revamping fork math

docs/TODO_ux.md

@@ -66,8 +66,7 @@
 ## Switch to OpenGL (for speed)
 
 - no bugs
-	- forking is buggy (traffic signal diagram)
-	- arrows
+	- arrows... then debug legend
 	- top menu rectangles are slightly off; grab the " " glyph's width?
 	- some colors are wrong
 		- ContextBuilder has with_pixel_format and with_srgb

editor/src/plugins/view/legend.rs

@@ -42,14 +42,8 @@ impl Plugin for Legend {
     }
 
     fn draw(&self, g: &mut GfxCtx, ctx: &Ctx) {
-        // TODO The negation and reasoning about the zoom is annoying. I want to say something like
-        // "Make top_left the origin, zoom 10."
         let zoom = 10.0;
-        g.fork(
-            Pt2D::new(-self.top_left.x / zoom, -self.top_left.y / zoom),
-            zoom,
-            &ctx.canvas,
-        );
+        g.fork(Pt2D::new(0.0, 0.0), self.top_left, zoom, &ctx.canvas);
 
         // Create a fake turn.
         let mut turn = Turn {
@@ -60,6 +54,8 @@ impl Plugin for Legend {
             },
             turn_type: TurnType::Straight,
             lookup_idx: 0,
+            // TODO Do we need to zoom here at all? For the arrows, sadly. Annoying to express the
+            // fake geometry in terms of zoom, but oh well.
             geom: PolyLine::new(vec![
                 Pt2D::new(10.0 / zoom, 10.0 / zoom),
                 Pt2D::new(10.0 / zoom, 100.0 / zoom),

editor/src/render/intersection.rs

@@ -353,27 +353,15 @@ pub fn draw_signal_diagram(
     );
 
     for (idx, (txt, cycle)) in labels.into_iter().zip(cycles.iter()).enumerate() {
-        // TODO API for "make this map pt be this screen pt"
-        g.fork(
-            Pt2D::new(
-                top_left.x() - (x1_screen / zoom),
-                top_left.y()
-                    - (y1_screen / zoom)
-                    - intersection_height * (idx as f64)
-                    - padding * ((idx as f64) + 1.0),
-            ),
-            zoom,
-            &ctx.canvas,
-        );
+        let y1 = y1_screen + (padding + intersection_height) * (idx as f64) * zoom;
+
+        g.fork(top_left, ScreenPt::new(x1_screen, y1), zoom, &ctx.canvas);
         draw_signal_cycle(&cycle, g, ctx);
 
         ctx.canvas.draw_text_at_screenspace_topleft(
             g,
             txt,
-            ScreenPt::new(
-                x1_screen + 10.0 + (intersection_width * zoom),
-                y1_screen + (padding + intersection_height) * (idx as f64) * zoom,
-            ),
+            ScreenPt::new(x1_screen + 10.0 + (intersection_width * zoom), y1),
         );
     }
 

ezgui/src/lib.rs

@@ -130,15 +130,28 @@ impl<'a> GfxCtx<'a> {
     // Up to the caller to call unfork()!
     // TODO Canvas doesn't understand this change, so things like text drawing that use
     // map_to_screen will just be confusing.
-    pub fn fork(&mut self, top_left: Pt2D, zoom: f64, canvas: &Canvas) {
+    pub fn fork(
+        &mut self,
+        top_left_map: Pt2D,
+        top_left_screen: ScreenPt,
+        zoom: f64,
+        canvas: &Canvas,
+    ) {
+        // map_to_screen of top_left_map should be top_left_screen
+        let cam_x = (top_left_map.x() * zoom) - top_left_screen.x;
+        let cam_y = (top_left_map.y() * zoom) - top_left_screen.y;
+
         self.uniforms = uniform! {
-            transform: [top_left.x() as f32, top_left.y() as f32, zoom as f32],
+            transform: [cam_x as f32, cam_y as f32, zoom as f32],
             window: [canvas.window_width as f32, canvas.window_height as f32],
         };
     }
 
     pub fn fork_screenspace(&mut self, canvas: &Canvas) {
-        self.fork(Pt2D::new(0.0, 0.0), 1.0, canvas)
+        self.uniforms = uniform! {
+            transform: [0.0, 0.0, 1.0],
+            window: [canvas.window_width as f32, canvas.window_height as f32],
+        };
     }
 
     pub fn unfork(&mut self, canvas: &Canvas) {