From 00b1e6a9bed04172ad84bdd810f1bd999e8fa0eb Mon Sep 17 00:00:00 2001
From: Pushkar Joshi
Date: Mon, 12 Mar 2012 15:02:07 -0700
Subject: bug fixes for spline interpolation

AND
Laplacian smoothing for denoising
AND
code cleanup (removing blocks of commented code)
---
 js/lib/geom/brush-stroke.js | 245 +++++++++++++++-----------------------------
 1 file changed, 81 insertions(+), 164 deletions(-)

(limited to 'js/lib')

diff --git a/js/lib/geom/brush-stroke.js b/js/lib/geom/brush-stroke.js
index a92657a4..595a6a63 100755
--- a/js/lib/geom/brush-stroke.js
+++ b/js/lib/geom/brush-stroke.js
@@ -32,7 +32,7 @@ var BrushStroke = function GLBrushStroke() {
     //stroke information
     this._strokeWidth = 0.0;
     this._strokeColor = [0.4, 0.4, 0.4, 1.0];
-    this._secondStrokeColor = this._strokeColor;
+    this._secondStrokeColor = [1, 0.4, 0.4, 1.0];
     this._strokeHardness = 100;
     this._strokeMaterial = null;
     this._strokeStyle = "Solid";
@@ -44,6 +44,12 @@ var BrushStroke = function GLBrushStroke() {
     //smaller value means more samples for the path
     this._WETNESS_FACTOR = 0.25;
 
+    //threshold that tells us whether two samples are too far apart
+    this._MAX_SAMPLE_DISTANCE_THRESHOLD = 5;
+
+    //threshold that tells us whether two samples are too close
+    this._MIN_SAMPLE_DISTANCE_THRESHOLD = 2;
+
     //prevent extremely long paths that can take a long time to render
     this._MAX_ALLOWED_SAMPLES = 500;
 
@@ -119,7 +125,7 @@ var BrushStroke = function GLBrushStroke() {
         //add the point only if it is some epsilon away from the previous point
         var numPoints = this._Points.length;
         if (numPoints>0) {
-            var threshold = 2;//this._WETNESS_FACTOR*this._strokeWidth;
+            var threshold = this._MIN_SAMPLE_DISTANCE_THRESHOLD;//this._WETNESS_FACTOR*this._strokeWidth;
             var prevPt = this._Points[numPoints-1];
             var diffPt = [prevPt[0]-pt[0], prevPt[1]-pt[1]];
             var diffPtMag = Math.sqrt(diffPt[0]*diffPt[0] + diffPt[1]*diffPt[1]);
@@ -276,13 +282,16 @@ var BrushStroke = function GLBrushStroke() {
                     }
                 }
             }
+
             //todo 4-point subdivision iterations over continuous regions of 'long' segments
             // look at http://www.gvu.gatech.edu/~jarek/Split&Tweak/ for formula
             //**** add samples to the long sections of the path --- Catmull-Rom spline interpolation
             if (this._strokeDoSmoothing && numPoints>1) {
                 var numInsertedPoints = 0;
-                var threshold = 5;//0.25*this._strokeWidth; //this determines whether a segment between two sample is too long
+                var newPoints = [];
+                var threshold = this._MAX_SAMPLE_DISTANCE_THRESHOLD;//this determines whether a segment between two sample is long enough to warrant checking for angle
                 var prevPt = this._Points[0];
+                newPoints.push(this._Points[0]);
                 for (var i=1;i<numPoints;i++){
                     var pt = this._Points[i];
                     var diff = [pt[0]-prevPt[0], pt[1]-prevPt[1]];
@@ -298,12 +307,14 @@ var BrushStroke = function GLBrushStroke() {
                             var param = (j+1)/(numNewPoints+1);
                             var newpt = this._CatmullRomSplineInterpolate(ctrlPts, param);
                             //insert new point before point i
-                            this._Points.splice(i, 0, newpt);
-                            i++;
+                            //this._Points.splice(i, 0, newpt);
+                            //i++;
+                            newPoints.push(newpt);
                             numInsertedPoints++;
                         }
                         this._dirty=true;
                     }
+                    newPoints.push(pt);
                     prevPt=pt;
                     //update numPoints to match the new length
                     numPoints = this._Points.length;
@@ -314,7 +325,22 @@ var BrushStroke = function GLBrushStroke() {
                         break;
                     }
                 }
+                this._Points = newPoints;
+                numPoints = this._Points.length;
                 console.log("Inserted "+numInsertedPoints+" additional CatmullRom points");
+
+                //now do 3-4 iterations of Laplacian smoothing (setting the points to the average of their neighbors)
+                var numLaplacianIterations = 3; //todo figure out the proper number of Laplacian iterations (perhaps as a function of stroke width)
+                for (var n=0;n<numLaplacianIterations;n++){
+                    newPoints = this._Points;
+                    for (var i=1;i<numPoints-1;i++){
+                        var avgPos = [  0.5*(this._Points[i-1][0] + this._Points[i+1][0]),
+                                        0.5*(this._Points[i-1][1] + this._Points[i+1][1]),
+                                        0.5*(this._Points[i-1][2] + this._Points[i+1][2])] ;
+                        newPoints[i] = avgPos;
+                    }
+                    this._Points = newPoints;
+                }
             }
 
