Added NVidia VertexArrayRange demo

1 files changed, 709 insertions, 0 deletions

diff --git a/demos/NVidia/VertexArrayRange.java b/demos/NVidia/VertexArrayRange.java
new file mode 100644
index 0000000..52c6591
--- /dev/null
+++ b/demos/NVidia/VertexArrayRange.java
@@ -0,0 +1,709 @@
+import java.awt.*;
+import java.awt.event.*;
+import java.nio.*;
+import java.util.*;
+import gl4java.*;
+import gl4java.awt.*;
+import gl4java.drawable.*;
+
+/** <P> A port of NVidia's Vertex Array Range demonstration to OpenGL
+    for Java and the Java programming language. The current web site
+    for the demo (which does not appear to contain the original C++
+    source code for this demo) is <a href =
+    "http://developer.nvidia.com/view.asp?IO=Using_GL_NV_fence">here</a>. </P>
+
+    <P> This demonstration requires the following:
+
+    <ul>
+    <li> A JDK 1.4 implementation
+    <li> an NVidia-based card
+    <li> a recent set of drivers
+    </ul>
+
+    </P>
+*/
+
+public class VertexArrayRange {
+  private boolean[] b = new boolean[256];
+  private GLFunc14 gl;
+  private GLUFunc14 glu;
+  private static final int SIZEOF_FLOAT = 4;
+  private static final int STRIP_SIZE  = 48;
+  private int tileSize   = 9 * STRIP_SIZE;
+  private int numBuffers = 4;
+  private int bufferLength = 1000000;
+  private int bufferSize   = bufferLength * SIZEOF_FLOAT;
+  private static final int SIN_ARRAY_SIZE = 1024;
+  
+
+  private FloatBuffer bigArrayVar;
+  private int[][]    elements;
+  private float[]    xyArray;
+
+  // NOTE: we could as well use direct buffers for the "slow" vertices
+  // and normals. However, we do not use FloatBuffers to wrap these
+  // float[] arrays to prevent breaking the Class Hierarchy Analysis
+  // which (currently) allows inlining of all accessors in the
+  // innermost loop. Avoiding mixing direct and non-direct java.nio
+  // buffers in the same application is currently recommended
+  // practice.
+  static class VarBuffer {
+    public FloatBuffer fastVertices;
+    public FloatBuffer fastNormals;
+    public int        fence;
+    public float[]    slowVertices;
+    public float[]    slowNormals;
+  }
+  private VarBuffer[] buffers;
+  
+  private float[] sinArray;
+  private float[] cosArray;
+
+  // Primitive: GL_QUAD_STRIP, GL_LINE_STRIP, or GL_POINTS
+  private int primitive = GLEnum.GL_QUAD_STRIP;
+
+  // Animation parameters
+  private float hicoef = .06f;
+  private float locoef = .10f;
+  private float hifreq = 6.1f;
+  private float lofreq = 2.5f;
+  private float phaseRate = .02f;
+  private float phase2Rate = -0.12f;
+  private float phase  = 0;
+  private float phase2 = 0;
+
+  // Temporaries for computation
+  float[] ysinlo = new float[STRIP_SIZE];
+  float[] ycoslo = new float[STRIP_SIZE];
+  float[] ysinhi = new float[STRIP_SIZE];
+  float[] ycoshi = new float[STRIP_SIZE];
+
+  // For thread-safety when dealing with keypresses
+  private volatile boolean mustChangeState = false;
+
+  // Frames-per-second computation
+  private boolean firstProfiledFrame;
+  private int     profiledFrameCount;
+  private int     numDrawElementsCalls;
+  private long startTimeMillis;
+
+  static class PeriodicIterator {
+    public PeriodicIterator(int arraySize,
+                            float period,
+                            float initialOffset,
+                            float delta) {
+      float arrayDelta =  arraySize * (delta / period); // floating-point steps-per-increment
+      increment = (int)(arrayDelta * (1<<16));          // fixed-point steps-per-increment
+
+      float offset = arraySize * (initialOffset / period); // floating-point initial index
+      initOffset = (int)(offset * (1<<16));                // fixed-point initial index
+        
+        arraySizeMask = 0;
+        int i = 20; // array should be reasonably sized...
