First working draft of pressure hanlding

README.md

@@ -13,6 +13,7 @@ Release:
         + GC stalls!!!
         + 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 
     - Debug
         - Restore ability to limit event range
     * Listeners/events/multiplayer
@@ -40,16 +41,20 @@ Release:
         - Show what's happening while the desk is loading (downloading, processing, uploading to gpu)
         - Settings panel for config values (including the setting for "offline mode")
         - Set up VAOs
+        - We are calling "geometry_prepare_stroke" twice for some reason
     - Presentation / "marketing"
         - Title
         - Icon
         - Product page (github readme, demo videos)
 
 Bonus:
-    - Handle pressure
+    * Handle pressure
-        - Add pressure data to quads
+        + Add pressure data to quads
-        - Draw capsules instead of segments
+        + Account for pressure in quad/bbox calc
-        - Adjust curve simplification to include pressure info
+        * Adjust curve simplification to include pressure info
+        - Migrate old non-pressure desks
+        - Check out e.pressure on touch devices
+        - Send pressure in PREDRAW event
     - Curve modification
         - Select curves (with a lasso?)
         - Move whole curve

client/aux.js

@@ -64,7 +64,8 @@ function event_size(event) {
         }
 
         case EVENT.STROKE: {
-            size += 4 + 2 + 2 + 4 + event.points.length * 4 * 2; // u32 stroke id + u16 (count) + u16 (width) + u32 (color + count * (f32, f32) points
+            // u32 stroke id + u16 (count) + u16 (width) + u32 (color) + count * (f32, f32) points + count (u8) pressures
+            size += 4 + 2 + 2 + 4 + event.points.length * 4 * 2 + round_to_pow2(event.points.length, 4);
             break;
         }
 

client/client_recv.js

@@ -51,6 +51,12 @@ function des_f32array(d, count) {
     return result;
 }
 
+function des_u8array(d, count) {
+    const result = new Uint8Array(d.buffer, d.offset, count);
+    d.offset += count;
+    return result;
+}
+
 function des_event(d, state = null) {
     const event = {};
 
@@ -100,10 +106,14 @@ function des_event(d, state = null) {
             const color = des_u32(d);
 
             const coords = des_f32array(d, point_count * 2);
-            
+            const press = des_u8array(d, point_count);
+
+            des_align(d, 4);
+
             wasm_ensure_by(state, 1, coords.length);
            
             const coordinates = state.wasm.buffers['coordinates'];
+            const pressures = state.wasm.buffers['pressures'];
 
             tv_add(state.wasm.buffers['coords_from'].tv, coordinates.tv.size + point_count * 2);
             state.wasm.buffers['coords_from'].used += 4; // 4 bytes, not 4 ints
@@ -115,6 +125,9 @@ function des_event(d, state = null) {
             tv_append(coordinates.tv, coords);
             state.wasm.buffers['coordinates'].used += point_count * 2 * 4;
 
+            tv_append(pressures.tv, press);
+            state.wasm.buffers['pressures'].used += point_count;
+
             event.stroke_id = stroke_id;
 
             event.color = color;
@@ -187,7 +200,7 @@ function handle_event(state, context, event, options = {}) {
         }
 
         case EVENT.PREDRAW: {
-            geometry_add_point(state, context, event.user_id, {'x': event.x, 'y': event.y});
+            geometry_add_point(state, context, event.user_id, {'x': event.x, 'y': event.y}, 0.5); // TODO: event.pressure
             need_draw = true;
             break;
         }

client/client_send.js

@@ -43,6 +43,11 @@ function ser_clear(s) {
     s.gpu_upload_from = 0;
 }
 
+function ser_u8(s, value) {
+    s.view.setUint8(s.offset, value);
+    s.offset += 1;
+}
+
 function ser_u16(s, value) {
     s.view.setUint16(s.offset, value, true);
     s.offset += 2;
@@ -114,6 +119,12 @@ function ser_event(s, event) {
                 ser_f32(s, point.y);
             }
 
+            for (const point of event.points) {
+                ser_u8(s, point.pressure);
+            }
+
+            ser_align(s, 4);
+
             break;
         }
 

client/index.js

@@ -14,7 +14,7 @@ const config = {
     buffer_first_touchmoves: 5,
     debug_print: false,
     min_zoom: 0.00001,
-    max_zoom: 1,
+    max_zoom: 10,
     initial_offline_timeout: 1000,
     default_color: 0x00,
     default_width: 8,
@@ -237,8 +237,10 @@ async function main() {
 
