/*
 * Portions Copyright (C) 2003 Sun Microsystems, Inc.
 * All rights reserved.
 */

/*
 *
 * COPYRIGHT NVIDIA CORPORATION 2003. ALL RIGHTS RESERVED.
 * BY ACCESSING OR USING THIS SOFTWARE, YOU AGREE TO:
 *
 *  1) ACKNOWLEDGE NVIDIA'S EXCLUSIVE OWNERSHIP OF ALL RIGHTS
 *     IN AND TO THE SOFTWARE;
 *
 *  2) NOT MAKE OR DISTRIBUTE COPIES OF THE SOFTWARE WITHOUT
 *     INCLUDING THIS NOTICE AND AGREEMENT;
 *
 *  3) ACKNOWLEDGE THAT TO THE MAXIMUM EXTENT PERMITTED BY
 *     APPLICABLE LAW, THIS SOFTWARE IS PROVIDED *AS IS* AND
 *     THAT NVIDIA AND ITS SUPPLIERS DISCLAIM ALL WARRANTIES,
 *     EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED
 *     TO, IMPLIED WARRANTIES OF MERCHANTABILITY  AND FITNESS
 *     FOR A PARTICULAR PURPOSE.
 *
 * IN NO EVENT SHALL NVIDIA OR ITS SUPPLIERS BE LIABLE FOR ANY
 * SPECIAL, INCIDENTAL, INDIRECT, OR CONSEQUENTIAL DAMAGES
 * WHATSOEVER (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS
 * OF BUSINESS PROFITS, BUSINESS INTERRUPTION, LOSS OF BUSINESS
 * INFORMATION, OR ANY OTHER PECUNIARY LOSS), INCLUDING ATTORNEYS'
 * FEES, RELATING TO THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF NVIDIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 */

package demos.vertexProgRefract;

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import java.nio.*;
import java.util.*;
import javax.imageio.*;
import javax.imageio.stream.*;
import javax.swing.*;

import javax.media.opengl.*;
import javax.media.opengl.glu.*;
import com.sun.opengl.utils.*;
import com.sun.opengl.utils.*;
import demos.common.*;
import demos.util.*;
import gleem.*;
import gleem.linalg.*;

/**
  Wavelength-dependent refraction demo<br>
  It's a chromatic aberration!<br>
  sgreen@nvidia.com 4/2001<br><p>

  Currently 3 passes - could do it in 1 with 4 texture units<p>

  Cubemap courtesy of Paul Debevec<p>

  Ported to Java and ARB_fragment_program by Kenneth Russell
*/

public class VertexProgRefract extends Demo {
  public static void main(String[] args) {
    GLCanvas canvas = new GLCanvas();
    VertexProgRefract demo = new VertexProgRefract();
    canvas.addGLEventListener(demo);

    final Animator animator = new Animator(canvas);
    demo.setDemoListener(new DemoListener() {
        public void shutdownDemo() {
          runExit(animator);
        }
        public void repaint() {}
      });

    Frame frame = new Frame("Refraction Using Vertex Programs");
    frame.setLayout(new BorderLayout());
    canvas.setSize(512, 512);
    frame.add(canvas, BorderLayout.CENTER);
    frame.pack();
    frame.show();
    canvas.requestFocus();

    frame.addWindowListener(new WindowAdapter() {
        public void windowClosing(WindowEvent e) {
          runExit(animator);
        }
      });

    animator.start();
  }

  private boolean useRegisterCombiners;
  private boolean initComplete;
  private boolean firstRender = true;
  private int vtxProg;
  private int fragProg;
  private int cubemap;
  private int bunnydl;
  private int obj;

  private GLU  glu  = new GLU();
  private GLUT glut = new GLUT();

  private GLAutoDrawable drawable;
  private ExaminerViewer viewer;
  private boolean doViewAll = true;

  private Time  time = new SystemTime();
  private float animRate = (float) Math.toRadians(-6.0f); // Radians / sec

  private float refract = 1.1f;           // ratio of indicies of refraction
  private float wavelengthDelta = 0.05f;  // difference in refraction for each "wavelength" (R,G,B)
  private float fresnel = 2.0f;           // Fresnel multiplier

