uniform mat4 u_matrix;
uniform vec2 u_pattern_size_a;
uniform vec2 u_pattern_size_b;
uniform vec2 u_pixel_coord_upper;
uniform vec2 u_pixel_coord_lower;
uniform float u_scale_a;
uniform float u_scale_b;
uniform float u_tile_units_to_pixels;

attribute vec2 a_pos;

varying vec2 v_pos_a;
varying vec2 v_pos_b;

void main() {
    gl_Position = u_matrix * vec4(a_pos, 0, 1);

    v_pos_a = get_pattern_pos(u_pixel_coord_upper, u_pixel_coord_lower, u_scale_a * u_pattern_size_a, u_tile_units_to_pixels, a_pos);
    v_pos_b = get_pattern_pos(u_pixel_coord_upper, u_pixel_coord_lower, u_scale_b * u_pattern_size_b, u_tile_units_to_pixels, a_pos);

#ifdef FOG
    v_fog_pos = fog_position(a_pos);
#endif
}
