OpenGL 纹理投影穿过表面

Question

我是新来的，也是 openGL 的新手。我想开发某种查看器，它加载 .ply 文件、图像作为纹理，并将其投影到网格中。我想问一下纹理投影。加载纹理和设置纹理投影的代码如下：

def loadTexture():
   # load the image
   imdata = 0
   imname = 'Cropped_Image26904_2.jpg'
   texture = glGenTextures(1)
   im = cv2.imread(imname)
   imdata = cv2.cvtColor(im, cv2.COLOR_BGR2RGB)
   # bind texture
   glBindTexture(GL_TEXTURE_2D, texture)
   glTexImage2D( GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, imdata.shape[1],
   imdata.shape[0], 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, imdata)
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, 
   GL_CLAMP_TO_BORDER)
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, 
   GL_CLAMP_TO_BORDER)
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, 
   GL_CLAMP_TO_BORDER)
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, 
   GL_CLAMP_TO_BORDER)
   gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, imdata.shape[1], 
   imdata.shape[0], GL_RGB, GL_UNSIGNED_BYTE, imdata)
   # set the 'projector' location that project the texture
   glMatrixMode(GL_PROJECTION)
   glPushMatrix()
   glLoadIdentity()
   gluPerspective(fov, 
   float(glutGet(GLUT_WINDOW_WIDTH))/glutGet(GLUT_WINDOW_HEIGHT), .1, 
   1e8)
   gluLookAt(0,0,1, 0,0,0, 0,1,0)
   mat3 = glGetFloatv(GL_PROJECTION_MATRIX)
   # mapping the texture
   glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR)
   glTexGenfv(GL_S, GL_EYE_PLANE, mat3[0])
   glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR)
   glTexGenfv(GL_T, GL_EYE_PLANE, mat3[1])
   glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR)
   glTexGenfv(GL_R, GL_EYE_PLANE, mat3[2])
   glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR)
   glTexGenfv(GL_Q, GL_EYE_PLANE, mat3[3])
   # enable the texture
   glEnable(GL_TEXTURE_2D)
   glEnable(GL_TEXTURE_GEN_S)
   glEnable(GL_TEXTURE_GEN_T)
   glEnable(GL_TEXTURE_GEN_R)
   glEnable(GL_TEXTURE_GEN_Q)

这个在某种程度上工作得很好。这是它的屏幕截图： The viewer form front. The pink ball is the 'projector' position

问题是投影的纹理穿过盒子并且还在盒子的背面留下了投影： The texture also projected to the backside of the cube

那么，问题来了，如何让纹理的投影只出现在'projector'可见的面上呢？非常感谢。

Answer 1

So, the question is, how to make the projection of the texture only appears on the face that visible to the 'projector'? Thank you very much.

绘制盒子的背面时禁用纹理。

或者你希望盒子上出现阴影？ OpenGL 不是在整个场景上运行的全局照明渲染器。事实上，OpenGL 只是一支美化的铅笔，一次绘制一个点、线或三角形，它们之间没有任何交互，除了它们对帧缓冲区中像素值的影响。

OpenGL 纹理投影穿过表面

OpenGL Texture Projection Go Through Surface

python

opengl

textures

projection