ShadowEditor/THREE/Math/Interpolant.cs
2018-12-08 07:44:06 +08:00

263 lines
6.5 KiB
C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace THREE
{
public class Interpolant
{
function Interpolant(parameterPositions, sampleValues, sampleSize, resultBuffer )
{
this.parameterPositions = parameterPositions;
this._cachedIndex = 0;
this.resultBuffer = resultBuffer !== undefined ?
resultBuffer : new sampleValues.constructor(sampleSize);
this.sampleValues = sampleValues;
this.valueSize = sampleSize;
}
evaluate: function(t )
{
var pp = this.parameterPositions,
i1 = this._cachedIndex,
t1 = pp[i1],
t0 = pp[i1 - 1];
validate_interval:
{
seek:
{
var right;
linear_scan:
{
//- See http://jsperf.com/comparison-to-undefined/3
//- slower code:
//-
//- if ( t >= t1 || t1 === undefined ) {
forward_scan: if (!(t < t1))
{
for (var giveUpAt = i1 + 2; ;)
{
if (t1 === undefined)
{
if (t < t0) break forward_scan;
// after end
i1 = pp.length;
this._cachedIndex = i1;
return this.afterEnd_(i1 - 1, t, t0);
}
if (i1 === giveUpAt) break; // this loop
t0 = t1;
t1 = pp[++i1];
if (t < t1)
{
// we have arrived at the sought interval
break seek;
}
}
// prepare binary search on the right side of the index
right = pp.length;
break linear_scan;
}
//- slower code:
//- if ( t < t0 || t0 === undefined ) {
if (!(t >= t0))
{
// looping?
var t1global = pp[1];
if (t < t1global)
{
i1 = 2; // + 1, using the scan for the details
t0 = t1global;
}
// linear reverse scan
for (var giveUpAt = i1 - 2; ;)
{
if (t0 === undefined)
{
// before start
this._cachedIndex = 0;
return this.beforeStart_(0, t, t1);
}
if (i1 === giveUpAt) break; // this loop
t1 = t0;
t0 = pp[--i1 - 1];
if (t >= t0)
{
// we have arrived at the sought interval
break seek;
}
}
// prepare binary search on the left side of the index
right = i1;
i1 = 0;
break linear_scan;
}
// the interval is valid
break validate_interval;
} // linear scan
// binary search
while (i1 < right)
{
var mid = (i1 + right) >>> 1;
if (t < pp[mid])
{
right = mid;
}
else
{
i1 = mid + 1;
}
}
t1 = pp[i1];
t0 = pp[i1 - 1];
// check boundary cases, again
if (t0 === undefined)
{
this._cachedIndex = 0;
return this.beforeStart_(0, t, t1);
}
if (t1 === undefined)
{
i1 = pp.length;
this._cachedIndex = i1;
return this.afterEnd_(i1 - 1, t0, t);
}
} // seek
this._cachedIndex = i1;
this.intervalChanged_(i1, t0, t1);
} // validate_interval
return this.interpolate_(i1, t0, t, t1);
},
settings: null, // optional, subclass-specific settings structure
// Note: The indirection allows central control of many interpolants.
// --- Protected interface
DefaultSettings_: {},
getSettings_: function()
{
return this.settings || this.DefaultSettings_;
},
copySampleValue_: function(index )
{
// copies a sample value to the result buffer
var result = this.resultBuffer,
values = this.sampleValues,
stride = this.valueSize,
offset = index * stride;
for (var i = 0; i !== stride; ++i)
{
result[i] = values[offset + i];
}
return result;
},
// Template methods for derived classes:
interpolate_: function( /* i1, t0, t, t1 */ )
{
throw new Error('call to abstract method');
// implementations shall return this.resultBuffer
},
intervalChanged_: function( /* i1, t0, t1 */ )
{
// empty
}
//( 0, t, t0 ), returns this.resultBuffer
beforeStart_: Interpolant.prototype.copySampleValue_,
//( N-1, tN-1, t ), returns this.resultBuffer
afterEnd_: Interpolant.prototype.copySampleValue_,
}
}