         'instance_data_points': tv_create(Float32Array, 4096),
         'instance_data_ids': tv_create(Uint32Array, 4096),
+        'instance_data_pressures': tv_create(Uint8Array, 4096),
        
         'dynamic_instance_points': tv_create(Float32Array, 4096),
+        'dynamic_instance_pressure': tv_create(Uint8Array, 4096),
         'dynamic_instance_ids': tv_create(Uint32Array, 4096),
         
         'stroke_data': serializer_create(config.initial_static_bytes),

client/math.js

@@ -251,8 +251,7 @@ function segment_interesects_quad(a, b, quad_topleft, quad_bottomright, quad_top
 }
 
 function stroke_bbox(state, stroke) {
-    const radius = stroke.width / 2;
+    const radius = stroke.width; // do not divide by 2 to account for max possible pressure
-
     const coordinates = state.wasm.buffers['coordinates'].tv.data;
 
     let min_x = coordinates[stroke.coords_from + 0] - radius;

client/speed.js

@@ -19,6 +19,10 @@ async function init_wasm(state) {
             'offset': state.wasm.exports.alloc_static(state.wasm.stroke_bytes),
             'used': 0,
         },
+        'pressures': {
+            'offset': state.wasm.exports.alloc_static(state.wasm.coords_bytes / 8),
+            'used': 0
+        },
     };
 
     const mem = state.wasm.exports.memory.buffer;
@@ -29,7 +33,8 @@ async function init_wasm(state) {
         mem, state.wasm.buffers['coords_from'].offset);
     state.wasm.buffers['line_threshold'].tv = tv_create_on(Float32Array, state.wasm.stroke_bytes / 4, 
         mem, state.wasm.buffers['line_threshold'].offset);
-
+    state.wasm.buffers['pressures'].tv = tv_create_on(Uint8Array, state.wasm.coords_bytes / 8, 
+        mem, state.wasm.buffers['pressures'].offset);
 
     tv_add(state.wasm.buffers['coords_from'].tv, 0);
     state.wasm.buffers['coords_from'].used = 4;
@@ -40,6 +45,7 @@ function wasm_ensure_by(state, nstrokes, ncoords) {
 
     const old_coords_from_offset = buffers['coords_from'].offset;
     const old_line_threshold_offset = buffers['line_threshold'].offset;
+    const old_pressures_offset = buffers['pressures'].offset;
 
     const old_size_coords = state.wasm.coords_bytes;
     const old_size_strokes = state.wasm.stroke_bytes;
@@ -67,23 +73,29 @@ function wasm_ensure_by(state, nstrokes, ncoords) {
         buffers['coordinates'].offset = state.wasm.exports.alloc_static(state.wasm.coords_bytes);
         buffers['coords_from'].offset = state.wasm.exports.alloc_static(state.wasm.stroke_bytes);
         buffers['line_threshold'].offset = state.wasm.exports.alloc_static(state.wasm.stroke_bytes);
+        buffers['pressures'].offset = state.wasm.exports.alloc_static(state.wasm.coords_bytes / 8);
   
         buffers['coordinates'].tv = tv_create_on(Float32Array, state.wasm.coords_bytes / 4, mem, buffers['coordinates'].offset);
         buffers['coords_from'].tv = tv_create_on(Uint32Array, state.wasm.stroke_bytes / 4, mem, buffers['coords_from'].offset);
         buffers['line_threshold'].tv = tv_create_on(Float32Array, state.wasm.stroke_bytes / 4, mem, buffers['line_threshold'].offset);
+        buffers['pressures'].tv = tv_create_on(Uint8Array, state.wasm.coords_bytes / 8, mem, buffers['pressures'].offset);
 
         buffers['coordinates'].tv.size = buffers['coordinates'].used / 4;
         buffers['coords_from'].tv.size = buffers['coords_from'].used / 4;
         buffers['line_threshold'].tv.size = buffers['line_threshold'].used / 4;
+        buffers['pressures'].tv.size = buffers['pressures'].used;
+
+        const tmp = new Uint8Array(Math.max(state.wasm.coords_bytes / 8, state.wasm.stroke_bytes)); // TODO: needed?
 