+        while((arraySize & (1<<i)) == 0) {
+          i--;
+        }
+        arraySizeMask = (1<<i)-1;        
+        index = initOffset;
+    }
+
+    public PeriodicIterator(PeriodicIterator arg) {
+      this.arraySizeMask = arg.arraySizeMask;
+      this.increment = arg.increment;
+      this.initOffset = arg.initOffset;
+      this.index = arg.index;
+    }
+
+    public int getIndex() {
+      return (index >> 16) & arraySizeMask;
+    }
+
+    public void incr() {
+      index += increment;
+    }
+
+    public void decr() {
+      index -= increment;
+    }
+
+    public void reset() {
+      index = initOffset;
+    }
+
+    //----------------------------------------------------------------------
+    // Internals only below this point
+    //
+
+    private int arraySizeMask;
+    // fraction bits == 16
+    private int increment;
+    private int initOffset;
+    private int index;
+  }
+
+  public static void usage(String className) {
+    System.out.println("usage: java " + className + " [-slow]");
+    System.out.println("-slow flag starts up using data in the Java heap");
+    System.exit(0);
+  }
+
+  public static void main(String[] args) {
+    new VertexArrayRange().run(args);
+  }
+
+  public void run(String[] args) {
+    boolean startSlow = false;
+
+    if (args.length > 1) {
+      usage(getClass().getName());
+    }
+
+    if (args.length == 1) {
+      if (args[0].equals("-slow")) {
+        startSlow = true;
+      } else {
+        usage(getClass().getName());
+      }
+    }
+
+    if (!startSlow) {
+      setFlag('v', true);   // VAR on
+    }
+    setFlag(' ', true);   // animation on
+    setFlag('i', true);   // infinite viewer and light
+
+    // FIXME: add glGetString
+    Frame frame = new Frame("Very Simple NV_vertex_array_range demo");
+    frame.setLayout(new BorderLayout());
+    GLCapabilities caps = new GLCapabilities(true, false, true, 0, 0, 0, 0, 0);
+
+    GLAnimCanvas canvas = GLDrawableFactory.getFactory().createGLAnimCanvas(caps, 800, 800);
+    VARListener listener = new VARListener();
+    canvas.addGLEventListener(listener);
+    canvas.setUseRepaint(false);
+    canvas.setUseFpsSleep(false);
+    canvas.setUseYield(false);
+    frame.add(canvas, BorderLayout.CENTER);
+    frame.pack();
+    frame.show();
+
+    canvas.requestFocus();
+    canvas.start();
+  }
+
+  //----------------------------------------------------------------------
+  // Internals only below this point
+  //
+
+  private void setFlag(char key, boolean val) {
+    b[((int) key) & 0xFF] = val;
+  }
+
+  private boolean getFlag(char key) {
+    return b[((int) key) & 0xFF];
+  }
+  
+  private static boolean testPresent(String function) {
+    return GLContext.gljTestGLProc(function, false);
+  }
+
+  private static void ensurePresent(String function) {
+    if (!testPresent(function)) {
+      throw new RuntimeException("OpenGL routine \"" + function + "\" not present");
+    }
+  }
+
+  class VARListener implements GLEventListener, GLEnum {
+    public void init(GLDrawable drawable) {
+      gl = (GLFunc14) drawable.getGL();
+      glu = (GLUFunc14) drawable.getGLU();
+
+      gl.glEnable(GL_DEPTH_TEST);
+
+      ensurePresent("glVertexArrayRangeNV");
+      ensurePresent("glGenFencesNV");
+      ensurePresent("glSetFenceNV");
+      ensurePresent("glTestFenceNV");
+      ensurePresent("glFinishFenceNV");
+      ensurePresent("glAllocateMemoryNV");
+      
+      gl.glClearColor(0, 0, 0, 0);
+
+      gl.glEnable(GL_LIGHT0);
+      gl.glEnable(GL_LIGHTING);
+      gl.glEnable(GL_NORMALIZE);
+      gl.glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, new float[]  {.1f, .1f,    0, 1});
+      gl.glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, new float[]  {.6f, .6f,  .1f, 1});
+      gl.glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, new float[] { 1,    1, .75f, 1});
+      gl.glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 128.f);
+
+      gl.glLightfv(GL_LIGHT0, GL_POSITION, new float[] { .5f, 0, .5f, 0});
+      gl.glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, 0);
+
+      // NOTE: it looks like GLUT (or something else) sets up the
+      // projection matrix in the C version of this demo.