  private boolean wire = false;
  private boolean toggleWire = false;

  private static final String transformRefract = 
"!!ARBvp1.0\n" +
"# Refraction\n" +
"\n" +
"# Parameters\n" +
"PARAM mvp [4]       = { state.matrix.mvp };     # modelview projection matrix\n" +
"PARAM mvit[4]       = { state.matrix.modelview.invtrans }; # modelview matrix inverse transpose\n" +
"PARAM mv  [4]       = { state.matrix.modelview }; # modelview matrix\n" +
"PARAM tex [4]       = { state.matrix.texture }; # texture matrix\n" +
"PARAM eyePosition   = program.env[0];           # eye position\n" +
"PARAM fresnel       = program.env[1];           # fresnel multiplier\n" +
"PARAM texScale      = program.env[2];           # texture scale\n" +
"PARAM misc          = program.env[3];           # misc. constants\n" +
"PARAM refraction    = program.env[4];           # refractive index\n" +
"\n" +
"# Per vertex inputs\n" +
"ATTRIB iPos         = vertex.position;          #position\n" +
"ATTRIB iCol0        = vertex.color;             #color\n" +
"ATTRIB iNorm        = vertex.normal;            #normal\n" +
"\n" +
"# Temporaries\n" +
"TEMP r0;\n" +
"TEMP r1;\n" +
"TEMP r2;\n" +
"TEMP r3;\n" +
"TEMP r8;\n" +
"TEMP r9;\n" +
"TEMP r11;\n" +
"\n" +
"# Outputs\n" +
"OUTPUT oPos         = result.position;          #position\n" +
"OUTPUT oCol0        = result.color;             #primary color\n" +
"OUTPUT oTex0        = result.texcoord[0];       #texture coordinate set 0\n" +
"OUTPUT oTex1        = result.texcoord[1];       #texture coordinate set 1\n" +
"\n" +
"\n" +
"# transform vertex position to eye space\n" +
"DP4    r9.x, mv[0], iPos ;\n" +
"DP4    r9.y, mv[1], iPos ;\n" +
"DP4    r9.z, mv[2], iPos ;\n" +
"DP4    r9.w, mv[3], iPos ;\n" +
"\n" +
"# transform normal to eye space\n" +
"DP3    r11.x, mvit[0], iNorm ;\n" +
"DP3    r11.y, mvit[1], iNorm ;\n" +
"DP3    r11.z, mvit[2], iNorm ;\n" +
"\n" +
"# vertex->eye vector\n" +
"ADD    r0, -r9, eyePosition;\n" +
"\n" +
"# normalize\n" +
"DP3    r8.w, r0, r0;\n" +
"RSQ    r8.w, r8.w;\n" +
"MUL    r8, r0, r8.w;       # r8 = eye/incident vector\n" +
"\n" +
"# refraction, Renderman style\n" +
"\n" +
"# float IdotN = I.N;\n" +
"# float k = 1 - eta*eta*(1 - IdotN*IdotN);\n" +
"# return k < 0 ? (0,0,0) : eta*I - (eta*IdotN + sqrt(k))*N;\n" +
"\n" +
"DP3    r0.x, r11, -r8;             # r0 = N.I\n" +
"\n" +
"MAD    r1.x, -r0.x, r0.x, misc.y;  # r1 = -IdotN*IdotN + 1\n" +
"MUL    r1.x, r1.x, refraction.y;   # r1 = -(r1*eta*eta)+1\n" +
"ADD    r1.x, misc.y, -r1.x;\n" +
"\n" +
"RSQ    r2.x, r1.x;\n" +
"RCP    r2.x, r2.x;\n" +
"MAD    r2.x, refraction.x, r0.x, r2.x;\n" +
"MUL    r2, r11, r2.x;\n" +
"MAD    r2, refraction.x, -r8, r2;\n" +
"\n" +
"# transform refracted ray by cubemap transform\n" +
"DP3    oTex0.x, tex[0], r2;\n" +
"DP3    oTex0.y, tex[1], r2;\n" +
"DP3    oTex0.z, tex[2], r2;\n" +
"\n" +
"# calculate reflection\n" +
"MUL    r0, r11, misc.z;\n" +
"DP3    r3.w, r11, r8;\n" +
"MAD    r3, r3.w, r0, -r8;\n" +
"\n" +
"# transform reflected ray by cubemap transform\n" +
"DP3    oTex1.x, tex[0], r3;\n" +
"DP3    oTex1.y, tex[1], r3;\n" +
"DP3    oTex1.z, tex[2], r3;\n" +
"\n" +
"# cheesy Fresnel approximation = (1-(I.N))^p\n" +
"DP3    r0.x, r8, r11;\n" +
"ADD    r0.x, misc.y, -r0.x;\n" +
"MUL    r0.x, r0.x, r0.x;\n" +
"MUL    oCol0, r0.x, fresnel;\n" +
"\n" +
"# transform vertex to clip space\n" +
"DP4    oPos.x, mvp[0], iPos ;\n" +
"DP4    oPos.y, mvp[1], iPos ;\n" +
"DP4    oPos.z, mvp[2], iPos ;\n" +
"DP4    oPos.w, mvp[3], iPos ;\n" +
"\n" +
"END\n";