-        const tmp = new Uint8Array(state.wasm.stroke_bytes); // TODO: needed?
+        // Copy from back to front (otherwise we will overwrite)
+        tmp.set(new Uint8Array(mem, old_pressures_offset, buffers['pressures'].used));
+        memv.set(new Uint8Array(tmp.buffer, 0, buffers['pressures'].used), buffers['pressures'].offset);
 
-        // First we move the line_threshold, only then coords_from (otherwise we will overwrite)
         tmp.set(new Uint8Array(mem, old_line_threshold_offset, old_size_strokes));
-        memv.set(tmp, buffers['coordinates'].offset + state.wasm.coords_bytes + state.wasm.stroke_bytes);
+        memv.set(new Uint8Array(tmp.buffer, 0, old_size_strokes), buffers['line_threshold'].offset);
     
         tmp.set(new Uint8Array(mem, old_coords_from_offset, old_size_strokes));
-        memv.set(tmp, buffers['coordinates'].offset + state.wasm.coords_bytes);
+        memv.set(new Uint8Array(tmp.buffer, 0, old_size_strokes), buffers['coords_from'].offset);
     }
 }
 
@@ -102,6 +114,7 @@ function do_lod_wasm(state, context) {
         buffers['coords_from'].offset,
         buffers['line_threshold'].offset,
         buffers['coordinates'].offset,
+        buffers['pressures'].offset,
         buffers['coordinates'].used / 4,
     );
 
@@ -113,13 +126,18 @@ function do_lod_wasm(state, context) {
         result_offset, segment_count * 2);
     const wasm_ids = new Uint32Array(state.wasm.exports.memory.buffer, 
         result_offset + segment_count * 2 * 4, segment_count);
-    
+    const wasm_pressures = new Uint8Array(state.wasm.exports.memory.buffer,
+        result_offset + segment_count * 2 * 4 + segment_count * 4, segment_count);
+
     context.instance_data_points.data = wasm_points;
     context.instance_data_points.size = segment_count * 2;
 
     context.instance_data_ids.data = wasm_ids;
     context.instance_data_ids.size = segment_count;
 
+    context.instance_data_pressures.data = wasm_pressures;
+    context.instance_data_pressures.size = segment_count;
+
     return segment_count;
 }
 

client/wasm/lod.c

@@ -75,6 +75,7 @@ do_lod(int *clipped_indices, int clipped_count, float zoom,
        int *stroke_coords_from,
        float *line_threshold, 
        float *coordinates,
+       unsigned char *pressures,
        int coordinates_count)
 {
     if (clipped_count == 0) {
@@ -154,6 +155,7 @@ do_lod(int *clipped_indices, int clipped_count, float zoom,
     // Write actual coordinates (points) and stroke ids
     float *points = alloc_dynamic(segments_head * 2 * 4);
     int *ids = alloc_dynamic(segments_head * 4);
+    unsigned char *pressures_res = alloc_dynamic(segments_head);
 
     int phead = 0;
     int ihead = 0;
@@ -174,6 +176,8 @@ do_lod(int *clipped_indices, int clipped_count, float zoom,
             points[phead++] = x;
             points[phead++] = y;
 
+            pressures_res[ihead] = pressures[base_stroke / 2 + point_index];
+
             if (j != to - 1) {
                 ids[ihead++] = stroke_index;
             } else {

client/webgl_draw.js

@@ -107,10 +107,16 @@ function draw(state, context) {
 
     // "Static" data upload
     if (segment_count > 0) {
+        const total_static_size = context.instance_data_points.size * 4 +
+            context.instance_data_ids.size * 4 +
+            context.instance_data_pressures.size;
+
         gl.bindBuffer(gl.ARRAY_BUFFER, buffers['b_instance']);
-        gl.bufferData(gl.ARRAY_BUFFER, context.instance_data_points.size * 4 + context.instance_data_ids.size * 4, gl.STREAM_DRAW);
+        gl.bufferData(gl.ARRAY_BUFFER, total_static_size, gl.STREAM_DRAW);
         gl.bufferSubData(gl.ARRAY_BUFFER, 0, tv_data(context.instance_data_points)); 
         gl.bufferSubData(gl.ARRAY_BUFFER, context.instance_data_points.size * 4, tv_data(context.instance_data_ids));
+        gl.bufferSubData(gl.ARRAY_BUFFER, context.instance_data_points.size * 4 + context.instance_data_ids.size * 4,
+            tv_data(context.instance_data_pressures));
         gl.bindTexture(gl.TEXTURE_2D, context.textures['stroke_data']);
         upload_square_rgba16ui_texture(gl, context.stroke_data, config.stroke_texture_size);
 
