add linecaps (GLMakie, CairoMakie)

GLMakie/assets/shader/line_segment.geom

@@ -17,6 +17,7 @@ out float f_thickness;
 out vec4 f_color;
 out vec2 f_uv;
 flat out uvec2 f_id;
+flat out int f_type;
 
 #define AA_THICKNESS 2.0
 
@@ -33,6 +34,7 @@ void emit_vertex(vec2 position, vec2 uv, int index)
  gl_Position = vec4((position / resolution) * inpos.w, inpos.z, inpos.w);
  f_id = g_id[index];
  f_thickness = g_thickness[index] + AA_THICKNESS;
+ f_type = 0;
  EmitVertex();
 }
 

GLMakie/assets/shader/lines.frag

@@ -10,6 +10,7 @@ in vec4 f_color;
 in vec2 f_uv;
 in float f_thickness;
 flat in uvec2 f_id;
+flat in int f_type; // TODO bad for performance
 {{pattern_type}} pattern;
 
 uniform float pattern_length;
@@ -26,6 +27,7 @@ float aastep(float threshold1, float threshold2, float value) {
 }
 void write2framebuffer(vec4 color, uvec2 id);
 
+// Signed distance fields for lines
 // x/y pattern
 float get_sd(sampler2D pattern, vec2 uv){
  return texture(pattern, uv).x;
@@ -40,10 +42,48 @@ vec2 get_sd(Nothing _, vec2 uv){
  return vec2(0.5, uv.y);
 }
 
+// Signed distance fields for caps
+#define LINE 0
+#define CIRCLE 4
+#define RECTANGLE 5
+#define TRIANGLE 6
+
+float triangle(vec2 P){
+ // adjusted from distance shape to fill TODO (0..0.5, 0..1)
+ // reused for 
+ P -= vec2(0.5);
+ float x = P.y - P.x;
+ float y = P.y + P.x;
+ return 0.5 - max(abs(x), abs(y));
+}
+float circle(vec2 uv){
+ // Radius 0.5 circle centered at (0.5, 0.5)
+ return 0.5-length(uv - vec2(0.5));
+}
+float rectangle(vec2 uv){
+ // fills 0..1 x 0..1
+ vec2 d = max(-uv, uv-vec2(1));
+ return -( length(max(vec2(0.0), d)) + min(0.0, max(d.x, d.y)) );
+}
+
+
 void main(){
- vec2 xy = get_sd(pattern, f_uv);
- float alpha = aastep(0, xy.x);
- float alpha2 = aastep(-1, 1, xy.y);
- vec4 color = vec4(f_color.rgb, f_color.a*alpha*alpha2);
+ vec4 color = vec4(f_color.rgb, 0.0);
+ if (f_type == CIRCLE){
+ float sd = f_thickness * circle(f_uv);
+ color = mix(color, f_color, smoothstep(-ALIASING_CONST, ALIASING_CONST, sd));
+ } else if (f_type == RECTANGLE) {
+ float sd = f_thickness * rectangle(f_uv);
+ // color = mix(color, f_color, smoothstep(-ALIASING_CONST, ALIASING_CONST, sd));
+ color = mix(color, f_color, aastep(0, sd));
+ } else if (f_type == TRIANGLE) {
+ float sd = f_thickness * triangle(f_uv);
+ color = mix(color, f_color, smoothstep(-ALIASING_CONST, ALIASING_CONST, sd));
+ } else {
+ vec2 xy = get_sd(pattern, f_uv);
+ float alpha = aastep(0, xy.x);
+ float alpha2 = aastep(-1, 1, xy.y);
+ color = vec4(f_color.rgb, f_color.a*alpha*alpha2);
+ }
  write2framebuffer(color, f_id);
 }

