49               GLfloat z0, GLfloat z1, GLfloat z2, GLfloat plane[4])  in compute_plane()
70    plane[0] = a;  in compute_plane()
71    plane[1] = b;  in compute_plane()
72    plane[2] = c;  in compute_plane()
73    plane[3] = d;  in compute_plane()
81 constant_plane(GLfloat value, GLfloat plane[4])  in constant_plane()
83    plane[0] = 0.0;  in constant_plane()
84    plane[1] = 0.0;  in constant_plane()
85    plane[2] = -1.0;  in constant_plane()
86    plane[3] = value;  in constant_plane()
103 solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])  in solve_plane()
105    ASSERT(plane[2] != 0.0F);  in solve_plane()
106    return (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];  in solve_plane()
118 solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])  in solve_plane_recip()
120    const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y;  in solve_plane_recip()
124       return -plane[2] / denom;  in solve_plane_recip()
132 solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])  in solve_plane_chan()
134    const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];  in solve_plane_chan()
148 plane_dx(const GLfloat plane[4])  in plane_dx()
150    return -plane[0] / plane[2];  in plane_dx()
154 plane_dy(const GLfloat plane[4])  in plane_dy()
156    return -plane[1] / plane[2];  in plane_dy()