// 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, aspect;

// Vertex/fragment shader interface:
varying vec4 color; // Material diffuse color
varying vec3 normal; // Surface normal

// Input: gl_Vertex.  Output: gl_Position.
void main(void) 
{
	// Vertex positions come from the C program:
	vec4 v1 = gl_Vertex;
	
	mat4 m1=mat4(0.0);
	mat4 m2=mat4(0.0);
	mat4 m3=mat4(0.0);
	
	{
	float angle=spin_x*1.0*6.28;
	float c=cos(angle), s=sin(angle);
	//v2.z = cos(angle)*v1.z + -sin(angle)*v1.y; 
	//v2.y = sin(angle)*v1.z +  cos(angle)*v1.y;

	m1[0].x=1.0;
	m1[2].z=c;
	m1[2].y=s;
	m1[1].z=-s;
	m1[1].y=c;
	m1[3].w=1.0;
	}
	
	{
	float angle=spin_y*1.0*6.28;
	float c=cos(angle), s=sin(angle);
	//v3.z = cos(angle)*v2.z + -sin(angle)*v2.x; 
	//v3.x = sin(angle)*v2.z +  cos(angle)*v2.x;
	
	m2[1].y=1.0;
	m2[2].z=c;
	m2[2].x=s;
	m2[0].z=-s;
	m2[0].x=c;
	m2[3].w=1.0;
	}
	
	// Perspective matrix
	m3[0].x=aspect;
	m3[1].y=1.0;
	m3[2].z=0.1;
	m3[2].w=1.0;
	m3[3].w=1.9;
	
	/* Transform normal by same matrices as position, but 
	  skip the perspective step, and any translations (set w==0.0) */
	//normal=normalize(vec3(m2*m1*vec4(gl_Normal,0.0)));
	/* Simple version: Just use fixed normals */
	normal=normalize(gl_Normal);
	
	gl_Position = m3*m2*m1*v1;
	// gl_Position is where onscreen the vertex will be drawn.
	
	// We'll set color the same as input position
	color=gl_Color;
}