blob_extraction.mm

- (void)fetchContours {
	
	int currentPixel, currentDir;
	RSPoint point, nextPoint, testPoint;
	
	lastEntryPoint = RSPointMake(0,0);
	lastPoint = RSPointMake(0,0);
	
	lastFoundDir = 4;
	marching = YES;
	connected = NO;
	
	for (int y=0; y<h; y++) {
		for (int x=0; x<w; x++) {
			
			// Is marching
			if (YES == marching) {
				
				RSContour currentPolygon;
				currentPolygon.push_back(lastEntryPoint);
				
				// Inner marching loop
				while (YES) {
					nextPoint = [self scan:lastPoint withComparator:currentPolygonColor];
					
					// Break conditions
					// Previously seen color found 4-connected or we've come full circle
					if (YES == connected || nextPoint == lastEntryPoint) {
						int pointsCount = currentPolygon.size();
						for (int i=0; i<pointsCount; i++) {
							point = currentPolygon.at(i);
							[self setPointAsSeen:point];
						}
						if (NO == connected) {
							// Add this polygon to our polygons
							contours.push_back(currentPolygon);
						}
						marching = NO;
						break;
					}
					else {
						// Add this next point to our current polygon
						currentPolygon.push_back(nextPoint);
						lastPoint = nextPoint;
					}
				}
			}
			
			// Is scanning
			else {
				currentPixel = originalImage[y * w + x];
				if (currentPixel > 0) {
					
					// We have an 'unseen' pixel, first see if we're connected to a seen area
					RSPoint thisPoint = {x,y};
					testPoint = [self scan:thisPoint withComparatorSeen:currentPixel];
					if (testPoint.x != -1) {
						// If so, set that to 'seen'
						[self setPointAsSeen:point];
					}
					else {
						// Nothing connected, start a new polygon
						lastEntryPoint = RSPointMake(x,y);
						lastPoint = RSPointMake(x,y);
						currentPolygonColor = currentPixel;
						lastFoundDir = 4;
						currentDir = -1;
						marching = YES;
						connected = NO;
					}
				}
			}
		}
	}
}