uniform mat4 u_matrix;
uniform vec2 u_pixel_coord_upper;
uniform vec2 u_pixel_coord_lower;
uniform vec4 u_scale;

attribute vec2 a_pos;

varying vec2 v_pos_a;
varying vec2 v_pos_b;

#pragma mapbox: define lowp float opacity
#pragma mapbox: define lowp vec4 pattern_from
#pragma mapbox: define lowp vec4 pattern_to

void main() {
    #pragma mapbox: initialize lowp float opacity
    #pragma mapbox: initialize mediump vec4 pattern_from
    #pragma mapbox: initialize mediump vec4 pattern_to

    vec2 pattern_tl_a = pattern_from.xy;
    vec2 pattern_br_a = pattern_from.zw;
    vec2 pattern_tl_b = pattern_to.xy;
    vec2 pattern_br_b = pattern_to.zw;

    float pixelRatio = u_scale.x;
    float tileZoomRatio = u_scale.y;
    float fromScale = u_scale.z;
    float toScale = u_scale.w;

    vec2 display_size_a = vec2((pattern_br_a.x - pattern_tl_a.x) / pixelRatio, (pattern_br_a.y - pattern_tl_a.y) / pixelRatio);
    vec2 display_size_b = vec2((pattern_br_b.x - pattern_tl_b.x) / pixelRatio, (pattern_br_b.y - pattern_tl_b.y) / pixelRatio);
    gl_Position = u_matrix * vec4(a_pos, 0, 1);

    v_pos_a = get_pattern_pos(u_pixel_coord_upper, u_pixel_coord_lower, fromScale * display_size_a, tileZoomRatio, a_pos);
    v_pos_b = get_pattern_pos(u_pixel_coord_upper, u_pixel_coord_lower, toScale * display_size_b, tileZoomRatio, a_pos);
}