  public void init(GLAutoDrawable drawable) {
    initComplete = false;
    GL gl = drawable.getGL();
    float cc = 1.0f;
    gl.glClearColor(cc, cc, cc, 1);
    gl.glColor3f(1,1,1);
    gl.glEnable(GL.GL_DEPTH_TEST);

    try {
      initExtension(gl, "GL_ARB_vertex_program");
      initExtension(gl, "GL_VERSION_1_3"); // For multitexturing support
      if (!gl.isExtensionAvailable("GL_ARB_fragment_program")) {
        if (gl.isExtensionAvailable("GL_NV_register_combiners")) {
          useRegisterCombiners = true;
        } else {
          final String message = "This demo requires either the GL_ARB_fragment_program\n" +
            "or GL_NV_register_combiners extension";
          new Thread(new Runnable() {
              public void run() {
                JOptionPane.showMessageDialog(null, message, "Unavailable extension", JOptionPane.ERROR_MESSAGE);
                shutdownDemo();
              }
            }).start();
          throw new RuntimeException(message);
        }
      }
    } catch (RuntimeException e) {
      shutdownDemo();
      throw(e);
    }

    b[' '] = true; // animate by default

    int[] vtxProgTmp = new int[1];
    gl.glGenProgramsARB(1, vtxProgTmp, 0);
    vtxProg = vtxProgTmp[0];
    gl.glBindProgramARB  (GL.GL_VERTEX_PROGRAM_ARB, vtxProg);
    gl.glProgramStringARB(GL.GL_VERTEX_PROGRAM_ARB, GL.GL_PROGRAM_FORMAT_ASCII_ARB, transformRefract.length(), transformRefract);

    gl.glProgramEnvParameter4fARB(GL.GL_VERTEX_PROGRAM_ARB, 0, 0.0f, 0.0f, 0.0f, 1.0f);    // eye position

    gl.glProgramEnvParameter4fARB(GL.GL_VERTEX_PROGRAM_ARB, 1, fresnel, fresnel, fresnel, 1.0f);    // fresnel multiplier

    gl.glProgramEnvParameter4fARB(GL.GL_VERTEX_PROGRAM_ARB, 2, 1.0f, -1.0f, 1.0f, 0.0f);   // texture scale
    gl.glProgramEnvParameter4fARB(GL.GL_VERTEX_PROGRAM_ARB, 3, 0.0f, 1.0f, 2.0f, 3.0f);    // misc constants

    int[] cubemapTmp = new int[1];
    gl.glGenTextures(1, cubemapTmp, 0);
    cubemap = cubemapTmp[0];
    gl.glBindTexture(GL.GL_TEXTURE_CUBE_MAP, cubemap);

    gl.glTexParameteri(GL.GL_TEXTURE_CUBE_MAP, GL.GL_TEXTURE_MAG_FILTER, GL.GL_LINEAR);
    gl.glTexParameteri(GL.GL_TEXTURE_CUBE_MAP, GL.GL_TEXTURE_MIN_FILTER, GL.GL_LINEAR_MIPMAP_LINEAR);

