3d-morph.js

//
// Copyright (C) 2007 Apple Inc.  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
//

jsdb_setOption("Math");

var loops = 15;
var nx = 120;
var nz = 120;

function morph(a, f) {
    var PI2nx = Math.PI * 8/nx;
    var sin = Math.sin;
    var f30 = -(50 * sin(f*Math.PI*2));
    
    for (var i = 0; i < nz; ++i) {
        for (var j = 0; j < nx; ++j) {
            a[3*(i*nx+j)+1]    = sin((j-1) * PI2nx ) * -f30;
        }
    }
}

    
var a = Array(nx*nz*3);

for (var i=0; i < nx*nz*3; ++i) 
    a[i] = 0;

for (var i = 0; i < loops; ++i) {
    morph(a, i/loops);
}

var testOutput = 0;

for (var i = 0; i < nx; i++)
    testOutput += a[3*(i*nx+i)+1];

a = null;

// This has to be an approximate test since ECMAscript doesn't formally specify
// what sin() returns. Even if it did specify something like for example what Java 7
// says - that sin() has to return a value within 1 ulp of exact - then we still
// would not be able to do an exact test here since that would allow for just enough
// low-bit slop to create possibly big errors due to testOutput being a sum.

var epsilon = 1e-13;

if (Math.abs(testOutput) >= epsilon)
    print("Error: bad test output: expected magnitude below " + epsilon + " but got " + testOutput);
else
	print("Success: ", testOutput);