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(Extra) Curve Reactor
(Extra) Curve Reactor
This example uses a curve as the reactor object. The curve is subdivided into several points, and those points used in the similar way as the previous reactor examples.
int NDIVS = 100; // # of subdivisions, higher is more accurate, but slower, and vice versa PVector [] cps; // curve controll points int gridWidth = 30; int gridHeight = 30; float shapeWidth = 19; float shapeHeight = 19; float reactorScaler = .006; void setup() { size(500,500); smooth(); cps = new PVector[4]; for (int i=0; i<4; i++) { cps[i] = new PVector(); } cps[0].x = width+300; cps[0].y = -500; cps[1].x= 50; cps[1].y= 50; cps[2].x= width-50; cps[2].y= height-50; cps[3].x= -500; cps[3].y= height+300; } void draw() { background(255); drawGeometry(); } void drawGeometry() { stroke(255,0,0); noFill(); curve(cps[0].x,cps[0].y, cps[1].x,cps[1].y, cps[2].x,cps[2].y, cps[3].x,cps[3].y); fill(0); noStroke(); for(int i = 0; i<gridWidth; i++ ) { for(int j = 0; j<gridHeight; j++ ) { PVector myPos = new PVector(i*shapeWidth, j*shapeHeight); PVector cpt = ClosestPointOnCatmullRom(cps,myPos,NDIVS); float reactorDistance = dist(cpt.x, cpt.y, myPos.x, myPos.y); float scaler = reactorDistance*reactorScaler; //translate(posX, posY); ellipse(myPos.x, myPos.y, shapeWidth*scaler, shapeHeight*scaler); }; }; } // see http://davebollinger.org/category/code/ /** * Returns the closest point on a catmull-rom curve relative to a search location. * This is only an approximation, by subdividing the curve a given number of times. * More subdivisions gives a better approximation but takes longer, and vice versa. * No concern is given to handling multiple equidistant points on the curve - the * first encountered equidistant point on the subdivided curve is returned. * * @param cps array of four PVectors that define the control points of the curve * @param pt the search-from location * @param ndivs how many segments to subdivide the curve into * @returns PVector containing closest subdivided point on curve */ PVector ClosestPointOnCatmullRom(PVector [] cps, PVector pt, int steps) { PVector result = new PVector(); float bestDistanceSquared = 0; float bestT = 0; for (int i=0; i<=steps; i++) { float t = (float)(i) / (float)(steps); float x = curvePoint(cps[0].x,cps[1].x,cps[2].x,cps[3].x,t); float y = curvePoint(cps[0].y,cps[1].y,cps[2].y,cps[3].y,t); float dissq = dist(pt.x, pt.y, x, y); if (i==0 || dissq < bestDistanceSquared) { bestDistanceSquared = dissq; bestT = t; result.set(x,y,0); } } return result; }
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