Re: [PyOpenGL-Users] Lighting and texturing

[Richard J. <ric...@op...>]

On Sat, 22 Sep 2001 20:15, Richard Jones wrote:
> I can't seem to figure how to have a surface lit and textured. The demo
> that comes with pyopengl (NeHe/lesson18.py) doesn't work, and my code looks
> very similar to it...
>
> Ideas?

I'm also having trouble getting things to be transparent, and I get the funny 
feeling they're related problems...

OK, this time I'll actually send some code :)

First up, the code that initialises things:
        glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
        glutInitWindowSize(self.width, self.height)
        glutCreateWindow("GLE demo")

        # display all the time
        glutDisplayFunc(self.on_display)
        glutIdleFunc(self.on_display)

        # go with both normal and passive (mouse button down and not)
        glutPassiveMotionFunc(self.on_motion)
        glutMotionFunc(self.on_motion)
        # and detect mouse clicks
        glutMouseFunc(self.on_mouse)
        # and key clicks
        glutKeyboardFunc(self.on_key)
        glutReshapeFunc(self.on_reshape)
        if '-fs' in args:
            glutFullScreen()

        # set up the display specifics
        glClearDepth(1.0)
        glEnable(GL_DEPTH_TEST)
        glClearColor(0.0, 0.0, 0.0, 0.0)
        glShadeModel(GL_FLAT)

        glMatrixMode(GL_MODELVIEW)

        # initialize lighting
        glLightfv(GL_LIGHT0, GL_POSITION,  (-40.0, 40, -100.0, 0.0))
        glLightfv(GL_LIGHT0, GL_DIFFUSE, (0.99, 0.99, 0.99, 1.0))
        glEnable(GL_LIGHT0)
        glLightfv(GL_LIGHT1, GL_POSITION, (-100.0, 40, -40.0, 0.0))
        glLightfv(GL_LIGHT1, GL_DIFFUSE, (0.99, 0.99, 0.99, 1.0))
        glEnable(GL_LIGHT1)
        glEnable(GL_LIGHTING)

        glColorMaterial(GL_FRONT_AND_BACK, GL_DIFFUSE)
        glEnable(GL_COLOR_MATERIAL)



Now, the code that is supposed to light and texture map surfaces:

        self.texture = Image.open('texmap_256.png')
        ix, iy = self.texture.size
        image = self.texture.tostring("raw", "RGB", 0, -1)
        self.maptex = glGenTextures(1)
        glBindTexture(GL_TEXTURE_2D, self.maptex)
        glPixelStorei(GL_UNPACK_ALIGNMENT,1)
        glTexImage2D(GL_TEXTURE_2D, 0, 3, ix, iy, 0, GL_RGB,
            GL_UNSIGNED_BYTE, image)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
        glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL)
        print "... done"

... later ...

        glPushMatrix()
        glEnable(GL_TEXTURE_2D)
        glBindTexture(GL_TEXTURE_2D, self.maptex)
        glEnable(GL_LIGHTING)
        glShadeModel(GL_FLAT)

        [ "i" loop ]
            [ "j" loop ]
                glBegin(GL_TRIANGLES)
                norm1, norm2, p1, p2, p3, p4 = z_row[j]

                glNormal(*norm1)

                glTexCoord2f(i*4./256., j*4./256.)
                glVertex(*p1)
                glTexCoord2f(i*4./256., (j*4.+4)/256.)
                glVertex(*p2)
                glTexCoord2f((i*4.+4)/256., (j*4.+4)/256.)
                glVertex(*p3)

                glNormal(*norm2)
                glTexCoord2f(i*4./256., j*4./256.)
                glVertex(*p1)
                glTexCoord2f((i*4.+4)/256., (j*4.+4)/256.)
                glVertex(*p3)
                glTexCoord2f((i*4.+4)/256., j*4./256.)
                glVertex(*p4)
                glEnd()
        glDisable(GL_TEXTURE_2D)



Next up, the code that is supposed to use a texture with an alpha channel:

        self.texture = Image.open('point_64.png')
        ix, iy = self.texture.size
        image = self.texture.tostring("raw", "RGBA", 0, -1)
        self.pointtex = glGenTextures(1)
        glBindTexture(GL_TEXTURE_2D, self.pointtex)
        glPixelStorei(GL_UNPACK_ALIGNMENT,1)
        glTexImage2D(GL_TEXTURE_2D, 0, 3, ix, iy, 0, GL_RGBA,
           GL_UNSIGNED_BYTE, image)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR)
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
        glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL)

... later ...
 
        glEnable(GL_TEXTURE_2D)
        glBindTexture(GL_TEXTURE_2D, self.pointtex)
        glDisable(GL_LIGHTING)
        glBegin(GL_QUADS)
        [ loop ]
            glTexCoord2f(0, 0)
            glVertex3f(x, y, z)
            glTexCoord2f(1, 0)
            glVertex3f(x+2, y, z)
            glTexCoord2f(1, 1)
            glVertex3f(x+2, y+2, z)
            glTexCoord2f(0, 1)
            glVertex3f(x, y+2, z)
        glEnd()
        glEnable(GL_LIGHTING)
        glDisable(GL_TEXTURE_2D)


I've also attached the point_64.png image, generated in the GIMP. I'm 
_pretty_ sure it's transparent - unlike Photoshop, the GIMP doesn't show me 
the alpha channel explicitly (unless I'm doing something wrong, which is 
possible :)

I can post the complete code, but it's supposed to be a surprise :)


    Richard