             // *** compute the bounding box *********
@@ -337,11 +363,20 @@ var BrushStroke = function GLBrushStroke() {
                     }//for every dimension d from 0 to 2
                 }
             }
-             //increase the bbox given the stroke width
-            for (var d = 0; d < 3; d++) {
-                this._BBoxMin[d]-= this._strokeWidth/2;
-                this._BBoxMax[d]+= this._strokeWidth/2;
-            }//for every dimension d from 0 to 2
+
+            //increase the bbox given the stroke width and the angle (in case of calligraphic brush)
+            var bboxPadding = this._strokeWidth/2;
+            if (this.__strokeUseCalligraphic) {
+                this._BBoxMin[0]-= bboxPadding*Math.cos(this._strokeAngle);
+                this._BBoxMin[1]-= bboxPadding*Math.sin(this._strokeAngle);
+                this._BBoxMax[0]+= bboxPadding*Math.cos(this._strokeAngle);
+                this._BBoxMax[1]+= bboxPadding*Math.sin(this._strokeAngle);
+            } else {
+                for (var d = 0; d < 3; d++) {
+                    this._BBoxMin[d]-= bboxPadding;
+                    this._BBoxMax[d]+= bboxPadding;
+                }//for every dimension d from 0 to 2
+            }
         }
         this._dirty = false;
     };
@@ -375,183 +410,66 @@ var BrushStroke = function GLBrushStroke() {
         var bboxHeight = bboxMax[1] - bboxMin[1];
         ctx.clearRect(0, 0, bboxWidth, bboxHeight);
 