    try {
      loadPNGCubemap(gl, "demos/data/cubemaps/uffizi", true);
    } catch (IOException e) {
      shutdownDemo();
      throw new RuntimeException(e);
    }

    gl.glTexEnvi(GL.GL_TEXTURE_ENV, GL.GL_TEXTURE_ENV_MODE, GL.GL_REPLACE);

    gl.glDisable(GL.GL_CULL_FACE);

    if (useRegisterCombiners) {
      initCombiners(gl);
    } else {
      initFragmentProgram(gl);
    }

    try {
      bunnydl = Bunny.gen3DObjectList(gl);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }

    doViewAll = true;

    // Do this only once per drawable, not once each time the OpenGL
    // context is created
    if (firstRender) {
      firstRender = false;

      drawable.addKeyListener(new KeyAdapter() {
          public void keyTyped(KeyEvent e) {
            dispatchKey(e.getKeyChar());
          }
        });

      // Register the window with the ManipManager
      ManipManager manager = ManipManager.getManipManager();
      manager.registerWindow(drawable);
      this.drawable = drawable;

      viewer = new ExaminerViewer(MouseButtonHelper.numMouseButtons());
      viewer.setNoAltKeyMode(true);
      viewer.setAutoRedrawMode(false);
      viewer.attach(drawable, new BSphereProvider() {
          public BSphere getBoundingSphere() {
            return new BSphere(new Vec3f(0, 0, 0), 1.0f);
          }
        });
      viewer.setVertFOV((float) (15.0f * Math.PI / 32.0f));
      viewer.setZNear(0.1f);
      viewer.setZFar(10.0f);
    }

    initComplete = true;
  }

  public void display(GLAutoDrawable drawable) {
    if (!initComplete) {
      return;
    }

    time.update();

    GL gl = drawable.getGL();
    gl.glClear(GL.GL_COLOR_BUFFER_BIT|GL.GL_DEPTH_BUFFER_BIT);

    if (doViewAll) {
      viewer.viewAll(gl);
      doViewAll = false;
    }

    if (getFlag(' ')) {
      viewer.rotateAboutFocalPoint(new Rotf(Vec3f.Y_AXIS, (float) (time.deltaT() * animRate)));
    }

    if (toggleWire) {
      toggleWire = false;
      wire = !wire;
      if (wire) {
        gl.glPolygonMode(GL.GL_FRONT_AND_BACK, GL.GL_LINE);
      } else {
        gl.glPolygonMode(GL.GL_FRONT_AND_BACK, GL.GL_FILL);
      }
    }

    // draw background
    gl.glDisable(GL.GL_DEPTH_TEST);
    drawSkyBox(gl);
    gl.glEnable(GL.GL_DEPTH_TEST);

    gl.glPushMatrix();

    viewer.update(gl);
    ManipManager.getManipManager().updateCameraParameters(drawable, viewer.getCameraParameters());
    ManipManager.getManipManager().render(drawable, gl);

    gl.glBindProgramARB(GL.GL_VERTEX_PROGRAM_ARB, vtxProg);

    gl.glEnable(GL.GL_VERTEX_PROGRAM_ARB);
    gl.glProgramEnvParameter4fARB(GL.GL_VERTEX_PROGRAM_ARB, 62, fresnel, fresnel, fresnel, 1.0f);

    // set texture transforms
    gl.glActiveTexture(GL.GL_TEXTURE0);
    gl.glBindTexture(GL.GL_TEXTURE_CUBE_MAP, cubemap);
    gl.glEnable(GL.GL_TEXTURE_CUBE_MAP);
    gl.glMatrixMode(GL.GL_TEXTURE);
    gl.glLoadIdentity();
    gl.glScalef(1.0f, -1.0f, 1.0f);
    viewer.updateInverseRotation(gl);

