// GL Shading Language version 1.0 Vertex Shader
//  Orion Sky Lawlor, olawlor@acm.org, 2006/08/31 (Public Domain)

// C++/vertex shader interface
uniform float spin_x, spin_y;

// Vertex/fragment shader interface:
varying vec4 color; // Material diffuse color

// Input: gl_Vertex.  Output: gl_Position.
void main(void) 
{
	// Vertex positions come from the C program:
	vec4 v = gl_Vertex;
	
	float angle=spin_x;
	float s=sin(angle), c=cos(angle);
	
	mat4 m=mat4(0.0);
	m[0].x=c; m[1].x=-s;
	m[0].y=s; m[1].y=c;
	m[2].z=1.0;
	m[2].w=1.0; m[3].w=2.0; /* w= z+2.0 */
	
	gl_Position = m*v;
	// gl_Position is where onscreen the vertex will be drawn.
	
	// We'll set color the same as input position
	color=gl_Vertex;
}