display: Add basic stroke support

1 files changed, 20 insertions, 3 deletions

diff --git a/virtual-programs/display.folk b/virtual-programs/display.folk
index 7d4f47b6..c9c172cc 100644
--- a/virtual-programs/display.folk
+++ b/virtual-programs/display.folk
@@ -40,12 +40,29 @@ namespace eval ::Display {
 On process {
     source pi/Gpu.tcl
     Gpu::init
+    Gpu::ImageManager::imageManagerInit
 
     namespace eval Display {
-        proc start {} {}
+        variable line [Gpu::pipeline {vec2 from vec2 to float thickness} {
+            float l = length(to - from);
+            vec2 d = (to - from) / l;
+            vec2 q = (gl_FragCoord.xy - (from + to)*0.5);
+            q = mat2(d.x, -d.y, d.y, d.x) * q;
+            q = abs(q) - vec2(l, thickness)*0.5;
+            float dist = length(max(q, 0.0)) + min(max(q.x, q.y), 0.0);
+
+            return dist < 0.0 ? vec4(1, 0, 1, 1) : vec4(0, 0, 0, 0);
+        }]
 
-        proc stroke {points width color} {
+        proc start {} { Gpu::drawStart }
 
+        proc stroke {points width color} {
+            variable line
+            for {set i 0} {$i < [expr {[llength $points] - 1}]} {incr i} {
+                set from [lindex $points $i]
+                set to [lindex $points [expr $i+1]]
+                Gpu::draw $line $from $to $width
+            }
         }
         proc circle {x y radius thickness color} {}
         proc text {x y scale text radians} {}
@@ -54,7 +71,7 @@ On process {
         proc fillPolygon {args} {}
         proc image {x y im radians {scale 1.0}} {}
 
-        proc end {} {}
+        proc end {} { Gpu::drawEnd }
     }
 
     puts "Display tid: [getTid]"