-        /*
-        ctx.lineWidth = this._strokeWidth;
-        ctx.strokeStyle = "black";
-        if (this._strokeColor)
-            ctx.strokeStyle = MathUtils.colorToHex( this._strokeColor );
-        ctx.fillStyle = "blue";
-        if (this._fillColor)
-            ctx.fillStyle = MathUtils.colorToHex( this._fillColor );
-        var lineCap = ['butt','round','square'];
-        ctx.lineCap = lineCap[1];
-        ctx.beginPath();
-        var firstPoint = this._Points[0];
-        ctx.moveTo(firstPoint[0]-bboxMin[0], firstPoint[1]-bboxMin[1]);
-        for (var i = 1; i < numPoints; i++) {
-            var pt = this._Points[i];
-            ctx.lineTo(pt[0]-bboxMin[0], pt[1]-bboxMin[1]);
-        }
-        ctx.stroke();
-        */
-
-        /*
-        var isDebug = false;
-        var prevPt = this._Points[0];
-        var prevX = prevPt[0]-bboxMin[0];
-        var prevY = prevPt[1]-bboxMin[1];
-        prevPt = [prevX,prevY];
-        for (var i = 1; i < numPoints; i++) {
-            var pt = this._Points[i];
-            ctx.globalCompositeOperation = 'source-over';
-            var x = pt[0]-bboxMin[0];
-            var y = pt[1]-bboxMin[1];
-            pt = [x,y];
-
-            //vector from prev to current pt
-            var seg = VecUtils.vecSubtract(2, pt, prevPt);
-            var segDir = VecUtils.vecNormalize(2, seg, 1.0);
-
-            var segMidPt = VecUtils.vecInterpolate(2, pt, prevPt, 0.5);
-            var w2 = this._strokeWidth*0.5;
-            var segDirOrtho = [w2*segDir[1], -w2*segDir[0]];
-            
-            //add half the strokewidth to the segMidPt
-            var lgStart = VecUtils.vecAdd(2, segMidPt, segDirOrtho);
-            var lgEnd = VecUtils.vecSubtract(2, segMidPt, segDirOrtho);
-
-            ctx.save();
-            ctx.beginPath();
-
-            if (isDebug) {
-                ctx.strokeStyle="black";
-                ctx.lineWidth = 1;
-
-                ctx.moveTo(lgStart[0], lgStart[1]);
-                ctx.lineTo(lgEnd[0], lgEnd[1]);
-                ctx.stroke();
-            }
-
-            var lg = ctx.createLinearGradient(lgStart[0], lgStart[1], lgEnd[0], lgEnd[1]);
-            lg.addColorStop(1, 'rgba(0,0,0,0.0)');
-            lg.addColorStop(0.5,'rgba(255,0,0,1.0)');
-            lg.addColorStop(0, 'rgba(0,0,0,0.0)');
-            ctx.fillStyle = lg;
-
-            if (isDebug){
-                ctx.strokeStyle="blue";
-                ctx.lineWidth=0.5;
-            }
-            ctx.moveTo(prevX-w2, prevY);
-            ctx.lineTo(prevX+w2, prevY);
-            ctx.lineTo(x+w2, y);
-            ctx.lineTo(x-w2, y);
-            ctx.lineTo(prevX-w2, prevY);
-            ctx.fill();
-            ctx.closePath();
-
-            ctx.restore();
-
-            prevPt = pt;
-            prevX = x;
-            prevY = y;
-        }
-        
-
-        if (isDebug)
-            ctx.stroke();
-
-        if (isDebug){
-            //draw the skeleton of this stroke
-            ctx.lineWidth = 1;
-            ctx.strokeStyle = "black";
-            var pt = this._Points[0];
-            ctx.beginPath();
-            ctx.moveTo(pt[0]-bboxMin[0],pt[1]-bboxMin[1]);
-            for (var i = 1; i < numPoints; i++) {
-                pt = this._Points[i];
-                var x = pt[0]-bboxMin[0];
-                var y = pt[1]-bboxMin[1];
-                ctx.lineTo(x,y);
-            }
-            ctx.stroke();
-        }
-        */
-
-        /*
-        var R2 = this._strokeWidth;
-        var R = R2*0.5;
-        var hardness = 0; //for a pencil, this is always 1 //TODO get hardness parameter from user interface
-        var innerRadius = (hardness*R)-1;
-        if (innerRadius<1)
-            innerRadius=1;
-
-        var r = ctx.createRadialGradient(0,0,innerRadius, 0,0,R);
-        var midColor = "rgba("+parseInt(255*this._strokeColor[0])+","+parseInt(255*this._strokeColor[1])+","+parseInt(255*this._strokeColor[2])+",1)";
-        r.addColorStop(0, midColor);
-        var endColor = "rgba("+parseInt(255*this._strokeColor[0])+","+parseInt(255*this._strokeColor[1])+","+parseInt(255*this._strokeColor[2])+",0.0)";
-        r.addColorStop(1, endColor);
-        ctx.fillStyle = r;
-
-        for (var i = 0; i < numPoints; i++) {
-            var pt = this._Points[i];
-            ctx.globalCompositeOperation = 'source-over';
-            var x = pt[0]-bboxMin[0];
-            var y = pt[1]-bboxMin[1];
-            ctx.save();
-            ctx.translate(x,y);
-            ctx.arc(0, 0, R, 0, 2 * Math.PI, false);
-            ctx.fill();
-            ctx.restore();
-            //ctx.globalCompositeOperation = 'source-in';
-            //ctx.rect(x-R, y-R, R2, R2);
-        }
-        */
-
-
         if (this._strokeUseCalligraphic) {
             //build the stamp for the brush stroke
             var t=0;
             var numTraces = this._strokeWidth;
             var halfNumTraces = numTraces/2;
-            var opaqueRegionHalfWidth = 0.5*this._strokeHardness*numTraces*0.01;
+            var opaqueRegionHalfWidth = 0.5*this._strokeHardness*numTraces*0.01; //the 0.01 is to convert the strokeHardness from [0,100] to [0,1]
             var maxTransparentRegionHalfWidth = halfNumTraces-opaqueRegionHalfWidth;
-            var startPos = [-this._strokeWidth/2,0];
-            var brushStamp = [];
 
             //build an angled (calligraphic) brush stamp
             var deltaDisplacement = [Math.cos(this._strokeAngle),Math.sin(this._strokeAngle)];
             deltaDisplacement = VecUtils.vecNormalize(2, deltaDisplacement, 1);
+            var startPos = [-halfNumTraces*deltaDisplacement[0],-halfNumTraces*deltaDisplacement[1]];
 
