src/mbgl/shader/outlinepattern.fragment.glsl


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uniform float u_opacity;
uniform vec2 u_pattern_tl_a;
uniform vec2 u_pattern_br_a;
uniform vec2 u_pattern_tl_b;
uniform vec2 u_pattern_br_b;
uniform float u_mix;

uniform sampler2D u_image;

varying vec2 v_pos_a;
varying vec2 v_pos_b;
varying vec2 v_pos;

void main() {
    vec2 imagecoord = mod(v_pos_a, 1.0);
    vec2 pos = mix(u_pattern_tl_a, u_pattern_br_a, imagecoord);
    vec4 color1 = texture2D(u_image, pos);

    vec2 imagecoord_b = mod(v_pos_b, 1.0);
    vec2 pos2 = mix(u_pattern_tl_b, u_pattern_br_b, imagecoord_b);
    vec4 color2 = texture2D(u_image, pos2);

    // find distance to outline for alpha interpolation

    float dist = length(v_pos - gl_FragCoord.xy);
    float alpha = smoothstep(1.0, 0.0, dist);
    

    gl_FragColor = mix(color1, color2, u_mix) * alpha * u_opacity;
}