@@ -125,15 +131,18 @@ function draw(state, context) {
         gl.enableVertexAttribArray(locations['a_a']);
         gl.enableVertexAttribArray(locations['a_b']);
         gl.enableVertexAttribArray(locations['a_stroke_id']);
+        gl.enableVertexAttribArray(locations['a_pressure']);
 
         // Points (a, b) and stroke ids are stored in separate cpu buffers so that points can be reused (look at stride and offset values)
         gl.vertexAttribPointer(locations['a_a'],          2, gl.FLOAT,         false, 2 * 4, 0);
         gl.vertexAttribPointer(locations['a_b'],          2, gl.FLOAT,         false, 2 * 4, 2 * 4);
         gl.vertexAttribIPointer(locations['a_stroke_id'], 1, gl.INT,                  4, context.instance_data_points.size * 4);
+        gl.vertexAttribPointer(locations['a_pressure'],   1, gl.UNSIGNED_BYTE, true,  1, context.instance_data_points.size * 4 + context.instance_data_ids.size * 4);
 
         gl.vertexAttribDivisor(locations['a_a'], 1);
         gl.vertexAttribDivisor(locations['a_b'], 1);
         gl.vertexAttribDivisor(locations['a_stroke_id'], 1);
+        gl.vertexAttribDivisor(locations['a_pressure'], 1);
 
         // Static draw (everything already bound)
         gl.drawArraysInstanced(gl.TRIANGLES, 0, 6, segment_count); 
@@ -151,24 +160,33 @@ function draw(state, context) {
         gl.bindBuffer(gl.ARRAY_BUFFER, buffers['b_dynamic_instance']);
 
         // Dynamic data upload
-        gl.bufferData(gl.ARRAY_BUFFER, context.dynamic_instance_points.size * 4 + context.dynamic_instance_ids.size * 4, gl.STREAM_DRAW);
+        const total_dynamic_size = 
+            context.dynamic_instance_points.size * 4 + context.dynamic_instance_ids.size * 4 + 
+            context.dynamic_instance_pressure.size;
+
+        gl.bufferData(gl.ARRAY_BUFFER, total_dynamic_size, gl.STREAM_DRAW);
         gl.bufferSubData(gl.ARRAY_BUFFER, 0, tv_data(context.dynamic_instance_points)); 
         gl.bufferSubData(gl.ARRAY_BUFFER, context.dynamic_instance_points.size * 4, tv_data(context.dynamic_instance_ids));
+        gl.bufferSubData(gl.ARRAY_BUFFER, context.dynamic_instance_points.size * 4 + context.dynamic_instance_ids.size * 4, 
+            tv_data(context.dynamic_instance_pressure));
         gl.bindTexture(gl.TEXTURE_2D, context.textures['dynamic_stroke_data']);
         upload_square_rgba16ui_texture(gl, context.dynamic_stroke_data, config.dynamic_stroke_texture_size);
 
         gl.enableVertexAttribArray(locations['a_a']);
         gl.enableVertexAttribArray(locations['a_b']);
         gl.enableVertexAttribArray(locations['a_stroke_id']);
+        gl.enableVertexAttribArray(locations['a_pressure']);
 
         // Points (a, b) and stroke ids are stored in separate cpu buffers so that points can be reused (look at stride and offset values)
         gl.vertexAttribPointer(locations['a_a'],          2, gl.FLOAT,         false, 2 * 4, 0);
         gl.vertexAttribPointer(locations['a_b'],          2, gl.FLOAT,         false, 2 * 4, 2 * 4);
         gl.vertexAttribIPointer(locations['a_stroke_id'], 1, gl.INT,                  4, context.dynamic_instance_points.size * 4);
+        gl.vertexAttribPointer(locations['a_pressure'],   1, gl.UNSIGNED_BYTE, true,  1, context.dynamic_instance_points.size * 4 + context.dynamic_instance_ids.size * 4);
 
