#version 120

uniform mat4 trans; // local space to clip space
uniform vec3 dx; // "right" change of basis vector
uniform vec3 dy; // "up" change of basis vector
uniform vec3 particle_position;
uniform float scale;

attribute vec2 quad_texture;
attribute float age;

void main()
{
  // calculate unit quad position coordinates from texture coordinates
  vec2 quad_position = quad_texture * 2 + 1;

  vec3 position = particle_position;
  position += position.xxx * dx;
  position += position.yyy * dy;
  position *= scale;

  position = trans * position;

  gl_Position = vec4(position, 1);
  gl_TexCoord[0] = vec4(quad_texture, 0, age);
}