GLMakie/assets/shader/lines.geom

@@ -5,7 +5,7 @@
 {{GLSL_EXTENSIONS}}
 
 layout(lines_adjacency) in;
-layout(triangle_strip, max_vertices = 7) out;
+layout(triangle_strip, max_vertices = 15) out;
 
 in vec4 g_color[];
 in float g_lastlen[];
@@ -17,6 +17,7 @@ out vec2 f_uv;
 out float f_thickness;
 
 flat out uvec2 f_id;
+flat out int f_type;
 
 uniform vec2 resolution;
 uniform float maxlength;
@@ -25,19 +26,41 @@ uniform float pattern_length;
 
 
 #define MITER_LIMIT -0.4
+// types
+#define LINE 0
+#define CIRCLE 4
+#define RECTANGLE 5
+#define TRIANGLE 6
+
 
 vec2 screen_space(vec4 vertex)
 {
  return vec2(vertex.xy / vertex.w) * resolution;
 }
+
+// for line sections
 void emit_vertex(vec2 position, vec2 uv, int index, float ratio)
 {
  vec4 inpos = gl_in[index].gl_Position;
  f_uv = vec2((g_lastlen[index] * ratio) / pattern_length / (thickness+4) / 2.0, uv.y);
- f_color = g_color[index];
+ f_color = vec4(0, 1, 0, 1); //g_color[index];
+ gl_Position = vec4((position/resolution)*inpos.w, inpos.z, inpos.w);
+ f_id = g_id[index];
+ f_thickness = thickness;
+ f_type = LINE;
+ EmitVertex();
+}
+
+// for linecaps
+void emit_vertex(vec2 position, vec2 uv, int index, int type)
+{
+ vec4 inpos = gl_in[index].gl_Position;
+ f_uv = uv;
+ f_color = vec4(1,0,1,1);
  gl_Position = vec4((position/resolution)*inpos.w, inpos.z, inpos.w);
  f_id = g_id[index];
  f_thickness = thickness;
+ f_type = type;
  EmitVertex();
 }
 
@@ -160,8 +183,29 @@ void main(void)
  // generate the triangle strip
 
  emit_vertex(p1 + length_a * miter_a, vec2( 0, -uvy), 1, ratio);
- emit_vertex(p1 - length_a * miter_a, vec2( 0, uvy), 1, ratio);
+ emit_vertex(p1 - length_a * miter_a, vec2( 0,  uvy), 1, ratio);
 
- emit_vertex(p2 + length_b * miter_b, vec2( 0, -uvy ), 2, ratio);
- emit_vertex(p2 - length_b * miter_b, vec2( 0, uvy), 2, ratio);
+ emit_vertex(p2 + length_b * miter_b, vec2( 0, -uvy), 2, ratio);
+ emit_vertex(p2 - length_b * miter_b, vec2( 0, uvy), 2, ratio);
+
+ // generate quad for line cap
+ int cap = RECTANGLE;
+ if (cap != LINE) {
+ if (!isvalid[0] && isvalid[1]) {
+ // there is no line before this
+ EndPrimitive();
+ emit_vertex(p1 + thickness * (-v1 + n1), vec2(0.0, 0.0), 1, cap);
+ emit_vertex(p1 + thickness * (-v1 - n1), vec2(0.0, 1.0), 1, cap);
+ emit_vertex(p1 + thickness * (+ n1), vec2(0.5, 0.0), 1, cap);
+ emit_vertex(p1 + thickness * (- n1), vec2(0.5, 1.0), 1, cap);
+ }
+ if (isvalid[2] && !isvalid[3]) {
+ // there is no line after this
+ EndPrimitive();
+ emit_vertex(p2 + thickness * (+ n1), vec2(0.5, 0.0), 2, cap);
+ emit_vertex(p2 + thickness * (- n1), vec2(0.5, 1.0), 2, cap);
+ emit_vertex(p2 + thickness * (v1 + n1), vec2(1.0, 0.0), 2, cap);
+ emit_vertex(p2 + thickness * (v1 - n1), vec2(1.0, 1.0), 2, cap);
+ }
+ }
 }