// 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 texscale;
uniform mat4 modelMat; // Object transform (world from model)
uniform mat4 clipMat; // Overall clip-space transform (clip from model)
uniform vec4 cameraLoc; // Location of camera

// Vertex/fragment shader interface:
varying vec4 color; // Material diffuse color
varying vec3 position; // World-space coordinates of object
varying vec3 normal; // Surface normal
varying vec3 cameraDir; // Points toward camera
varying vec2 texCoord; // Texture coordinates

// Input: gl_Vertex.  Output: gl_Position.
void main(void) 
{
	// Output "varying" for fragment shader:
	color=gl_Color;
	// Transform position and normal to world coordinates
	position=vec3(modelMat*gl_Vertex);
	normal=normalize(vec3(modelMat*vec4(gl_Normal,0)));
	// Compute vector pointing toward camera
	cameraDir=normalize(vec3(cameraLoc)-position);
	texCoord=(vec2(position)*0.5+0.5)*texscale; /* shift from [-1,+1] to [0,texscale] */
	
	// Compute clip coordinates straight from model coordinates
	gl_Position = clipMat*gl_Vertex;
}