shader_vert_earthquake

//Shaders that will do anything to do nothing
//Ludwik Janiuk

uniform float time;
varying vec4 myGlobalColor;

float rand(vec2 co)
{
    float a = 12.9898;
    float b = 78.233;
    float c = 43758.5453;
    float dt= dot(co.xy ,vec2(a,b));
    float sn= mod(dt,3.14);
    return fract(sin(sn) * c);
}

void main() {

    gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
    gl_Position = ftransform();
    myGlobalColor = gl_Color;
    float t = time/1000.0;
    float damping = 80.0;
    gl_Position.x += rand(gl_Position.yx + vec2(t, t))/damping;
	gl_Position.y += rand(gl_Position.xy + vec2(t, t))/damping;
}