/**
* This method triangulates the faces if they are given as a polylist. Does nothing in case the
* faces are given as triangles already.
*
* @param polyList
*/
private void triangulate(Element polyList) {
if (!polyList.getName().equals("polylist")) return;
Element colladaPolys = polyList.getChildByName("vcount");
if (colladaPolys == null)
throw new GdxRuntimeException("<polylist> does not contain <vcount> element");
String[] tokens = colladaPolys.getText().split("\\s+");
int[] polys = new int[tokens.length];
int vertexCount = 0;
for (int i = 0; i < tokens.length; i++) {
int verts = Integer.parseInt(tokens[i]);
polys[i] = verts;
vertexCount += verts;
}
Array<VertexIndices> newVertices = new Array<VertexIndices>(vertexCount);
int idx = 0;
for (int i = 0; i < polys.length; i++) {
int numVertices = polys[i];
VertexIndices baseVertex = triangles.get(idx++);
for (int j = 1; j < numVertices - 1; j++) {
newVertices.add(baseVertex);
newVertices.add(triangles.get(idx));
newVertices.add(triangles.get(idx + 1));
idx++;
}
idx++;
}
triangles = newVertices;
}
/**
* Conditions the inputs for a triangles/polylist list of faces and generates unique vertices
* while merging duplicate vertices.
*
* @param faces
*/
private void parseVertices(Element faces) {
inputs = faces.getChildrenByName("input");
if (inputs == null)
throw new GdxRuntimeException("no <input> elements in <triangles>/<polylist>");
int[] offsets = new int[inputs.size];
int stride = 0;
// normalize source references, should use the URI/address scheme of Collada FIXME
// calculate stride and prepare to untangle the index lists mess...
sources = new Source[inputs.size];
for (int i = 0; i < inputs.size; i++) {
Element input = inputs.get(i);
// map source if it was defined in <vertices> tag
String source = input.getAttribute("source").substring(1);
if (mappings.containsKey(source)) {
input.setAttribute("source", mappings.get(source));
} else {
input.setAttribute("source", source);
}
// check whether source exists
source = input.getAttribute("source");
if (!sourcesMap.containsKey(source))
throw new GdxRuntimeException("source '" + source + "' not in mesh> but in <triangle>");
sources[i] = sourcesMap.get(source);
offsets[i] = Integer.parseInt(input.getAttribute("offset"));
stride = Math.max(offsets[i], stride);
}
// addjust for zero source offsets
stride += 1;
// parse <p> indices, yeah, that takes up a bit more memory.
String[] tokens = faces.getChildByName("p").getText().split("\\s+");
int[] indices = new int[tokens.length];
for (int i = 0; i < tokens.length; i++) {
indices[i] = Integer.parseInt(tokens[i]);
}
// untangle indices on a per source basis
Map<VertexIndices, VertexIndices> indicesSet = new HashMap<VertexIndices, VertexIndices>();
VertexIndices vertex = new VertexIndices(inputs.size);
triangles = new Array<VertexIndices>(indices.length / stride);
vertices = new Array<VertexIndices>(indices.length / stride);
int index = 0;
for (int i = 0; i < indices.length; i += stride) {
for (int j = 0; j < inputs.size; j++) {
vertex.indices[j] = indices[i + offsets[j]];
vertex.index = index;
}
VertexIndices lookup = indicesSet.get(vertex);
if (lookup != null) {
triangles.add(lookup);
} else {
triangles.add(vertex);
vertices.add(vertex);
indicesSet.put(vertex, vertex);
vertex = new VertexIndices(inputs.size);
index++;
}
}
numVertices = index;
}