+      gl.glMatrixMode(GL_PROJECTION);
+      gl.glLoadIdentity();
+      glu.gluPerspective(60, 1.0, 0.1, 100);
+      gl.glMatrixMode(GL_MODELVIEW);
+
+      allocateBigArray(true);
+      allocateBuffers();
+
+      sinArray = new float[SIN_ARRAY_SIZE];
+      cosArray = new float[SIN_ARRAY_SIZE];
+    
+      for (int i = 0; i < SIN_ARRAY_SIZE; i++) {
+        double step = i * 2 * Math.PI / SIN_ARRAY_SIZE;
+        sinArray[i] = (float) Math.sin(step);
+        cosArray[i] = (float) Math.cos(step);
+      }
+
+      if (getFlag('v')) {
+        gl.glEnableClientState(GL_VERTEX_ARRAY_RANGE_NV);
+        gl.glVertexArrayRangeNV(bufferSize, bigArrayVar);
+      }
+      gl.glEnableClientState(GL_VERTEX_ARRAY);
+      gl.glEnableClientState(GL_NORMAL_ARRAY);
+
+      computeElements();
+
+      drawable.addKeyListener(new KeyAdapter() {
+          public void keyTyped(KeyEvent e) {
+            dispatchKey(e.getKeyChar());
+          }
+        });
+    }
+
+    private void allocateBuffers() {
+      buffers = new VarBuffer[numBuffers];
+
+      int sliceSize = bufferLength / numBuffers;
+      int[] fences = new int[1];
+      for (int i = 0; i < numBuffers; i++) {
+        buffers[i] = new VarBuffer();
+        int startIndex = i * sliceSize;
+	buffers[i].fastVertices = sliceBuffer(bigArrayVar, startIndex, sliceSize);
+	buffers[i].fastNormals  = sliceBuffer(buffers[i].fastVertices, 3,
+					      buffers[i].fastVertices.limit() - 3);
+        buffers[i].slowVertices = new float[sliceSize];
+        buffers[i].slowNormals  = new float[sliceSize];
+	gl.glGenFencesNV(1, fences);
+	buffers[i].fence = fences[0];
+      }
+    }
+
+    private void dispatchKey(char k) {
+      setFlag(k, !getFlag(k));
+      // Quit on escape or 'q'
+      if ((k == (char) 27) || (k == 'q')) {
+        System.exit(0);
+      }
+    
+      if (k == 'r') {
+        if (getFlag(k)) {
+          profiledFrameCount = 0;
+          numDrawElementsCalls = 0;
+          firstProfiledFrame = true;
+        }
+      }
+
+      if (k == 'w') {
+        if (getFlag(k)) {
+          primitive = GL_LINE_STRIP;
+        } else {
+          primitive = GL_QUAD_STRIP;
+        }
+      }
+
+      if (k == 'p') {
+        if (getFlag(k)) {
+          primitive = GL_POINTS;
+        } else {
+          primitive = GL_QUAD_STRIP;
+        }
+      }
+
+      if (k == 'v') {
+        mustChangeState = true;
+      }
+    
+      if (k == 'd') {
+        if (getFlag(k)) {
+          gl.glDisable(GL_LIGHTING);
+        } else {
+          gl.glEnable(GL_LIGHTING);
+        }
+      }
+      
+      if (k == 'i') {
+        if(getFlag(k)) {
+          // infinite light
+          gl.glLightfv(GL_LIGHT0, GL_POSITION, new float[] { .5f, 0, .5f, 0 });
+          gl.glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, 0);
+        } else {
+          gl.glLightfv(GL_LIGHT0, GL_POSITION, new float[] { .5f, 0, -.5f,1 });
+          gl.glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, 1);
+        }
+      }
+
+      if('h'==k)
+        hicoef += .005;
+      if('H'==k)
+        hicoef -= .005;
+      if('l'==k)
+        locoef += .005;
+      if('L'==k)
+        locoef -= .005;
+      if('1'==k)
+        lofreq += .1f;
+      if('2'==k)
+        lofreq -= .1f;
+      if('3'==k)
+        hifreq += .1f;
+      if('4'==k)
+        hifreq -= .1f;
+      if('5'==k)
+        phaseRate += .01f;
+      if('6'==k)
+        phaseRate -= .01f;
+      if('7'==k)
+        phase2Rate += .01f;
+      if('8'==k)
+        phase2Rate -= .01f;
+
+      if('t'==k) {
+        if(tileSize < 864) {
+          tileSize += STRIP_SIZE;
+          computeElements();
