combine line-width and line-gap-width in shader

This makes the values for u_linewidth and u_gapwidth independent of
eachother, which clears the way for making these properties data-driven.

line.fragment.glsl

@@ -1,23 +1,22 @@
 precision mediump float;
 
-uniform vec2 u_linewidth;
 uniform lowp vec4 u_color;
 uniform lowp float u_opacity;
 uniform float u_blur;
 
 varying vec2 v_normal;
-varying float v_linesofar;
+varying vec2 v_linewidth;
 varying float v_gamma_scale;
 
 void main() {
     // Calculate the distance of the pixel from the line in pixels.
-    float dist = length(v_normal) * u_linewidth.s;
+    float dist = length(v_normal) * v_linewidth.s;
 
     // Calculate the antialiasing fade factor. This is either when fading in
     // the line in case of an offset line (v_linewidth.t) or when fading out
     // (v_linewidth.s)
     float blur = u_blur * v_gamma_scale;
-    float alpha = clamp(min(dist - (u_linewidth.t - blur), u_linewidth.s - dist) / blur, 0.0, 1.0);
+    float alpha = clamp(min(dist - (v_linewidth.t - blur), v_linewidth.s - dist) / blur, 0.0, 1.0);
 
     gl_FragColor = u_color * (alpha * u_opacity);
 

line.vertex.glsl

@@ -12,14 +12,17 @@ attribute vec2 a_pos;
 attribute vec4 a_data;
 
 uniform mat4 u_matrix;
-uniform float u_ratio;
-uniform mediump vec2 u_linewidth;
-uniform float u_extra;
+uniform mediump float u_ratio;
+uniform mediump float u_linewidth;
+uniform mediump float u_gapwidth;
+uniform mediump float u_antialiasing;
+uniform mediump float u_extra;
 uniform mat2 u_antialiasingmatrix;
 uniform mediump float u_offset;
+uniform mediump float u_blur;
 
 varying vec2 v_normal;
-varying float v_linesofar;
+varying vec2 v_linewidth;
 varying float v_gamma_scale;
 
 void main() {
@@ -34,9 +37,12 @@ void main() {
     normal.y = sign(normal.y - 0.5);
     v_normal = normal;
 
+    float inset = u_gapwidth + (u_gapwidth > 0.0 ? u_antialiasing : 0.0);
+    float outset = u_gapwidth + u_linewidth * (u_gapwidth > 0.0 ? 2.0 : 1.0) + u_antialiasing;
+
     // Scale the extrusion vector down to a normal and then up by the line width
     // of this vertex.
-    mediump vec4 dist = vec4(u_linewidth.s * a_extrude * scale, 0.0, 0.0);
+    mediump vec4 dist = vec4(outset * a_extrude * scale, 0.0, 0.0);
 
     // Calculate the offset when drawing a line that is to the side of the actual line.
     // We do this by creating a vector that points towards the extrude, but rotate
@@ -59,5 +65,6 @@ void main() {
     // how much features are squished in all directions by the perspectiveness
     float perspective_scale = 1.0 / (1.0 - min(y * u_extra, 0.9));
 
+    v_linewidth = vec2(outset, inset);
     v_gamma_scale = perspective_scale * squish_scale;
 }

linepattern.fragment.glsl

@@ -1,6 +1,5 @@
 precision mediump float;
 
-uniform vec2 u_linewidth;
 uniform float u_point;
 uniform float u_blur;
 
@@ -16,23 +15,24 @@ uniform float u_opacity;
 uniform sampler2D u_image;
 
 varying vec2 v_normal;
+varying vec2 v_linewidth;
 varying float v_linesofar;
 varying float v_gamma_scale;
 
 void main() {
     // Calculate the distance of the pixel from the line in pixels.
-    float dist = length(v_normal) * u_linewidth.s;
+    float dist = length(v_normal) * v_linewidth.s;
 
     // Calculate the antialiasing fade factor. This is either when fading in
     // the line in case of an offset line (v_linewidth.t) or when fading out
     // (v_linewidth.s)
     float blur = u_blur * v_gamma_scale;
-    float alpha = clamp(min(dist - (u_linewidth.t - blur), u_linewidth.s - dist) / blur, 0.0, 1.0);
+    float alpha = clamp(min(dist - (v_linewidth.t - blur), v_linewidth.s - dist) / blur, 0.0, 1.0);
 
     float x_a = mod(v_linesofar / u_pattern_size_a.x, 1.0);
     float x_b = mod(v_linesofar / u_pattern_size_b.x, 1.0);
-    float y_a = 0.5 + (v_normal.y * u_linewidth.s / u_pattern_size_a.y);
-    float y_b = 0.5 + (v_normal.y * u_linewidth.s / u_pattern_size_b.y);
+    float y_a = 0.5 + (v_normal.y * v_linewidth.s / u_pattern_size_a.y);
+    float y_b = 0.5 + (v_normal.y * v_linewidth.s / u_pattern_size_b.y);
     vec2 pos = mix(u_pattern_tl_a, u_pattern_br_a, vec2(x_a, y_a));
     vec2 pos2 = mix(u_pattern_tl_b, u_pattern_br_b, vec2(x_b, y_b));
 

linepattern.vertex.glsl

@@ -17,12 +17,15 @@ attribute vec4 a_data;
 
 uniform mat4 u_matrix;
 uniform mediump float u_ratio;
-uniform mediump vec2 u_linewidth;
-uniform float u_extra;
+uniform mediump float u_linewidth;
+uniform mediump float u_gapwidth;
+uniform mediump float u_antialiasing;
+uniform mediump float u_extra;
 uniform mat2 u_antialiasingmatrix;
 uniform mediump float u_offset;
 
 varying vec2 v_normal;
+varying vec2 v_linewidth;
 varying float v_linesofar;
 varying float v_gamma_scale;
 