    gl.glActiveTexture(GL.GL_TEXTURE1);
    gl.glBindTexture(GL.GL_TEXTURE_CUBE_MAP, cubemap);
    gl.glEnable(GL.GL_TEXTURE_CUBE_MAP);
    gl.glMatrixMode(GL.GL_TEXTURE);
    gl.glLoadIdentity();
    gl.glScalef(1.0f, -1.0f, 1.0f);
    viewer.updateInverseRotation(gl);

    if (useRegisterCombiners) {
      gl.glEnable(GL.GL_REGISTER_COMBINERS_NV);
    } else {
      gl.glBindProgramARB(GL.GL_FRAGMENT_PROGRAM_ARB, fragProg);
      gl.glEnable(GL.GL_FRAGMENT_PROGRAM_ARB);
    }

    gl.glColor3f(1.0f, 1.0f, 1.0f);

    if (getFlag('s')) {
      // single pass
      setRefraction(gl, refract);
      drawObj(gl, obj);

    } else {
      // red pass
      gl.glColorMask(true, false, false, false);
      setRefraction(gl, refract);
      drawObj(gl, obj);
  
      gl.glDepthMask(false);
      gl.glDepthFunc(GL.GL_EQUAL);

      // green pass
      gl.glColorMask(false, true, false, false);
      setRefraction(gl, refract + wavelengthDelta);
      drawObj(gl, obj);

      // blue pass
      gl.glColorMask(false, false, true, false);
      setRefraction(gl, refract + (wavelengthDelta * 2));
      drawObj(gl, obj);

      gl.glDepthMask(true);
      gl.glDepthFunc(GL.GL_LESS);
      gl.glColorMask(true, true, true, false);
    }

    if (useRegisterCombiners) {
      gl.glDisable(GL.GL_REGISTER_COMBINERS_NV);
    } else {
      gl.glDisable(GL.GL_FRAGMENT_PROGRAM_ARB);
    }
    gl.glDisable(GL.GL_VERTEX_PROGRAM_ARB);

    gl.glMatrixMode(GL.GL_MODELVIEW);
    gl.glPopMatrix();
  }

  // Unused routines
  public void reshape(GLAutoDrawable drawable, int x, int y, int width, int height) {}
  public void displayChanged(GLAutoDrawable drawable, boolean modeChanged, boolean deviceChanged) {}

  //----------------------------------------------------------------------
  // Internals only below this point
  //
  public void shutdownDemo() {
    ManipManager.getManipManager().unregisterWindow(drawable);
    drawable.removeGLEventListener(this);
    super.shutdownDemo();
  }

  private boolean[] b = new boolean[256];
  private void dispatchKey(char k) {
    setFlag(k, !getFlag(k));

    // Quit on escape or 'q'
    if ((k == (char) 27) || (k == 'q')) {
      shutdownDemo();
      return;
    }

    switch (k) {
    case '1':
      obj = 0;
      break;

    case '2':
      obj = 1;
      break;

    case '3':
      obj = 2;
      break;

    case '4':
      obj = 3;
      break;

    case 'v':
      doViewAll = true;
      break;

    case 'w':
      toggleWire = true;
      break;

    default:
      break;
    }
  }

  private void setFlag(char key, boolean val) {
    b[((int) key) & 0xFF] = val;
  }

  private boolean getFlag(char key) {
    return b[((int) key) & 0xFF];
  }

  // FIXME: note we found that we had to swap the negy and posy portions of the cubemap.
  // Not sure why this is the case. Vertical flip in the image read? Possible, but doesn't
  // appear to be the case (have tried this and produced wrong results at the time).
  String[] suffixes = { "posx", "negx", "negy", "posy", "posz", "negz" };
  int[] targets = { GL.GL_TEXTURE_CUBE_MAP_POSITIVE_X,
                    GL.GL_TEXTURE_CUBE_MAP_NEGATIVE_X,
                    GL.GL_TEXTURE_CUBE_MAP_POSITIVE_Y,
                    GL.GL_TEXTURE_CUBE_MAP_NEGATIVE_Y,
                    GL.GL_TEXTURE_CUBE_MAP_POSITIVE_Z,
                    GL.GL_TEXTURE_CUBE_MAP_NEGATIVE_Z };
  private void loadPNGCubemap(GL gl, String baseName, boolean mipmapped) throws IOException {
    for (int i = 0; i < suffixes.length; i++) {
      String resourceName = baseName + "_" + suffixes[i] + ".png";
      // Note: use of BufferedInputStream works around 4764639/4892246
      BufferedImage img = ImageIO.read(new BufferedInputStream(getClass().getClassLoader().getResourceAsStream(resourceName)));
      if (img == null) {
        throw new RuntimeException("Error reading PNG image " + resourceName);
      }
      makeRGBTexture(gl, img, targets[i], mipmapped);
    }
  }

