mini shader (scalar field vis)

scalar field visualization with surface normals

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import java.util.Random;
import java.util.function.BiConsumer;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

import hageldave.imagingkit.core.BufferedImageFactory;
import hageldave.imagingkit.core.ImageLoader;
import hageldave.imagingkit.core.Img;
import hageldave.imagingkit.core.Pixel;

public class testmain {
	public static void main(String[] args) throws InterruptedException {
//		BiConsumer<Pixel, Long> shader = (px, time)->{
//			px.setRGB(
//				(int)(px.getXnormalized()*255)+(int)((time/10)%255), 
//				(int)(px.getYnormalized()*255), 
//				(int)(px.getYnormalized()*255));		
//			ColorSpaceTransformation.HSV_2_RGB.get().accept(px);
//		};
		BiConsumer<Pixel, Long> shader = getShader();

		Img img = new Img(256, 256); 
		BufferedImage bimg = img.getRemoteBufferedImage();
		JPanel canvas = new JPanel(){ public void paint(Graphics g) { 
			long now = System.currentTimeMillis();
			img.forEachParallel(px->{shader.accept(px, now);});
			g.drawImage(bimg, 0,0,getWidth(),getHeight(), 0,0,img.getWidth(),img.getHeight(), null);

			String shaderTime = String.format("%02dms",System.currentTimeMillis()-now);
			g.drawString(shaderTime, 2, getHeight()); g.setColor(Color.white);
			g.drawString(shaderTime, 1, getHeight()-1);
		}};
		canvas.setPreferredSize(img.getDimension());
		JFrame f = new JFrame("IMG"); f.setContentPane(canvas); 
		f.pack(); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		SwingUtilities.invokeLater(()->{f.setVisible(true);});

		final long fpsLimitTime = 1000/25; // 25fps
		long target = System.currentTimeMillis()+fpsLimitTime;
		while(true){
			long now = System.currentTimeMillis();
			canvas.repaint();
			Thread.sleep(Math.max(0, target-now));
			target = now+fpsLimitTime;
		}
	}
	
	static BiConsumer<Pixel, Long> getShader() {
		return (px, time)-> {
			int w = px.getImg().getWidth();
			int h = px.getImg().getHeight();
			float x = ((px.getX())-w/2);
			float y = ((px.getY())-h/2);
			float x1 = x+1f;
			float y1 = y;
			float x2 = x;
			float y2 = y+1f;
			
			if(true){
				float cos = (float) Math.cos(time/3000.0);
				float sin = (float) Math.sin(time/3000.0);
				float xRot = x*cos+sin*y;
				float yRot = -x*sin+cos*y;
				x = (xRot+w/2);
				y = (yRot+h/2);
				xRot = x1*cos+sin*y1;
				yRot = -x1*sin+cos*y1;
				x1 = (xRot+w/2);
				y1 = (yRot+h/2);
				xRot = x2*cos+sin*y2;
				yRot = -x2*sin+cos*y2;
				x2 = (xRot+w/2);
				y2 = (yRot+h/2);
			}
			
			float s00 = getScalar(x, y, w, h);
			float s10 = getScalar(x1, y1, w, h);
			float s01 = getScalar(x2, y2, w, h);
			
			float vecA0=1,vecA1=0,vecA2=s10-s00;// = {1,0,s10-s00};
			float vecB0=0,vecB1=1,vecB2=s01-s00;// = {0,1,s01-s00};
			// cross product
			float vecC0=vecA1*vecB2-vecB1*vecA2;
			float vecC1=vecA2*vecB0-vecB2*vecA0; 
			float vecC2=vecA0*vecB1-vecB0*vecA1;
			// normalize
			float length = (float) Math.sqrt(vecC0*vecC0+vecC1*vecC1+vecC2*vecC2);
			vecC0/=(length);
			vecC1/=(length);
			vecC2/=(length);
			
			vec2pixel(px, vecC0, vecC1, vecC2);
		};
	}
	
	static void vec2pixel(Pixel px, float v0, float v1, float v2){
//		px.setRGB_fromNormalized(v0/2+0.5f, v1/2+0.5f, v2/2+0.5f);
		float up = Math.max(0, v2);
		float right = Math.max(0, v0);
		float val = Math.min(1,up*right+up+right);
		px.setRGB_fromNormalized(val,val,val);
	}
	
	static final Img heightmap = getHeightmap();
	
	static float getScalar(float x, float y, int w, int h){
		float xf = x/(w);
		float yf = y/(h);
		return Pixel.b(heightmap.interpolateARGB(clamp(xf), clamp(yf)));
	}
	
	static float clamp(float f){
		return Math.min(1, Math.max(0, f));
	}
	
	static Img getHeightmap(){
		try {
//			URL url = new URL("https://upload.wikimedia.org/wikipedia/commons/5/57/Heightmap.png");
//			URL url = new URL("http://johnflower.org/sites/default/files/tutorial/finding-height-maps-web/lake-taupo-15m-dem.png");
			URL url = new URL("http://johnflower.org/sites/default/files/tutorial/finding-height-maps-web/mt-tarawera-15m-dem.png");
			return Img.createRemoteImg(BufferedImageFactory.getINT_ARGB(ImageLoader.loadImage(url.openStream()))); 
		} catch (IOException e) {
			e.printStackTrace();
			Random r = new Random();
			Img img = new Img(1000, 1000);
			img.forEach(px->{int val = r.nextInt(256); px.setRGB(val, val, val);});
			return img;
		}
	}
}