#define FOV	0.873	/* about 50 deg */

varying vec3 v_rorg, v_rdir;

void main()
{
	gl_Position = gl_Vertex;

	float dist = 1.0 / tan(FOV / 2.0);
	vec3 dir = vec3(gl_MultiTexCoord0.xy * 2.0 - 1.0, dist);
	v_rdir = gl_NormalMatrix * dir;
	v_rorg = (gl_ModelViewMatrix * vec4(0.0, 0.0, 0.0, 1.0)).xyz;
}