+          System.err.println("tileSize = " + tileSize);
+        }
+      }
+
+      if('T'==k) {
+        if(tileSize > STRIP_SIZE) { 
+          tileSize -= STRIP_SIZE;
+          computeElements();
+          System.err.println("tileSize = " + tileSize);
+        }
+      }
+    }
+
+    public void display(GLDrawable drawable) {
+      // Check to see whether to animate
+      if (getFlag(' ')) {
+        phase += phaseRate;
+        phase2 += phase2Rate;
+      
+        if (phase > (float) (20 * Math.PI)) {
+          phase = 0;
+        }
+
+        if (phase2 < (float) (-20 * Math.PI)) {
+          phase2 = 0;
+        }
+      }
+
+      PeriodicIterator loX =
+        new PeriodicIterator(SIN_ARRAY_SIZE, (float) (2 * Math.PI), phase, (float) ((1.f/tileSize)*lofreq*Math.PI));
+      PeriodicIterator loY = new PeriodicIterator(loX);
+      PeriodicIterator hiX =
+        new PeriodicIterator(SIN_ARRAY_SIZE, (float) (2 * Math.PI), phase2, (float) ((1.f/tileSize)*hifreq*Math.PI));
+      PeriodicIterator hiY = new PeriodicIterator(hiX);
+    
+      if (mustChangeState) {
+        if (getFlag('v')) {
+          gl.glEnableClientState(GL_VERTEX_ARRAY_RANGE_NV);
+          gl.glVertexArrayRangeNV(bufferSize, bigArrayVar);
+        } else {
+          gl.glDisableClientState(GL_VERTEX_ARRAY_RANGE_NV);
+        }
+        mustChangeState = false;
+      }
+
+      gl.glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    
+      gl.glPushMatrix();
+
+      gl.glLoadMatrixf(new float[] {
+        1, 0, 0, 0,
+        0, 1, 0, 0,
+        0, 0, 1, 0,
+        0, 0, -1, 1
+      });
+
+      // FIXME: add mouse interaction
+      // camera.apply_inverse_transform();
+      // object.apply_transform();
+
+      int cur = 0;
+      int numSlabs = tileSize / STRIP_SIZE;
+
+      // Fast case/slow case split. The reason for this is to avoid
+      // any potential problems with the compilers not being able to
+      // inline the native array accesses if more than one subclass of
+      // FloatArray is loaded.
+
+      if (getFlag('v')) {
+        // Fast case
+        for(int slab = 0; slab < numSlabs; slab++) {
+          cur = slab % numBuffers;
+          if (slab >= numBuffers) {
+            if (!gl.glTestFenceNV(buffers[cur].fence)) {
+              gl.glFinishFenceNV(buffers[cur].fence);
+            }
+          }
+
+          FloatBuffer v = buffers[cur].fastVertices;
+          int vertexIndex = 0;
+
+          gl.glVertexPointer(3, GL_FLOAT, 6 * SIZEOF_FLOAT, v);
+          gl.glNormalPointer(GL_FLOAT, 6 * SIZEOF_FLOAT, buffers[cur].fastNormals);
+
+          for(int jj=0; jj < STRIP_SIZE; jj++) {
+            ysinlo[jj] = sinArray[loY.getIndex()];
+            ycoslo[jj] = cosArray[loY.getIndex()]; loY.incr();
+            ysinhi[jj] = sinArray[hiY.getIndex()];
+            ycoshi[jj] = cosArray[hiY.getIndex()]; hiY.incr();
+          }
+          loY.decr();
+          hiY.decr();
+        
+          for(int i = 0; i < tileSize; i++) {
+            float x = xyArray[i];
+            int loXIndex = loX.getIndex();
+            int hiXIndex = hiX.getIndex();
+
+            int jOffset = (STRIP_SIZE-1)*slab;
+            float nx = locoef * -cosArray[loXIndex] + hicoef * -cosArray[hiXIndex];
+
+            // Help the HotSpot Client Compiler by hoisting loop
+            // invariant variables into locals. Note that this may be
+            // good practice for innermost loops anyway since under
+            // the new memory model operations like accidental
+            // synchronization may force any compiler to reload these
+            // fields from memory, destroying their ability to
+            // optimize.