         gl.vertexAttribDivisor(locations['a_a'], 1);
         gl.vertexAttribDivisor(locations['a_b'], 1);
         gl.vertexAttribDivisor(locations['a_stroke_id'], 1);
+        gl.vertexAttribDivisor(locations['a_pressure'], 1);
 
         gl.drawArraysInstanced(gl.TRIANGLES, 0, 6, dynamic_segment_count);
     }

client/webgl_geometry.js

@@ -105,9 +105,11 @@ function recompute_dynamic_data(state, context) {
     }
 
     tv_ensure(context.dynamic_instance_points, round_to_pow2(total_points * 2, 4096));
+    tv_ensure(context.dynamic_instance_pressure, round_to_pow2(total_points, 4096));
     tv_ensure(context.dynamic_instance_ids, round_to_pow2(total_points, 4096));
 
     tv_clear(context.dynamic_instance_points);
+    tv_clear(context.dynamic_instance_pressure);
     tv_clear(context.dynamic_instance_ids);
     
     context.dynamic_stroke_data = ser_ensure(context.dynamic_stroke_data, config.bytes_per_stroke * total_strokes);
@@ -124,6 +126,7 @@ function recompute_dynamic_data(state, context) {
 
             tv_add(context.dynamic_instance_points, p.x);
             tv_add(context.dynamic_instance_points, p.y);
+            tv_add(context.dynamic_instance_pressure, p.pressure);
 
             if (i !== player.points.length - 1) {
                 tv_add(context.dynamic_instance_ids, stroke_index);

client/webgl_listeners.js

@@ -204,6 +204,7 @@ function mousedown(e, state, context) {
     }
 
     if (state.tools.active === 'pencil') {
+        canvasp.pressure = 128;
         geometry_clear_player(state, context, state.me);
         geometry_add_point(state, context, state.me, canvasp);
 
@@ -253,7 +254,7 @@ function mousemove(e, state, context) {
     }
 
     if (state.drawing) {
-        //console.log(e.pressure);
+        canvasp.pressure = Math.ceil(e.pressure * 255);
         geometry_add_point(state, context, state.me, canvasp);
         fire_event(state, predraw_event(canvasp.x, canvasp.y));
         do_draw = true;
@@ -442,7 +443,7 @@ function touchmove(e, state, context) {
             state.touch.waiting_for_second_finger = false;
         }
 
-
+        canvasp.pressure = 128; // TODO: check out touch devices' e.pressure
         geometry_add_point(state, context, state.me, canvasp);
         fire_event(state, predraw_event(canvasp.x, canvasp.y));
 

client/webgl_shaders.js

@@ -104,8 +104,8 @@ const nop_fs_src = `#version 300 es
 const sdf_vs_src = `#version 300 es
     in vec2 a_a; // point from
     in vec2 a_b; // point to
-    in float a_radius;
     in int a_stroke_id;
+    in float a_pressure;
 
     uniform vec2 u_scale;
     uniform vec2 u_res;
@@ -159,21 +159,21 @@ const sdf_vs_src = `#version 300 es
             outwards = -up_dir + line_dir;
         }
       
-        vec2 pos = origin + normalize(outwards) * radius;
+        vec2 pos = origin + normalize(outwards) * radius * 2.0; // doubling is to account for max possible pressure
         screen02 = (pos.xy * u_scale + u_translation) / u_res * 2.0 + outwards * pixel;
         v_texcoord = pos.xy + outwards * rscale;
 
         screen02.y = 2.0 - screen02.y;
 
         v_line = vec4(a_a, a_b);        
-        v_thickness = radius;
+        v_thickness = radius * a_pressure * 2.0; // pressure 0.5 is the "neutral" pressure
         v_color = vec3(stroke_data.xyz) / 255.0;
 
         if (a_stroke_id >> 31 != 0) {
             screen02 += vec2(100.0); // shift offscreen
         }
 
-        gl_Position = vec4(screen02 - 1.0, (float(a_stroke_id) / float(u_stroke_count)) * 2.0 - 1.0, 1);
+        gl_Position = vec4(screen02 - 1.0, (float(a_stroke_id) / float(u_stroke_count)) * 2.0 - 1.0, 1.0);
     }
 `;
 