  private void makeRGBTexture(GL gl, BufferedImage img, int target, boolean mipmapped) {
    switch (img.getType()) {
    case BufferedImage.TYPE_3BYTE_BGR:
    case BufferedImage.TYPE_CUSTOM: {
      byte[] data = ((DataBufferByte) img.getRaster().getDataBuffer()).getData();
      if (mipmapped) {
        glu.gluBuild2DMipmaps(target, GL.GL_RGB8, img.getWidth(), img.getHeight(), GL.GL_RGB,
                              GL.GL_UNSIGNED_BYTE, ByteBuffer.wrap(data));
      } else {
        gl.glTexImage2D(target, 0, GL.GL_RGB, img.getWidth(), img.getHeight(), 0,
                        GL.GL_RGB, GL.GL_UNSIGNED_BYTE, ByteBuffer.wrap(data));
      }
      break;
    }

    case BufferedImage.TYPE_INT_RGB: {
      int[] data = ((DataBufferInt) img.getRaster().getDataBuffer()).getData();
      if (mipmapped) {
        glu.gluBuild2DMipmaps(target, GL.GL_RGB8, img.getWidth(), img.getHeight(), GL.GL_RGB,
                              GL.GL_UNSIGNED_BYTE, IntBuffer.wrap(data));
      } else {
        gl.glTexImage2D(target, 0, GL.GL_RGB, img.getWidth(), img.getHeight(), 0,
                        GL.GL_RGB, GL.GL_UNSIGNED_BYTE, IntBuffer.wrap(data));
      }
      break;
    }

    default:
      throw new RuntimeException("Unsupported image type " + img.getType());
    }
  }

  private void initExtension(GL gl, String glExtensionName) {
    if (!gl.isExtensionAvailable(glExtensionName)) {
      final String message = "OpenGL extension \"" + glExtensionName + "\" not available";
      new Thread(new Runnable() {
          public void run() {
            JOptionPane.showMessageDialog(null, message, "Unavailable extension", JOptionPane.ERROR_MESSAGE);
            shutdownDemo();
          }
        }).start();
      throw new RuntimeException(message);
    }
  }

  // initalize texture combiners to compute:
  // refraction*(1-fresnel) + reflection*fresnel
  private void initCombiners(GL gl) {
    gl.glCombinerParameteriNV(GL.GL_NUM_GENERAL_COMBINERS_NV, 1);
      
    // combiner 0
    // a*b+c*d
    gl.glCombinerInputNV(GL.GL_COMBINER0_NV, GL.GL_RGB, GL.GL_VARIABLE_A_NV, GL.GL_TEXTURE0, GL.GL_UNSIGNED_IDENTITY_NV, GL.GL_RGB);
    gl.glCombinerInputNV(GL.GL_COMBINER0_NV, GL.GL_RGB, GL.GL_VARIABLE_B_NV, GL.GL_PRIMARY_COLOR_NV, GL.GL_UNSIGNED_INVERT_NV, GL.GL_RGB);
    gl.glCombinerInputNV(GL.GL_COMBINER0_NV, GL.GL_RGB, GL.GL_VARIABLE_C_NV, GL.GL_TEXTURE1, GL.GL_UNSIGNED_IDENTITY_NV, GL.GL_RGB);
    gl.glCombinerInputNV(GL.GL_COMBINER0_NV, GL.GL_RGB, GL.GL_VARIABLE_D_NV, GL.GL_PRIMARY_COLOR_NV, GL.GL_UNSIGNED_IDENTITY_NV, GL.GL_RGB);

