0, 0.0, 0.0, 0.0) 
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) 

    glLoadIdentity() 
    gluLookAt(0.0, 40.0, 40.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); 

    glRotatef(view_rotation[0], 1.0, 0.0, 0.0) 
    glRotatef(view_rotation[1], 0.0, 1.0, 0.0) 
    glRotatef(view_rotation[2], 0.0, 0.0, 1.0) 

    glPushMatrix() 
    pos = [0, 20, 0, 1] 
    direction = [0.0, -1.0, 0.0] 
    spotAngle = 20 
    glLightfv(GL_LIGHT0, GL_POSITION, pos) 
    glLightf(GL_LIGHT0, GL_SPOT_CUTOFF, spotAngle) 
    glLightfv(GL_LIGHT0, GL_SPOT_DIRECTION, direction) 
    glLightf(GL_LIGHT0, GL_SPOT_EXPONENT, 2) 

    glPushMatrix(); 
    glDisable(GL_LIGHTING) 
    glTranslate(pos[0], 0.5* pos[1], pos[2]) 
    glRotatef(-90.0, 1.0, 0.0, 0.0) 
    glColor3f(1.0, 1.0, 1.0) 
    PI = 3.141592 
    glutWireCone(3.0 * np.tan(spotAngle/180.0 * PI), pos[1], 10, 6) 
    glEnable(GL_LIGHTING) 
    glPopMatrix(); 

    draw_cube() 

    glPopMatrix() 
    glFlush() 


def reshape(w, h): 
    glMatrixMode(GL_PROJECTION) 
    glLoadIdentity() 
    gluPerspective(45.0, float(w)/float(h), 0.1, 100.0) 
    glMatrixMode(GL_MODELVIEW) 


def keyboard(key, x, y): 
    if key == chr(27): 
     sys.exit(0) 
    elif key == 'w': 
     view_rotation[0] += 10 
     display() 
    elif key == 's': 
     view_rotation[0] -= 10 
     display() 
    elif key == 'a': 
     view_rotation[1] -= 10 
     display() 
    elif key == 'd': 
     view_rotation[1] += 10 
     display() 
    else: 
     print "Unknown %s key" %(key) 

def draw_cube(): 
    glPushMatrix() 
    glRotatef(45, 0, 1, 0) 
    glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, [183/256.0, 65/256.0, 14/256.0, 1.0]); 
    glMaterialfv(GL_FRONT, GL_SPECULAR, [1, 1, 1, 1]); 
    glMaterialfv(GL_FRONT, GL_SHININESS, [100.0]); 
    sz = 10 
    step = 1 
    for x in arange(-sz, sz, step): 
     for z in arange(-sz, sz, step): 

      v0 = np.array([x, sz, z]) 
      v1 = np.array([x, sz, z+step]) 
      v2 = np.array([x+step, sz, z+step]) 
      v3 = np.array([x+step, sz, z]) 

      #glBegin(GL_QUADS) # Uncomment to get the surface instead of lines. 
      glBegin(GL_LINE_STRIP) 

      n = get_normal_vector(v0, v1, v3) 
      glNormal(n[0], n[1], n[2]) 
      glVertex3f(v0[0], v0[1], v0[2]) 

      n = get_normal_vector(v1, v2, v0) 
      glNormal(n[0], n[1], n[2]) 
      glVertex3f(v1[0], v1[1], v1[2]) 

      n = get_normal_vector(v2, v3, v1) 
      glNormal(n[0], n[1], n[2]) 
      glVertex3f(v2[0], v2[1], v2[2]) 

      n = get_normal_vector(v3, v0, v2) 
      glNormal(n[0], n[1], n[2]) 
      glVertex3f(v3[0], v3[1], v3[2]) 
      glEnd() 

    glPopMatrix() 




def get_normal_vector (v1, v2, v3): 
    v = np.cross(v2-v1, v3-v1) 
    n = np.sqrt(np.dot(v, v.conj())) 
    if n: 
     return v/n 
    else: 
     print v1 
     print v2 
     print v3 
     print v/n 
     sys.exit(-1) 


glutInit(sys.argv) 
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB) 
glutInitWindowSize(800, 800) 
glutInitWindowPosition(300, 0) 
glutCreateWindow('Lines') 
init() 
glutDisplayFunc(display) 
glutReshapeFunc(reshape) 
glutKeyboardFunc(keyboard) 
glutMainLoop()

PS：我會使用着色器時，我有它的工作更新與源代碼的答案...

來源

2012-07-05 Sardathrion