@@ -312,6 +312,7 @@ function init_webgl(state, context) {
             'a_a':               gl.getAttribLocation(context.programs['sdf'].main, 'a_a'),
             'a_b':               gl.getAttribLocation(context.programs['sdf'].main, 'a_b'),
             'a_stroke_id':       gl.getAttribLocation(context.programs['sdf'].main, 'a_stroke_id'),
+            'a_pressure':        gl.getAttribLocation(context.programs['sdf'].main, 'a_pressure'),
 
             'u_res':             gl.getUniformLocation(context.programs['sdf'].main, 'u_res'),
             'u_scale':           gl.getUniformLocation(context.programs['sdf'].main, 'u_scale'),

server/deserializer.js

@@ -38,6 +38,12 @@ function f32array(d, count) {
     return array;
 }
 
+function u8array(d, count) {
+    const array = new Uint8Array(d.view.buffer, d.offset, count);
+    d.offset += count;
+    return array;
+}
+
 export function align(d, to) {
     while (d.offset % to !== 0) {
         d.offset++;
@@ -91,6 +97,8 @@ export function event(d) {
             event.width = width;
             event.color = color;
             event.points = f32array(d, point_count * 2);
+            event.pressures = u8array(d, point_count);
+            align(d, 4);
             break;
         }
 

server/math.js

@@ -8,3 +8,7 @@ export function crypto_random32() {
 
     return dataview.getUint32(0);
 }
+
+export function round_to_pow2(value, multiple) {
+    return (value + multiple - 1) & -multiple;
+}

server/recv.js

@@ -110,7 +110,8 @@ function handle_event(session, event) {
             const stroke_result = storage.queries.insert_stroke.get({
                 '$width': event.width, 
                 '$color': event.color,
-                '$points': event.points
+                '$points': event.points,
+                '$pressures': event.pressures,
             });
 
             event.stroke_id = stroke_result.id;

server/send.js

@@ -40,6 +40,7 @@ function event_size(event) {
         case EVENT.STROKE: {
             size += 4 + 2 + 2 + 4; // stroke id + point count + width + color
             size += event.points.byteLength;
+            size += math.round_to_pow2(event.pressures.byteLength, 4);
             break;
         }
 

server/serializer.js

@@ -85,11 +85,14 @@ export function event(s, event) {
 
         case EVENT.STROKE: {
             const points_bytes = event.points;
+            const pressures_bytes = event.pressures;
             u32(s, event.stroke_id);
             u16(s, points_bytes.byteLength / 2 / 4); // each point is 2 * f32
             u16(s, event.width);
             u32(s, event.color);
             bytes(s, points_bytes);
+            bytes(s, pressures_bytes);
+            align(s, 4);
             break;
         }
 

server/storage.js

@@ -38,7 +38,8 @@ export function startup() {
         id INTEGER PRIMARY KEY,
         width INTEGER,
         color INTEGER,
-        points BLOB
+        points BLOB,
+        pressures BLOB
     );`).run();
 
     db.query(`CREATE TABLE IF NOT EXISTS events (
@@ -69,7 +70,7 @@ export function startup() {
 
     // INSERT
     queries.insert_desk    = db.query('INSERT INTO desks    (id, title, sn)                                        VALUES ($id, $title, 0) RETURNING id');
-    queries.insert_stroke  = db.query('INSERT INTO strokes  (width, color, points)                                 VALUES ($width, $color, $points) RETURNING id');
+    queries.insert_stroke  = db.query('INSERT INTO strokes  (width, color, points, pressures)                      VALUES ($width, $color, $points, $pressures) RETURNING id');
     queries.insert_session = db.query('INSERT INTO sessions (id, desk_id, lsn)                                     VALUES ($id, $desk_id, 0) RETURNING id');
     queries.insert_event   = db.query('INSERT INTO events   (type, desk_id, session_id, stroke_id, image_id, x, y) VALUES ($type, $desk_id, $session_id, $stroke_id, $image_id, $x, $y) RETURNING id');
 
@@ -115,6 +116,7 @@ export function startup() {
         if (event.type === EVENT.STROKE) {
             const stroke = stroke_dict[event.stroke_id];
             event.points = stroke.points;
+            event.pressures = stroke.pressures;
             event.color = stroke.color;
             event.width = stroke.width;