    // output:
    // (stage, portion, abOutput, cdOutput, sumOutput, scale, bias, abDotProduct, cdDotProduct, muxSum)
    gl.glCombinerOutputNV(GL.GL_COMBINER0_NV, GL.GL_RGB, GL.GL_DISCARD_NV, GL.GL_DISCARD_NV, GL.GL_SPARE0_NV, GL.GL_NONE, GL.GL_NONE, false, false, false);
      
    // final combiner
    // output: Frgb = A*B + (1-A)*C + D
    // (variable, input, mapping, componentUsage);
    gl.glFinalCombinerInputNV(GL.GL_VARIABLE_A_NV, GL.GL_SPARE0_NV, GL.GL_UNSIGNED_IDENTITY_NV, GL.GL_RGB);
    gl.glFinalCombinerInputNV(GL.GL_VARIABLE_B_NV, GL.GL_ZERO, GL.GL_UNSIGNED_INVERT_NV, GL.GL_RGB);
    gl.glFinalCombinerInputNV(GL.GL_VARIABLE_C_NV, GL.GL_ZERO, GL.GL_UNSIGNED_IDENTITY_NV, GL.GL_RGB);
    gl.glFinalCombinerInputNV(GL.GL_VARIABLE_D_NV, GL.GL_ZERO, GL.GL_UNSIGNED_IDENTITY_NV, GL.GL_RGB);
  }

  private void initFragmentProgram(GL gl) {
    int[] fragProgTmp = new int[1];
    gl.glGenProgramsARB(1, fragProgTmp, 0);
    fragProg = fragProgTmp[0];
    String combineFragProg =
"!!ARBfp1.0\n" +
"# compute refraction*(1-fresnel) + reflection*fresnel\n" +
"TEMP texSamp0, texSamp1;\n" +
"TEMP invFresnel;\n" +
"PARAM one = { 1.0, 1.0, 1.0, 1.0 };\n" +
"TEX texSamp0, fragment.texcoord[0], texture[0], CUBE;\n" +
"TEX texSamp1, fragment.texcoord[1], texture[1], CUBE;\n" +
"SUB invFresnel, one, fragment.color;\n" +
"MUL texSamp0, texSamp0, invFresnel;\n" +
"MUL texSamp1, texSamp1, fragment.color;\n" +
"ADD texSamp0, texSamp0, texSamp1;\n" +
"MOV result.color, texSamp0;\n" +
"END";

    gl.glBindProgramARB  (GL.GL_FRAGMENT_PROGRAM_ARB, fragProg);
    gl.glProgramStringARB(GL.GL_FRAGMENT_PROGRAM_ARB, GL.GL_PROGRAM_FORMAT_ASCII_ARB,
                          combineFragProg.length(), combineFragProg);
    int[] errPos = new int[1];
    gl.glGetIntegerv(GL.GL_PROGRAM_ERROR_POSITION_ARB, errPos, 0);
    if (errPos[0] >= 0) {
      System.out.println("Fragment program failed to load:");
      String errMsg = gl.glGetString(GL.GL_PROGRAM_ERROR_STRING_ARB);
      if (errMsg == null) {
        System.out.println("[No error message available]");
      } else {
        System.out.println("Error message: \"" + errMsg + "\"");
      }
      System.out.println("Error occurred at position " + errPos[0] + " in program:");
      int endPos = errPos[0];
      while (endPos < combineFragProg.length() && combineFragProg.charAt(endPos) != '\n') {
        ++endPos;
      }
      System.out.println(combineFragProg.substring(errPos[0], endPos));
    }
  }

  private void drawSkyBox(GL gl) {
    // Compensates for ExaminerViewer's modification of modelview matrix
    gl.glMatrixMode(GL.GL_MODELVIEW);
    gl.glLoadIdentity();

    gl.glActiveTexture(GL.GL_TEXTURE1);
    gl.glDisable(GL.GL_TEXTURE_CUBE_MAP);
  
    gl.glActiveTexture(GL.GL_TEXTURE0);
    gl.glBindTexture(GL.GL_TEXTURE_CUBE_MAP, cubemap);
    gl.glEnable(GL.GL_TEXTURE_CUBE_MAP);

