root/OpenSceneGraph-Data/trunk/shaders/blocky.vert

// blocky.vert - an OGLSL vertex shader with animation
// Mike Weiblen 2003-09-16 : derived from brick.vert
// Copyright 2003 3Dlabs Inc.
// see http://www.3dlabs.com/opengl2/ for more OpenGL Shading Language info.


// the App updates uniforms "slowly" (eg once per frame) for animation.
uniform float Sine;

const vec3 LightPosition = vec3(0.0, 0.0, 4.0);
const float BlockScale = 0.30;

// varyings are written by vert shader, interpolated, and read by frag shader.
varying float LightIntensity;
varying vec2  BlockPosition;

void main(void)
{
    // per-vertex diffuse lighting
    vec4 ecPosition     = gl_ModelViewMatrix * gl_Vertex;
    vec3 tnorm          = normalize(gl_NormalMatrix * gl_Normal);
    vec3 lightVec       = normalize(LightPosition - vec3 (ecPosition));
    LightIntensity      = max(dot(lightVec, tnorm), 0.0); 

    // blocks will be determined by fragment's position on the XZ plane.
    BlockPosition = gl_Vertex.xz / BlockScale;

    // scale the geometry based on an animation variable.
    vec4 vertex = gl_Vertex;
    vertex.w    = 1.0 + 0.4 * (Sine + 1.0);

    gl_Position = gl_ModelViewProjectionMatrix * vertex;
}