71 lines
2.9 KiB
GLSL
71 lines
2.9 KiB
GLSL
uniform lowp float u_device_pixel_ratio;
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uniform vec2 u_texsize;
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uniform float u_fade;
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uniform mediump vec4 u_scale;
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uniform sampler2D u_image;
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in vec2 v_normal;
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in vec2 v_width2;
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in float v_linesofar;
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in float v_gamma_scale;
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#pragma mapbox: define lowp vec4 pattern_from
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#pragma mapbox: define lowp vec4 pattern_to
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#pragma mapbox: define lowp float blur
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#pragma mapbox: define lowp float opacity
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void main() {
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#pragma mapbox: initialize mediump vec4 pattern_from
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#pragma mapbox: initialize mediump vec4 pattern_to
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#pragma mapbox: initialize lowp float blur
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#pragma mapbox: initialize lowp float opacity
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vec2 pattern_tl_a = pattern_from.xy;
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vec2 pattern_br_a = pattern_from.zw;
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vec2 pattern_tl_b = pattern_to.xy;
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vec2 pattern_br_b = pattern_to.zw;
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float pixelRatio = u_scale.x;
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float tileZoomRatio = u_scale.y;
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float fromScale = u_scale.z;
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float toScale = u_scale.w;
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vec2 display_size_a = vec2((pattern_br_a.x - pattern_tl_a.x) / pixelRatio, (pattern_br_a.y - pattern_tl_a.y) / pixelRatio);
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vec2 display_size_b = vec2((pattern_br_b.x - pattern_tl_b.x) / pixelRatio, (pattern_br_b.y - pattern_tl_b.y) / pixelRatio);
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vec2 pattern_size_a = vec2(display_size_a.x * fromScale / tileZoomRatio, display_size_a.y);
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vec2 pattern_size_b = vec2(display_size_b.x * toScale / tileZoomRatio, display_size_b.y);
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// Calculate the distance of the pixel from the line in pixels.
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float dist = length(v_normal) * v_width2.s;
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// Calculate the antialiasing fade factor. This is either when fading in
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// the line in case of an offset line (v_width2.t) or when fading out
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// (v_width2.s)
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float blur2 = (blur + 1.0 / u_device_pixel_ratio) * v_gamma_scale;
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float alpha = clamp(min(dist - (v_width2.t - blur2), v_width2.s - dist) / blur2, 0.0, 1.0);
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float x_a = mod(v_linesofar / pattern_size_a.x, 1.0);
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float x_b = mod(v_linesofar / pattern_size_b.x, 1.0);
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// v_normal.y is 0 at the midpoint of the line, -1 at the lower edge, 1 at the upper edge
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// we clamp the line width outset to be between 0 and half the pattern height plus padding (2.0)
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// to ensure we don't sample outside the designated symbol on the sprite sheet.
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// 0.5 is added to shift the component to be bounded between 0 and 1 for interpolation of
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// the texture coordinate
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float y_a = 0.5 + (v_normal.y * clamp(v_width2.s, 0.0, (pattern_size_a.y + 2.0) / 2.0) / pattern_size_a.y);
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float y_b = 0.5 + (v_normal.y * clamp(v_width2.s, 0.0, (pattern_size_b.y + 2.0) / 2.0) / pattern_size_b.y);
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vec2 pos_a = mix(pattern_tl_a / u_texsize, pattern_br_a / u_texsize, vec2(x_a, y_a));
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vec2 pos_b = mix(pattern_tl_b / u_texsize, pattern_br_b / u_texsize, vec2(x_b, y_b));
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vec4 color = mix(texture(u_image, pos_a), texture(u_image, pos_b), u_fade);
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fragColor = color * alpha * opacity;
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#ifdef OVERDRAW_INSPECTOR
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fragColor = vec4(1.0);
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#endif
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}
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