Add line-line intersection test to the eraser to kinda make it work for faster movement

README.txt

@@ -16,7 +16,6 @@ Release:
         + Stroke previews get connected when drawn without panning on touch devices
         + Redraw HTML (cursors) on local canvas moves
         + New strokes dissapear on the HMH desk 
-        - Color picker misses on strange line endings
     - Debug
         - Restore ability to limit event range
     * Listeners/events/multiplayer
@@ -42,11 +41,12 @@ Release:
         + EYE DROPPER!
         + Dynamic svg cursor to represent the brush
         + Eraser
-        - Line drawing
+        * Line drawing
         + Undo
             - Undo for images (add, move, scale)
             - Undo for eraser
         - Redo
+        - Snapping to grid
     * Polish
         + Use typedvector where appropriate
         - Show what's happening while the desk is loading (downloading, processing, uploading to gpu)
@@ -54,7 +54,7 @@ Release:
         - Set up VAOs
         - We are calling "geometry_prepare_stroke" twice for some reason
     - Presentation / "marketing"
-        - Title (InfiNotes?)
+        - Title (InfiNotes? MegaDesk?)
         - Icon
         - Product page (github readme, demo videos)
 

client/bvh.js

@@ -164,7 +164,7 @@ function bvh_delete_stroke(state, stroke) {
     
     while (node.parent_index !== null) {
         if (node.is_fullnode) {
-            let index_index = node.stroke_indices.data.indexOf(stroke.index);
+            let index_index = tv_data(node.stroke_indices).indexOf(stroke.index);
             if (index_index !== -1) {
                 node.stroke_indices.data[index_index] = node.stroke_indices.data[node.stroke_indices.size - 1];
                 tv_pop(node.stroke_indices);

client/math.js

@@ -436,7 +436,7 @@ function circle_intersects_capsule(ax, ay, bx, by, p1, p2, cx, cy, r) {
     return dist <= r;
 }
 
-function stroke_intersects_cursor(state, stroke, canvasp, radius) {
+function stroke_intersects_capsule(state, stroke, a, b, radius) {
     const xs = state.wasm.buffers['xs'].tv.data;
     const ys = state.wasm.buffers['ys'].tv.data;
     const pressures = state.wasm.buffers['pressures'].tv.data;
@@ -449,8 +449,17 @@ function stroke_intersects_cursor(state, stroke, canvasp, radius) {
         const p1 = pressures[i + 0];
         const p2 = pressures[i + 1];
 
+        // Test if p1 or p2 overlap the capsule
+        if (circle_intersects_capsule(x1, y1, x2, y2, p1 * stroke.width / 255, p2 * stroke.width / 255, a.x, a.y, radius)) {
+            return true;
+        }
+        if (circle_intersects_capsule(x1, y1, x2, y2, p1 * stroke.width / 255, p2 * stroke.width / 255, b.x, b.y, radius)) {
+            return true;
+        }
 
-        if (circle_intersects_capsule(x1, y1, x2, y2, p1 * stroke.width / 255, p2 * stroke.width / 255, canvasp.x, canvasp.y, radius)) {
+        // Lame test for the quad part, only test for line-line intersection
+        // TODO: actually test for rotated quad vs circle/rotated quad overlap
+        if (segments_intersect(a, b, {'x': x1, 'y': y1}, {'x': x2, 'y': y2})) {
             return true;
         }
     }

client/webgl_listeners.js

@@ -383,23 +383,27 @@ function mousemove(e, state, context) {
     if (state.erasing) {
         const me = state.players[state.me];
         const radius = Math.round(me.width / 2);
+        const last_canvasp = screen_to_canvas(state, state.cursor); 
 
         const cursor_bbox = {
-            'x1': canvasp.x - radius,
+            'x1': Math.min(canvasp.x, last_canvasp.x) - radius,
-            'y1': canvasp.y - radius,
+            'y1': Math.min(canvasp.y, last_canvasp.y) - radius,
-            'x2': canvasp.x + radius,
+            'x2': Math.max(canvasp.x, last_canvasp.x) + radius,
-            'y2': canvasp.y + radius,
+            'y2': Math.max(canvasp.y, last_canvasp.y) + radius,
         };
 
         tv_ensure(state.erase_candidates, round_to_pow2(state.stroke_count, 4096));
         tv_clear(state.erase_candidates);
+
+        // Rough pass, not all of these might actually need to be erased
         bvh_intersect_quad(state, state.bvh, cursor_bbox, state.erase_candidates);
 
+        // Fine pass, actually run expensive capsule vs capsule intersection tests
         for (let i = 0; i < state.erase_candidates.size; ++i) {
             const stroke_id = state.erase_candidates.data[i];
             const stroke = state.events[stroke_id];
 
-            if (!stroke.deleted && stroke_intersects_cursor(state, stroke, canvasp, radius)) {
+            if (!stroke.deleted && stroke_intersects_capsule(state, stroke, last_canvasp, canvasp, radius)) {
                 stroke.deleted = true;
                 bvh_delete_stroke(state, stroke);
                 queue_event(state, eraser_event(stroke_id));