+            float locoef_tmp = locoef;
+            float hicoef_tmp = hicoef;
+            float[] ysinlo_tmp = ysinlo;
+            float[] ysinhi_tmp = ysinhi;
+            float[] ycoslo_tmp = ycoslo;
+            float[] ycoshi_tmp = ycoshi;
+            float[] sinArray_tmp = sinArray;
+            float[] xyArray_tmp = xyArray;
+
+            for(int j = 0; j < STRIP_SIZE; j++) {
+              float y;
+              
+              y = xyArray_tmp[j + jOffset];
+
+              float ny;
+
+              v.put(vertexIndex, x);
+              v.put(vertexIndex + 1, y);
+              v.put(vertexIndex + 2, (locoef_tmp * (sinArray_tmp[loXIndex] + ysinlo_tmp[j]) + 
+                                      hicoef_tmp * (sinArray_tmp[hiXIndex] + ysinhi_tmp[j])));
+              v.put(vertexIndex + 3, nx);
+              ny = locoef_tmp * -ycoslo_tmp[j] + hicoef_tmp * -ycoshi_tmp[j];
+              v.put(vertexIndex + 4, ny);
+              v.put(vertexIndex + 5, .15f); //.15f * (1.f - sqrt(nx * nx + ny * ny));
+              vertexIndex += 6;
+            }
+            loX.incr();
+            hiX.incr();
+          }
+          loX.reset();
+          hiX.reset();
+
+          for (int i = 0; i < elements.length; i++) {
+            ++numDrawElementsCalls;
+            gl.glDrawElements(primitive, elements[i].length, GL_UNSIGNED_INT, elements[i]);
+            if(getFlag('f')) {
+              gl.glFlush();
+            }
+          }
+        
+          gl.glSetFenceNV(buffers[cur].fence, GL_ALL_COMPLETED_NV);
+        }
+      } else {
+        // Slow case
+        for(int slab = 0; slab < numSlabs; slab++) {
+          cur = slab % numBuffers;
+          if (slab >= numBuffers) {
+	    if (!gl.glTestFenceNV(buffers[cur].fence)) {
+	      gl.glFinishFenceNV(buffers[cur].fence);
+	    }
+          }
+
+          float[] v = buffers[cur].slowVertices;
+          float[] n = buffers[cur].slowNormals;
+          int vertexIndex = 0;
+
+          for(int jj=0; jj < STRIP_SIZE; jj++) {
+            ysinlo[jj] = sinArray[loY.getIndex()];
+            ycoslo[jj] = cosArray[loY.getIndex()]; loY.incr();
+            ysinhi[jj] = sinArray[hiY.getIndex()];
+            ycoshi[jj] = cosArray[hiY.getIndex()]; hiY.incr();
+          }
+          loY.decr();
+          hiY.decr();
+        
+          for(int i = 0; i < tileSize; i++) {
+            float x = xyArray[i];
+            int loXIndex = loX.getIndex();
+            int hiXIndex = hiX.getIndex();
+
+            int jOffset = (STRIP_SIZE-1)*slab;
+            float nx = locoef * -cosArray[loXIndex] + hicoef * -cosArray[hiXIndex];
+
+            // Help the HotSpot Client Compiler by hoisting loop
+            // invariant variables into locals. Note that this may be
+            // good practice for innermost loops anyway since under
+            // the new memory model operations like accidental
+            // synchronization may force any compiler to reload these
+            // fields from memory, destroying their ability to
+            // optimize.
+            float locoef_tmp = locoef;
+            float hicoef_tmp = hicoef;
+            float[] ysinlo_tmp = ysinlo;
+            float[] ysinhi_tmp = ysinhi;
+            float[] ycoslo_tmp = ycoslo;
+            float[] ycoshi_tmp = ycoshi;
+            float[] sinArray_tmp = sinArray;
+            float[] xyArray_tmp = xyArray;
+
+            for(int j = 0; j < STRIP_SIZE; j++) {
+              float y;
+
+              y = xyArray_tmp[j + jOffset];
+
+              float ny;
+
+              v[vertexIndex] = x;
+              v[vertexIndex + 1] = y;
+              v[vertexIndex + 2] = (locoef_tmp * (sinArray_tmp[loXIndex] + ysinlo_tmp[j]) + 
+                                    hicoef_tmp * (sinArray_tmp[hiXIndex] + ysinhi_tmp[j]));
+              n[vertexIndex] = nx;
+              n[vertexIndex + 1] = ny = locoef_tmp * -ycoslo_tmp[j] + hicoef_tmp * -ycoshi_tmp[j];
+              n[vertexIndex + 2] = .15f; //.15f * (1.f - sqrt(nx * nx + ny * ny));
+
+              vertexIndex += 3;
+            }
+            loX.incr();
+            hiX.incr();
+          }
+          loX.reset();
+          hiX.reset();
+
+          // NOTE: we don't make the glVertexPointer/glNormalPointer
+          // call until this point because the semantics in the
+          // "fixed" implementation are that they copy data.
