import java.applet.*; import java.awt.*; import java.io.*; import java.net.*; import java.util.*; /*************************************************** * * An instructional Ray-Tracing Renderer written * for MIT 6.837 Fall '98 by Leonard McMillan. * * A fairly primitive Ray-Tracing program written * on a Sunday afternoon before Monday's class. * Everything is contained in a single file. The * structure should be fairly easy to extend, with * new primitives, features and other such stuff. * * I tend to write things bottom up (old K&R C * habits die slowly). If you want the big picture * scroll to the applet code at the end and work * your way back here. * ****************************************************/ // The following Applet demonstrates a simple ray tracer with a // mouse-based painting interface for the impatient and Mac owners public class RayTrace extends Applet implements Runnable { final static int CHUNKSIZE = 100; Image screen; Graphics gc; Vector objectList; Vector lightList; Surface currentSurface; Vector3D eye, lookat, up; Vector3D Du, Dv, Vp; float fov; Color background; int width, height; public void init( ) { // initialize the off-screen rendering buffer width = size().width; height = size().height; screen = createImage(width, height); gc = screen.getGraphics(); gc.setColor(getBackground()); gc.fillRect(0, 0, width, height); fov = 30; // default horizonal field of view // Initialize various lists objectList = new Vector(CHUNKSIZE, CHUNKSIZE); lightList = new Vector(CHUNKSIZE, CHUNKSIZE); currentSurface = new Surface(0.8f, 0.2f, 0.9f, 0.2f, 0.4f, 0.4f, 10.0f, 0f, 0f, 1f); // Parse the scene file String filename = getParameter("datafile"); showStatus("Parsing " + filename); InputStream is = null; try { is = new URL(getDocumentBase(), filename).openStream(); ReadInput(is); is.close(); } catch (IOException e) { showStatus("Error reading "+filename); System.err.println("Error reading "+filename); System.exit(-1); } // Initialize more defaults if they weren't specified if (eye == null) eye = new Vector3D(0, 0, 10); if (lookat == null) lookat = new Vector3D(0, 0, 0); if (up == null) up = new Vector3D(0, 1, 0); if (background == null) background = new Color(0,0,0); // Compute viewing matrix that maps a // screen coordinate to a ray direction Vector3D look = new Vector3D(lookat.x - eye.x, lookat.y - eye.y, lookat.z - eye.z); Du = Vector3D.normalize(look.cross(up)); Dv = Vector3D.normalize(look.cross(Du)); float fl = (float)(width / (2*Math.tan((0.5*fov)*Math.PI/180))); Vp = Vector3D.normalize(look); Vp.x = Vp.x*fl - 0.5f*(width*Du.x + height*Dv.x); Vp.y = Vp.y*fl - 0.5f*(width*Du.y + height*Dv.y); Vp.z = Vp.z*fl - 0.5f*(width*Du.z + height*Dv.z); } double getNumber(StreamTokenizer st) throws IOException { if (st.nextToken() != StreamTokenizer.TT_NUMBER) { System.err.println("ERROR: number expected in line "+st.lineno()); throw new IOException(st.toString()); } return st.nval; } void ReadInput(InputStream is) throws IOException { StreamTokenizer st = new StreamTokenizer(is); st.commentChar('#'); scan: while (true) { switch (st.nextToken()) { default: break scan; case StreamTokenizer.TT_WORD: if (st.sval.equals("sphere")) { Vector3D v = new Vector3D((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); float r = (float) getNumber(st); objectList.addElement(new Sphere(currentSurface, v, r)); } else if (st.sval.equals("hemisphere")) { Vector3D v1 = new Vector3D((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); Vector3D v2 = new Vector3D((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); objectList.addElement(new Hemisphere(currentSurface, v1, v2)); } else if (st.sval.equals("eye")) { eye = new Vector3D((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); } else if (st.sval.equals("lookat")) { lookat = new Vector3D((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); } else if (st.sval.equals("up")) { up = new Vector3D((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); } else if (st.sval.equals("fov")) { fov = (float) getNumber(st); } else if (st.sval.equals("background")) { background = new Color((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); } else if (st.sval.equals("light")) { float r = (float) getNumber(st); float g = (float) getNumber(st); float b = (float) getNumber(st); if (st.nextToken() != StreamTokenizer.TT_WORD) { throw new IOException(st.toString()); } if (st.sval.equals("ambient")) { lightList.addElement(new Light(Light.AMBIENT, null, r, g, b)); } else if (st.sval.equals("directional")) { Vector3D v = new Vector3D((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); lightList.addElement(new Light(Light.DIRECTIONAL, v, r, g, b)); } else if (st.sval.equals("point")) { Vector3D v = new Vector3D((float) getNumber(st), (float) getNumber(st), (float) getNumber(st)); lightList.addElement(new Light(Light.POINT, v, r, g, b)); } else { System.err.println("ERROR: in line "+st.lineno()+" at "+st.sval); throw new IOException(st.toString()); } } else if (st.sval.equals("surface")) { float r = (float) getNumber(st); float g = (float) getNumber(st); float b = (float) getNumber(st); float ka = (float) getNumber(st); float kd = (float) getNumber(st); float ks = (float) getNumber(st); float ns = (float) getNumber(st); float kr = (float) getNumber(st); float kt = (float) getNumber(st); float index = (float) getNumber(st); currentSurface = new Surface(r, g, b, ka, kd, ks, ns, kr, kt, index); } break; } } is.close(); if (st.ttype != StreamTokenizer.TT_EOF) throw new IOException(st.toString()); } boolean finished = false; public void paint(Graphics g) { if (finished) g.drawImage(screen, 0, 0, this); } // this overide avoid the unnecessary clear on each paint() public void update(Graphics g) { paint(g); } Thread raytracer; public void start() { if (raytracer == null) { raytracer = new Thread(this); raytracer.start(); } else { raytracer.resume(); } } public void stop() { if (raytracer != null) { raytracer.suspend(); } } private void renderPixel(int i, int j) { Vector3D dir = new Vector3D( i*Du.x + j*Dv.x + Vp.x, i*Du.y + j*Dv.y + Vp.y, i*Du.z + j*Dv.z + Vp.z); Ray ray = new Ray(eye, dir); if (ray.trace(objectList)) { gc.setColor(ray.Shade(lightList, objectList, background)); } else { gc.setColor(background); } gc.drawLine(i, j, i, j); // oh well, it works. } public void run() { Graphics g = getGraphics(); long time = System.currentTimeMillis(); for (int j = 0; j < height; j++) { showStatus("Scanline "+j); for (int i = 0; i < width; i++) { renderPixel(i, j); } g.drawImage(screen, 0, 0, this); // doing this less often speed things up a bit } g.drawImage(screen, 0, 0, this); time = System.currentTimeMillis() - time; showStatus("Rendered in "+(time/60000)+":"+((time%60000)*0.001)); finished = true; } public boolean mouseDown(Event e, int x, int y) { renderPixel(x, y); repaint(); return true; } public boolean mouseDrag(Event e, int x, int y) { renderPixel(x, y); repaint(); return true; } public boolean mouseUp(Event e, int x, int y) { renderPixel(x, y); repaint(); return true; } }