-            for (t=0;t<numTraces;t++){
+            var brushStamp = [];
+            /*for (t=0;t<numTraces;t++){
                 var brushPt = [startPos[0]+t*deltaDisplacement[0], startPos[1]+t*deltaDisplacement[1]];
                 brushStamp.push(brushPt);
+            }*/
+            //todo BEGIN TEMP
+            numTraces *=2;
+            halfNumTraces *= 2;
+            opaqueRegionHalfWidth *=2;
+            maxTransparentRegionHalfWidth *= 2;
+            for (t=0;t<numTraces;t++){
+                var brushPt = [startPos[0]+t*deltaDisplacement[0]*0.5, startPos[1]+t*deltaDisplacement[1]*0.5];
+                brushStamp.push(brushPt);
             }
+            //todo END TEMP
+
+            ctx.lineJoin="bevel";
+            ctx.lineCap="butt";
+            ctx.globalCompositeOperation = 'source-over';
+            //if (maxTransparentRegionHalfWidth===0){
+                ctx.globalCompositeOperation ='lighter'; //todo...we wish to add up the colors, but 'lighter' seems to produce white pixels unlike the round brush
+            //}
+            ctx.globalAlpha = this._strokeColor[3];
+            ctx.lineWidth=this._strokeWidth/10;//todo figure out the correct formula for the line width
+            //if (ctx.lineWidth<2)
+                ctx.lineWidth=1;
+            //if (t===numTraces-1){
+            //    ctx.lineWidth = 1;
+            //}
 
             for (t=0;t<numTraces;t++){
                 var disp = [brushStamp[t][0], brushStamp[t][1]];
-                //ctx.globalCompositeOperation = 'source-over';
                 var alphaVal = 1.0;
                 var distFromOpaqueRegion = Math.abs(t-halfNumTraces) - opaqueRegionHalfWidth;
                 if (distFromOpaqueRegion>0) {
                     alphaVal = 1.0 - distFromOpaqueRegion/maxTransparentRegionHalfWidth;
+                    alphaVal *= 1.0/ctx.lineWidth; //factor that accounts for lineWidth !== 1
                 }
 
                 ctx.save();
-                ctx.lineWidth=this._strokeWidth/10;//todo figure out the correct formula for the line width
-                if (ctx.lineWidth<2)
-                    ctx.lineWidth=2;
-                if (t===numTraces-1){
-                    ctx.lineWidth = 1;
-                }
-                ctx.lineJoin="bevel";
-                ctx.lineCap="butt";
-                ctx.globalAlpha = this._strokeColor[3];
-                
-                //if (t<numTraces/2)
-                    ctx.strokeStyle="rgba("+parseInt(255*this._strokeColor[0])+","+parseInt(255*this._strokeColor[1])+","+parseInt(255*this._strokeColor[2])+","+alphaVal+")";
-                //else
-                //    ctx.strokeStyle="rgba("+parseInt(255*this._secondStrokeColor[0])+","+parseInt(255*this._secondStrokeColor[1])+","+parseInt(255*this._secondStrokeColor[2])+","+alphaVal+")";
+
+                ctx.strokeStyle="rgba("+parseInt(255*this._strokeColor[0])+","+parseInt(255*this._strokeColor[1])+","+parseInt(255*this._strokeColor[2])+","+alphaVal+")";
+                //linearly interpolate between the two stroke colors
+                var currStrokeColor = VecUtils.vecInterpolate(4, this._strokeColor, this._secondStrokeColor, t/numTraces);
+                //ctx.globalAlpha = currStrokeColor[3];
+                //ctx.strokeStyle="rgba("+parseInt(255*currStrokeColor[0])+","+parseInt(255*currStrokeColor[1])+","+parseInt(255*currStrokeColor[2])+","+alphaVal+")";
+
                 ctx.translate(disp[0],disp[1]);
                 ctx.beginPath();
                 ctx.moveTo(this._Points[0][0]-bboxMin[0], this._Points[0][1]-bboxMin[1]);
@@ -562,7 +480,6 @@ var BrushStroke = function GLBrushStroke() {
                 ctx.restore();
             }
         } else {
-
             ctx.globalCompositeOperation = 'lighter'; //we wish to add up the colors
             ctx.globalAlpha = this._strokeColor[3];
             ctx.lineCap = "round";
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