// generateDrawIndexBuffer(..)
//
// Walks the wavefront faces, feeds pre-configured verticies to the VertexSoup,
// and returns a new index-buffer pointing to the new VertexSoup.verticies indicies.
public static void generateDrawIndexBuffer(
WavefrontObjLoader wff,
out UInt16[] indicies_return,
out SSVertex_PosNormDiffTex1[] verticies_return)
{
const bool shouldDedup = true; // this lets us turn on/of vertex-soup deduping
var soup = new VertexSoup<SSVertex_PosNormDiffTex1>(deDup:shouldDedup);
List<UInt16> draw_indicies = new List<UInt16>();
// (0) go throu`gh the materials and faces, DENORMALIZE from WF-OBJ into fully-configured verticies
// load indexes
foreach (var mtl in wff.materials) {
// wavefrontOBJ stores color in CIE-XYZ color space. Convert this to Alpha-RGB
var materialDiffuseColor = WavefrontObjLoader.CIEXYZtoColor(mtl.vDiffuse).ToArgb();
foreach (var face in mtl.faces) {
// iterate over the vericies of a wave-front FACE...
// DEREFERENCE each .obj vertex paramater (position, normal, texture coordinate)
SSVertex_PosNormDiffTex1[] vertex_list = new SSVertex_PosNormDiffTex1[face.v_idx.Length];
for (int facevertex = 0; facevertex < face.v_idx.Length; facevertex++) {
// position
vertex_list[facevertex].Position = CV(wff.positions[face.v_idx[facevertex]]);
// normal
int normal_idx = face.n_idx[facevertex];
if (normal_idx != -1) {
vertex_list[facevertex].Normal = CV(wff.normals[normal_idx]);
}
// texture coordinate
int tex_index = face.tex_idx[facevertex];
if (tex_index != -1 ) {
vertex_list[facevertex].Tu = wff.texCoords[tex_index].U;
vertex_list[facevertex].Tv = 1- wff.texCoords[tex_index].V;
}
// assign our material's diffusecolor to the vertex diffuse color...
vertex_list [facevertex].DiffuseColor = materialDiffuseColor;
}
// turn them into indicies in the vertex soup..
// .. we hand the soup a set of fully configured verticies. It
// .. dedups and accumulates them, and hands us back indicies
// .. relative to it's growing list of deduped verticies.
UInt16[] soup_indicies = soup.digestVerticies(vertex_list);
// now we add these indicies to the draw-list. Right now we assume
// draw is using GL_TRIANGLE, so we convert NGONS into triange lists
if (soup_indicies.Length == 3) { // triangle
draw_indicies.Add(soup_indicies[0]);
draw_indicies.Add(soup_indicies[1]);
draw_indicies.Add(soup_indicies[2]);
} else if (soup_indicies.Length == 4) { // quad
draw_indicies.Add(soup_indicies[0]);
draw_indicies.Add(soup_indicies[1]);
draw_indicies.Add(soup_indicies[2]);
draw_indicies.Add(soup_indicies[0]);
draw_indicies.Add(soup_indicies[2]);
draw_indicies.Add(soup_indicies[3]);
} else {
// This n-gon algorithm only works if the n-gon is coplanar and convex,
// which Wavefront OBJ says they must be.
// .. to tesselate concave ngons, one must tesselate using a more complex method, see
// http://en.wikipedia.org/wiki/Polygon_triangulation#Ear_clipping_method
// manually generate a triangle-fan
for (int x = 1; x < (soup_indicies.Length-1); x++) {
draw_indicies.Add(soup_indicies[0]);
draw_indicies.Add(soup_indicies[x]);
draw_indicies.Add(soup_indicies[x+1]);
}
// throw new NotImplementedException("unhandled face size: " + newindicies.Length);
}
}
}
// convert the linked-lists into arrays and return
indicies_return = draw_indicies.ToArray();
verticies_return = soup.verticies.ToArray();
Console.WriteLine ("VertexSoup_VertexFormatBinder:generateDrawIndexBuffer : \r\n {0} verticies, {1} indicies. Dedup = {2}",
verticies_return.Length, indicies_return.Length,
shouldDedup ? "YES" : "NO");
}
private static Vector3 CV(WavefrontObjLoader.Vector_XYZ dxv)
{
return new Vector3(dxv.X, dxv.Y, dxv.Z);
}