Faster clipping

client/index.js

@@ -173,6 +173,7 @@ function main() {
         },
 
         'players': {},
+        'onscreen_segments': [],
     };
 
     const context = {

client/math.js

@@ -207,8 +207,19 @@ function quad_onscreen(screen, bbox) {
     return false;
 }
 
+function quad_fully_onscreen(screen, bbox) {
+    if (screen.x1 < bbox.x1 && screen.x2 > bbox.x2 && screen.y1 < bbox.y1 && screen.y2 > bbox.y2) {
+        return true;
+    }
+
+    return false;
+}
+
 function segments_onscreen(state, context) {
-    const result = [];
+    // TODO: handle stroke width
+
+    state.onscreen_segments.length = 0;
+
     const screen_topleft = screen_to_canvas(state, {'x': 0, 'y': 0});
     const screen_bottomright = screen_to_canvas(state, {'x': context.canvas.width, 'y': context.canvas.height});
     const screen_topright = { 'x': screen_bottomright.x, 'y': screen_topleft.y };
@@ -221,21 +232,20 @@ function segments_onscreen(state, context) {
         const event = state.events[i];
         if (event.type === EVENT.STROKE && !event.deleted) {
             if (quad_onscreen(screen, event.bbox)) {
+                const fully_onscreen = quad_fully_onscreen(screen, event.bbox);
                 for (let j = 0; j < event.points.length - 1; ++j) {
                     const a = event.points[j + 0];
                     const b = event.points[j + 1];
 
-                    if (segment_interesects_quad(a, b, screen_topleft, screen_bottomright, screen_topright, screen_bottomleft)) {
+                    if (fully_onscreen || segment_interesects_quad(a, b, screen_topleft, screen_bottomright, screen_topright, screen_bottomleft)) {
                         let base = head + j * 4;
                         // We draw quads as [1, 2, 3, 4, 3, 2]
-                        result.push(base + 0, base + 1, base + 2);
-                        result.push(base + 3, base + 2, base + 1);
+                        state.onscreen_segments.push(base + 0, base + 1, base + 2);
+                        state.onscreen_segments.push(base + 3, base + 2, base + 1);
                     }
                 }
             }
             head += (event.points.length - 1) * 4;
         }
     }
-
-    return result;
 }

client/webgl_draw.js

@@ -11,9 +11,13 @@ function draw(state, context) {
     const gl = context.gl;
     const width = window.innerWidth;
     const height = window.innerHeight;
+    
+    let query = null;
 
-    const frame_start = performance.now();
-    const sync = gl.fenceSync(gl.SYNC_GPU_COMMANDS_COMPLETE, 0);
+    if (context.gpu_timer_ext !== null) {
+        query = gl.createQuery();
+        gl.beginQuery(context.gpu_timer_ext.TIME_ELAPSED_EXT, query);
+    }
 
     let locations;
     let buffers;
@@ -64,11 +68,17 @@ function draw(state, context) {
             context.static_upload_from = context.static_serializer.offset;
         }
 
-        const indices = segments_onscreen(state, context); 
+        const before_clip = performance.now();
+        segments_onscreen(state, context); 
+        const after_clip = performance.now();
+        console.debug('clip', after_clip - before_clip);
 
         gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, buffers['b_packed_static_index']);
-        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint32Array(indices), gl.DYNAMIC_DRAW);
-        gl.drawElements(gl.TRIANGLES, indices.length, gl.UNSIGNED_INT, 0);
+        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint32Array(state.onscreen_segments), gl.DYNAMIC_DRAW);
+        const after_index_uploads = performance.now();
+        console.debug('index upload', after_index_uploads - after_clip);
+
+        gl.drawElements(gl.TRIANGLES, state.onscreen_segments.length, gl.UNSIGNED_INT, 0);
     }
 
     if (dynamic_points > 0) {
@@ -89,7 +99,7 @@ function draw(state, context) {
 
         gl.drawArrays(gl.TRIANGLES, 0, dynamic_points);
     }
-
+/*
     const next_tick = () => {
         const wait_status = gl.clientWaitSync(sync, 0, 0);
         const frame_end = performance.now();
@@ -104,8 +114,36 @@ function draw(state, context) {
     }
 
     setTimeout(next_tick, 0);
+    */
+
+    if (context.gpu_timer_ext) {
+        gl.endQuery(context.gpu_timer_ext.TIME_ELAPSED_EXT);
+
+        const next_tick = () => {
+            if (query) {
+                // At some point in the future, after returning control to the browser
+                const available = gl.getQueryParameter(query, gl.QUERY_RESULT_AVAILABLE);
+                const disjoint = gl.getParameter(context.gpu_timer_ext.GPU_DISJOINT_EXT);
+
+                if (available && !disjoint) {
+                    // See how much time the rendering of the object took in nanoseconds.
+                    const timeElapsed = gl.getQueryParameter(query, gl.QUERY_RESULT);
+                    console.debug(timeElapsed / 1000000);
+                }
+
+                if (available || disjoint) {
+                    // Clean up the query object.
+                    gl.deleteQuery(query);
+                    // Don't re-enter this polling loop.
+                    query = null;
+                } else {
+                    setTimeout(next_tick, 0);
+                }
+            }
+        }
 
-
+        setTimeout(next_tick, 0);
+    }
     // Images
     // locations = context.locations['image'];
     // buffers = context.buffers['image'];

client/webgl_shaders.js

@@ -80,7 +80,7 @@ const sdf_fs_src = `#version 300 es
         // float alpha = 1.0 - step(0.0, dist);
 
         if (u_debug_mode == 1) {
-            FragColor = vec4(1.0, 0.0, 0.0, 0.5);
+            FragColor = vec4(1.0, 0.0, 0.0, 0.1);
         } else {
             FragColor = vec4(v_color * alpha, alpha);
             // FragColor = vec4(v_color * alpha, 0.1 + alpha);
@@ -140,6 +140,8 @@ function init_webgl(state, context) {
     gl.enable(gl.BLEND);
     gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
 
+    context.gpu_timer_ext = gl.getExtension('EXT_disjoint_timer_query_webgl2');
+
     const quad_vs = create_shader(gl, gl.VERTEX_SHADER, tquad_vs_src);
     const quad_fs = create_shader(gl, gl.FRAGMENT_SHADER, tquad_fs_src);