3d-morph.js 2.4 KB

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  1. /*
  2. * Copyright (C) 2007 Apple Inc. All rights reserved.
  3. *
  4. * Redistribution and use in source and binary forms, with or without
  5. * modification, are permitted provided that the following conditions
  6. * are met:
  7. * 1. Redistributions of source code must retain the above copyright
  8. * notice, this list of conditions and the following disclaimer.
  9. * 2. Redistributions in binary form must reproduce the above copyright
  10. * notice, this list of conditions and the following disclaimer in the
  11. * documentation and/or other materials provided with the distribution.
  12. *
  13. * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14. * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16. * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
  17. * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18. * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19. * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20. * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21. * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22. * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23. * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24. */
  25. var loops = 15
  26. var nx = 120
  27. var nz = 120
  28. function morph(a, f) {
  29. var PI2nx = Math.PI * 8/nx
  30. var sin = Math.sin
  31. var f30 = -(50 * sin(f*Math.PI*2))
  32. for (var i = 0; i < nz; ++i) {
  33. for (var j = 0; j < nx; ++j) {
  34. a[3*(i*nx+j)+1] = sin((j-1) * PI2nx ) * -f30
  35. }
  36. }
  37. }
  38. var a = Array()
  39. for (var i=0; i < nx*nz*3; ++i)
  40. a[i] = 0
  41. for (var i = 0; i < loops; ++i) {
  42. morph(a, i/loops)
  43. }
  44. testOutput = 0;
  45. for (var i = 0; i < nx; i++)
  46. testOutput += a[3*(i*nx+i)+1];
  47. a = null;
  48. // This has to be an approximate test since ECMAscript doesn't formally specify
  49. // what sin() returns. Even if it did specify something like for example what Java 7
  50. // says - that sin() has to return a value within 1 ulp of exact - then we still
  51. // would not be able to do an exact test here since that would allow for just enough
  52. // low-bit slop to create possibly big errors due to testOutput being a sum.
  53. var epsilon = 1e-13;
  54. if (Math.abs(testOutput) >= epsilon)
  55. throw "Error: bad test output: expected magnitude below " + epsilon + " but got " + testOutput;