    // This is a workaround for a driver bug on Mac OS X where the
    // normals are not being sent down to the hardware in
    // GL_NORMAL_MAP texgen mode. Temporarily enabling lighting
    // causes the normals to be sent down. Thanks to Ken Dyke.
    gl.glEnable(GL.GL_LIGHTING);

    gl.glTexGeni(GL.GL_S, GL.GL_TEXTURE_GEN_MODE, GL.GL_NORMAL_MAP);
    gl.glTexGeni(GL.GL_T, GL.GL_TEXTURE_GEN_MODE, GL.GL_NORMAL_MAP);
    gl.glTexGeni(GL.GL_R, GL.GL_TEXTURE_GEN_MODE, GL.GL_NORMAL_MAP);

    gl.glEnable(GL.GL_TEXTURE_GEN_S);
    gl.glEnable(GL.GL_TEXTURE_GEN_T);
    gl.glEnable(GL.GL_TEXTURE_GEN_R);

    gl.glTexEnvi(GL.GL_TEXTURE_ENV, GL.GL_TEXTURE_ENV_MODE, GL.GL_REPLACE);

    gl.glMatrixMode(GL.GL_TEXTURE);
    gl.glPushMatrix();
    gl.glLoadIdentity();
    gl.glScalef(1.0f, -1.0f, 1.0f);
    viewer.updateInverseRotation(gl);
    
    glut.glutSolidSphere(5.0, 40, 20);

    gl.glDisable(GL.GL_LIGHTING);

    gl.glPopMatrix();
    gl.glMatrixMode(GL.GL_MODELVIEW);

    gl.glDisable(GL.GL_TEXTURE_GEN_S);
    gl.glDisable(GL.GL_TEXTURE_GEN_T);
    gl.glDisable(GL.GL_TEXTURE_GEN_R);
  }

  private void drawObj(GL gl, int obj) {
    switch(obj) {
    case 0:
      gl.glCallList(bunnydl);
      break;
    
    case 1:
      glut.glutSolidSphere(0.5, 64, 64);
      break;

    case 2:
      glut.glutSolidTorus(0.25, 0.5, 64, 64);
      break;

    case 3:
      drawPlane(gl, 1.0f, 1.0f, 50, 50);
      break;
    }
  }

  private void setRefraction(GL gl, float index) {
    gl.glProgramEnvParameter4fARB(GL.GL_VERTEX_PROGRAM_ARB, 4, index, index*index, 0.0f, 0.0f);
  }

  // draw square subdivided into quad strips
  private void drawPlane(GL gl, float w, float h, int rows, int cols) {
    int x, y;
    float vx, vy, s, t;
    float ts, tt, tw, th;

    ts = 1.0f / cols;
    tt = 1.0f / rows;

    tw = w / cols;
    th = h / rows;

    gl.glNormal3f(0.0f, 0.0f, 1.0f);

    for(y=0; y<rows; y++) {
      gl.glBegin(GL.GL_QUAD_STRIP);
      for(x=0; x<=cols; x++) {
        vx = tw * x -(w/2.0f);
        vy = th * y -(h/2.0f);
        s = ts * x;
        t = tt * y;

        gl.glTexCoord2f(s, t);
        gl.glColor3f(s, t, 0.0f);
        gl.glVertex3f(vx, vy, 0.0f);

        gl.glColor3f(s, t + tt, 0.0f);
        gl.glTexCoord2f(s, t + tt);
        gl.glVertex3f(vx, vy + th, 0.0f);
      }
      gl.glEnd();
    }
  }

  private static void runExit(final Animator animator) {
    // Note: calling System.exit() synchronously inside the draw,
    // reshape or init callbacks can lead to deadlocks on certain
    // platforms (in particular, X11) because the JAWT's locking
    // routines cause a global AWT lock to be grabbed. Instead run
    // the exit routine in another thread.
    new Thread(new Runnable() {
        public void run() {
          animator.stop();
          System.exit(0);
        }
      }).start();
  }
}