/// <summary>
/// Function to remap your indices to improve spatial locality in your vertex buffer.
/// </summary>
/// <remarks>
/// Note that, according to the remapping handed back to you, you must reorder your
/// vertex buffer.
/// </remarks>
/// <param name="primitiveGroups">Array of PrimitiveGroups you want remapped.</param>
/// <param name="vertexCount">
/// Number of vertices in your vertex buffer, also can be thought of as the range of acceptable
/// values for indices in your primitive groups.
/// </param>
/// <param name="remappedPrimitiveGroups">Array of remapped PrimitiveGroups.</param>
public void RemapIndices(PrimitiveGroup[] primitiveGroups, ushort vertexCount,
out PrimitiveGroup[] remappedPrimitiveGroups)
{
remappedPrimitiveGroups = new PrimitiveGroup[primitiveGroups.Length];
//caches oldIndex --> newIndex conversion
var indexCache = new int[vertexCount];
for (int i = 0; i < indexCache.Length; ++i)
{
indexCache[i] = -1;
}
//loop over primitive groups
uint indexCtr = 0;
for (int i = 0; i < primitiveGroups.Length; i++)
{
int numIndices = primitiveGroups[i].Indices.Length;
//init remapped group
remappedPrimitiveGroups[i] =
new PrimitiveGroup(primitiveGroups[i].Type, new ushort[numIndices]);
for (int j = 0; j < numIndices; j++)
{
int cachedIndex = indexCache[primitiveGroups[i].Indices[j]];
if (cachedIndex == -1) //we haven't seen this index before
{
//point to "last" vertex in VB
remappedPrimitiveGroups[i].Indices[j] = ( ushort )indexCtr;
//add to index cache, increment
indexCache[primitiveGroups[i].Indices[j]] = ( ushort )indexCtr++;
}
else
{
//we've seen this index before
remappedPrimitiveGroups[i].Indices[j] = ( ushort )cachedIndex;
}
}
}
}
/// <summary>
/// Generates strips from the given input indices.
/// </summary>
/// <param name="indices">Input index list, the indices you would use to render.</param>
/// <param name="primitiveGroups">Array of optimized/stripified PrimitiveGroups</param>
/// <param name="validateEnabled">Whether to validate the output or not.</param>
/// <returns>A boolean indicating whether the operation completed successfully.</returns>
public bool GenerateStrips(ushort[] indices, out PrimitiveGroup[] primitiveGroups, bool validateEnabled = false)
{
var numGroups = 0;
//put data in format that the stripifier likes
var tempIndices = new List <ushort>(indices.Length);
ushort maxIndex = 0;
ushort minIndex = 0xFFFF;
for (var i = 0; i < indices.Length; i++)
{
tempIndices.Add(indices[i]);
if (indices[i] > maxIndex)
{
maxIndex = indices[i];
}
if (indices[i] < minIndex)
{
minIndex = indices[i];
}
}
var tempStrips = new List <StripInfo>();
var tempFaces = new List <FaceInfo>();
var stripifier = new Stripifier();
//do actual stripification
stripifier.Stripify(tempIndices, CacheSize, MinStripSize, maxIndex, tempStrips, tempFaces);
//stitch strips together
var stripIndices = new List <int>();
uint numSeparateStrips = 0;
if (ListsOnly)
{
//if we're outputting only lists, we're done
numGroups = 1;
primitiveGroups = new PrimitiveGroup[numGroups];
var primGroupArray = primitiveGroups;
//count the total number of indices
uint numIndices = 0;
for (var i = 0; i < tempStrips.Count; i++)
{
numIndices += ( uint )(tempStrips[i].Faces.Count * 3);
}
//add in the list
numIndices += ( uint )(tempFaces.Count * 3);
primGroupArray[0] = new PrimitiveGroup(PrimitiveType.TriangleList, new ushort[numIndices]);
//do strips
uint indexCtr = 0;
for (var i = 0; i < tempStrips.Count; i++)
{
for (var j = 0; j < tempStrips[i].Faces.Count; j++)
{
//degenerates are of no use with lists
if (!Stripifier.IsDegenerate(tempStrips[i].Faces[j]))
{
primGroupArray[0].Indices[indexCtr++] = ( ushort )tempStrips[i].Faces[j].V0;
primGroupArray[0].Indices[indexCtr++] = ( ushort )tempStrips[i].Faces[j].V1;
primGroupArray[0].Indices[indexCtr++] = ( ushort )tempStrips[i].Faces[j].V2;
}
else
{
//we've removed a tri, reduce the number of indices