+          gl.glVertexPointer(3, GL_FLOAT, 3 * SIZEOF_FLOAT, v);
+          gl.glNormalPointer(GL_FLOAT, 3 * SIZEOF_FLOAT, n);
+
+          for (int i = 0; i < elements.length; i++) {
+            ++numDrawElementsCalls;
+            gl.glDrawElements(primitive, elements[i].length, GL_UNSIGNED_INT, elements[i]);
+            if(getFlag('f')) {
+              gl.glFlush();
+            }
+          }
+
+	  gl.glSetFenceNV(buffers[cur].fence, GL_ALL_COMPLETED_NV);
+        }
+      }
+
+      gl.glPopMatrix();
+
+      gl.glFinishFenceNV(buffers[cur].fence);
+
+      if (getFlag('r')) {
+        if (!firstProfiledFrame) {
+          if (++profiledFrameCount == 30) {
+            long endTimeMillis = System.currentTimeMillis();
+            double secs = (endTimeMillis - startTimeMillis) / 1000.0;
+            double fps  = 30.0 / secs;
+            double ppf  = tileSize * tileSize * 2;
+            double mpps = ppf * fps / 1000000.0;
+            System.err.println("fps: " + fps + " polys/frame: " + ppf + " million polys/sec: " + mpps +
+                               " DrawElements calls/frame: " + (numDrawElementsCalls / 30));
+            profiledFrameCount = 0;
+            numDrawElementsCalls = 0;
+            startTimeMillis = System.currentTimeMillis();
+          }
+        } else {
+          startTimeMillis = System.currentTimeMillis();
+          firstProfiledFrame = false;
+        
+        }
+      }
+    }
+
+    // Unused routines
+    public void cleanup(GLDrawable drawable) {}
+    public void preDisplay(GLDrawable drawable) {}
+    public void postDisplay(GLDrawable drawable) {}
+    public void reshape(GLDrawable drawable, int width, int height) {}
+  }
+
+  private void allocateBigArray(boolean tryAgain) {
+    float priority = .5f;
+
+    float megabytes = (bufferSize / 1000000.f);
+    try {
+      bigArrayVar = setupBuffer(gl.glAllocateMemoryNV(bufferSize, 0, 0, priority));
+    }
+    catch (OutOfMemoryError e1) {
+      // Try a higher priority
+      try {
+	bigArrayVar = setupBuffer(gl.glAllocateMemoryNV(bufferSize, 0, 0, 1.f));
+      }
+      catch (OutOfMemoryError e2) {
+        if (!tryAgain) {
+          throw new RuntimeException("Unable to allocate " + megabytes +
+                                     " megabytes of fast memory. Giving up.");
+        }
+
+        System.err.println("Unable to allocate " + megabytes +
+                           " megabytes of fast memory. Trying less.");
+        bufferSize /= 2;
+        numBuffers /= 2;
+        allocateBigArray(false);
+        return;
+      }
+    }
+
+    System.err.println("Allocated " + megabytes + " megabytes of fast memory");
+  }
+
+  private FloatBuffer setupBuffer(ByteBuffer buf) {
+    buf.order(ByteOrder.nativeOrder());
+    return buf.asFloatBuffer();
+  }
+
+  private FloatBuffer sliceBuffer(FloatBuffer array,
+                                  int sliceStartIndex, int sliceLength) {
+    array.position(sliceStartIndex);
+    FloatBuffer ret = array.slice();
+    array.position(0);
+    ret.limit(sliceLength);
+    return ret;
+  }
+
+  private void computeElements() {
+    xyArray = new float[tileSize];
+    for (int i = 0; i < tileSize; i++) {
+      xyArray[i] = i / (tileSize - 1.0f) - 0.5f;
+    }
+
+    elements = new int[tileSize - 1][];
+    for (int i = 0; i < tileSize - 1; i++) {
+      elements[i] = new int[2 * STRIP_SIZE];
+      for (int j = 0; j < 2 * STRIP_SIZE; j += 2) {
+        elements[i][j]   =  i      * STRIP_SIZE + (j / 2);
+        elements[i][j+1] = (i + 1) * STRIP_SIZE + (j / 2);
+      }
+    }
+  }
+}