color_relief.vertex.glsl

uniform vec2 u_dimension;

in vec2 a_pos;

out vec2 v_pos;

void main() {
    gl_Position = projectTile(a_pos, a_pos);
    highp vec2 epsilon = 1.0 / u_dimension;
    float scale = (u_dimension.x - 2.0) / u_dimension.x;
    v_pos = (a_pos / 8192.0) * scale + epsilon;
    // North pole
    if (a_pos.y < -32767.5) {
        v_pos.y = 0.0;
    }
    // South pole
    if (a_pos.y > 32766.5) {
        v_pos.y = 1.0;
    }
}