var resizedIndices = primGroupArray[0].Indices;
Array.Resize(ref resizedIndices, primGroupArray[0].Indices.Length - 3);
primGroupArray[0].Indices = resizedIndices;
}
}
}
//do lists
for (var i = 0; i < tempFaces.Count; i++)
{
primGroupArray[0].Indices[indexCtr++] = ( ushort )tempFaces[i].V0;
primGroupArray[0].Indices[indexCtr++] = ( ushort )tempFaces[i].V1;
primGroupArray[0].Indices[indexCtr++] = ( ushort )tempFaces[i].V2;
}
}
else
{
stripifier.CreateStrips(tempStrips, stripIndices, StitchStrips, ref numSeparateStrips, UseRestart, ( uint )RestartValue);
//if we're stitching strips together, we better get back only one strip from CreateStrips()
Debug.Assert(StitchStrips && numSeparateStrips == 1 || !StitchStrips);
//convert to output format
numGroups = ( ushort )numSeparateStrips; //for the strips
if (tempFaces.Count != 0)
{
numGroups++; //we've got a list as well, increment
}
primitiveGroups = new PrimitiveGroup[numGroups];
var primGroupArray = primitiveGroups;
//first, the strips
var startingLoc = 0;
for (var stripCtr = 0; stripCtr < numSeparateStrips; stripCtr++)
{
var stripLength = 0;
if (!StitchStrips)
{
//if we've got multiple strips, we need to figure out the correct length
int i;
for (i = startingLoc; i < stripIndices.Count; i++)
{
if (stripIndices[i] == -1)
{
break;
}
}
stripLength = i - startingLoc;
}
else
{
stripLength = stripIndices.Count;
}
primGroupArray[stripCtr] = new PrimitiveGroup(PrimitiveType.TriangleStrip, new ushort[stripLength]);
var indexCtr = 0;
for (int i = startingLoc; i < stripLength + startingLoc; i++)
{
primGroupArray[stripCtr].Indices[indexCtr++] = ( ushort )stripIndices[i];
}
//we add 1 to account for the -1 separating strips
//this doesn't break the stitched case since we'll exit the loop
startingLoc += stripLength + 1;
}
//next, the list
if (tempFaces.Count != 0)
{
int faceGroupLoc = numGroups - 1; //the face group is the last one
primGroupArray[faceGroupLoc] = new PrimitiveGroup(PrimitiveType.TriangleList, new ushort[tempFaces.Count * 3]);
var indexCtr = 0;
for (var i = 0; i < tempFaces.Count; i++)
{
primGroupArray[faceGroupLoc].Indices[indexCtr++] = ( ushort )tempFaces[i].V0;
primGroupArray[faceGroupLoc].Indices[indexCtr++] = ( ushort )tempFaces[i].V1;
primGroupArray[faceGroupLoc].Indices[indexCtr++] = ( ushort )tempFaces[i].V2;
}
}
}
//validate generated data against input
if (validateEnabled)
{
var numbins = 100;
var inBins = new List <FaceInfo> [numbins];
for (var i = 0; i < inBins.Length; ++i)
{
inBins[i] = new List <FaceInfo>();
}
//hash input indices on first index
for (var i = 0; i < indices.Length; i += 3)
{
var faceInfo = new FaceInfo(indices[i], indices[i + 1], indices[i + 2]);
inBins[indices[i] % numbins].Add(faceInfo);
}
for (var i = 0; i < numGroups; ++i)
{
switch (primitiveGroups[i].Type)
{
case PrimitiveType.TriangleList:
{
for (var j = 0; j < primitiveGroups[i].Indices.Length; j += 3)
{
ushort v0 = primitiveGroups[i].Indices[j];
ushort v1 = primitiveGroups[i].Indices[j + 1];
ushort v2 = primitiveGroups[i].Indices[j + 2];
//ignore degenerates
if (Stripifier.IsDegenerate(v0, v1, v2))
{
continue;
}
if (!TestTriangle(v0, v1, v2, inBins, numbins))
{
Cleanup(tempStrips, tempFaces);
return(false);
}
}
break;
}
case PrimitiveType.TriangleStrip:
{
var flip = false;
for (var j = 2; j < primitiveGroups[i].Indices.Length; ++j)
{
ushort v0 = primitiveGroups[i].Indices[j - 2];
ushort v1 = primitiveGroups[i].Indices[j - 1];
ushort v2 = primitiveGroups[i].Indices[j];
if (flip)
{
//swap v1 and v2
ushort swap = v1;
v1 = v2;
v2 = swap;
}
//ignore degenerates
if (Stripifier.IsDegenerate(v0, v1, v2))
{
flip = !flip;
continue;
}
if (!TestTriangle(v0, v1, v2, inBins, numbins))
{
Cleanup(tempStrips, tempFaces);
return(false);
}
flip = !flip;
}
break;
}
case PrimitiveType.TriangleFan:
default:
break;
}
}
}
//clean up everything
Cleanup(tempStrips, tempFaces);
return(true);
}