@@ -39,10 +42,13 @@ void main() {
     normal.y = sign(normal.y - 0.5);
     v_normal = normal;
 
+    float inset = u_gapwidth + (u_gapwidth > 0.0 ? u_antialiasing : 0.0);
+    float outset = u_gapwidth + u_linewidth * (u_gapwidth > 0.0 ? 2.0 : 1.0) + u_antialiasing;
+
     // Scale the extrusion vector down to a normal and then up by the line width
     // of this vertex.
     mediump vec2 extrude = a_extrude * scale;
-    mediump vec2 dist = u_linewidth.s * extrude;
+    mediump vec2 dist = outset * extrude;
 
     // Calculate the offset when drawing a line that is to the side of the actual line.
     // We do this by creating a vector that points towards the extrude, but rotate
@@ -66,5 +72,6 @@ void main() {
     // how much features are squished in all directions by the perspectiveness
     float perspective_scale = 1.0 / (1.0 - min(y * u_extra, 0.9));
 
+    v_linewidth = vec2(outset, inset);
     v_gamma_scale = perspective_scale * squish_scale;
 }

linesdfpattern.fragment.glsl

@@ -1,6 +1,5 @@
 precision mediump float;
 
-uniform vec2 u_linewidth;
 uniform lowp vec4 u_color;
 uniform lowp float u_opacity;
 uniform float u_blur;
@@ -9,19 +8,20 @@ uniform float u_sdfgamma;
 uniform float u_mix;
 
 varying vec2 v_normal;
+varying vec2 v_linewidth;
 varying vec2 v_tex_a;
 varying vec2 v_tex_b;
 varying float v_gamma_scale;
 
 void main() {
     // Calculate the distance of the pixel from the line in pixels.
-    float dist = length(v_normal) * u_linewidth.s;
+    float dist = length(v_normal) * v_linewidth.s;
 
     // Calculate the antialiasing fade factor. This is either when fading in
     // the line in case of an offset line (v_linewidth.t) or when fading out
     // (v_linewidth.s)
     float blur = u_blur * v_gamma_scale;
-    float alpha = clamp(min(dist - (u_linewidth.t - blur), u_linewidth.s - dist) / blur, 0.0, 1.0);
+    float alpha = clamp(min(dist - (v_linewidth.t - blur), v_linewidth.s - dist) / blur, 0.0, 1.0);
 
     float sdfdist_a = texture2D(u_image, v_tex_a).a;
     float sdfdist_b = texture2D(u_image, v_tex_b).a;

linesdfpattern.vertex.glsl

@@ -16,8 +16,10 @@ attribute vec2 a_pos;
 attribute vec4 a_data;
 
 uniform mat4 u_matrix;
-uniform mediump vec2 u_linewidth;
 uniform mediump float u_ratio;
+uniform mediump float u_linewidth;
+uniform mediump float u_gapwidth;
+uniform mediump float u_antialiasing;
 uniform vec2 u_patternscale_a;
 uniform float u_tex_y_a;
 uniform vec2 u_patternscale_b;
@@ -27,6 +29,7 @@ uniform mat2 u_antialiasingmatrix;
 uniform mediump float u_offset;
 
 varying vec2 v_normal;
+varying vec2 v_linewidth;
 varying vec2 v_tex_a;
 varying vec2 v_tex_b;
 varying float v_gamma_scale;
@@ -44,9 +47,12 @@ void main() {
     normal.y = sign(normal.y - 0.5);
     v_normal = normal;
 
+    float inset = u_gapwidth + (u_gapwidth > 0.0 ? u_antialiasing : 0.0);
+    float outset = u_gapwidth + u_linewidth * (u_gapwidth > 0.0 ? 2.0 : 1.0) + u_antialiasing;
+
     // Scale the extrusion vector down to a normal and then up by the line width
     // of this vertex.
-    mediump vec4 dist = vec4(u_linewidth.s * a_extrude * scale, 0.0, 0.0);
+    mediump vec4 dist = vec4(outset * a_extrude * scale, 0.0, 0.0);
 
     // Calculate the offset when drawing a line that is to the side of the actual line.
     // We do this by creating a vector that points towards the extrude, but rotate
@@ -72,5 +78,6 @@ void main() {
     // how much features are squished in all directions by the perspectiveness
     float perspective_scale = 1.0 / (1.0 - min(y * u_extra, 0.9));
 
+    v_linewidth = vec2(outset, inset);
     v_gamma_scale = perspective_scale * squish_scale;
 }