assimp/tools/assimp_view/MeshRenderer.cpp

/*
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Open Asset Import Library (assimp)
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*/

#include "assimp_view.h"

#include <map>
#include <functional>

namespace AssimpView {

CMeshRenderer CMeshRenderer::s_cInstance;

//-------------------------------------------------------------------------------
int CMeshRenderer::DrawUnsorted(unsigned int iIndex)
{
	ai_assert(iIndex < g_pcAsset->pcScene->mNumMeshes);

	// set vertex and index buffer
	g_piDevice->SetStreamSource(0,g_pcAsset->apcMeshes[iIndex]->piVB,0,
		sizeof(AssetHelper::Vertex));

	g_piDevice->SetIndices(g_pcAsset->apcMeshes[iIndex]->piIB);

	D3DPRIMITIVETYPE type = D3DPT_POINTLIST;
	switch (g_pcAsset->pcScene->mMeshes[iIndex]->mPrimitiveTypes) {
		case aiPrimitiveType_POINT:
			type = D3DPT_POINTLIST;break;
		case aiPrimitiveType_LINE:
			type = D3DPT_LINELIST;break;
		case aiPrimitiveType_TRIANGLE:
			type = D3DPT_TRIANGLELIST;break;
	}
	// and draw the mesh
	g_piDevice->DrawIndexedPrimitive(type,
		0,0,
		g_pcAsset->pcScene->mMeshes[iIndex]->mNumVertices,0,
		g_pcAsset->pcScene->mMeshes[iIndex]->mNumFaces);

	return 1;
}
//-------------------------------------------------------------------------------
int CMeshRenderer::DrawSorted(unsigned int iIndex,const aiMatrix4x4& mWorld)
{
	ai_assert(iIndex < g_pcAsset->pcScene->mNumMeshes);

	AssetHelper::MeshHelper* pcHelper = g_pcAsset->apcMeshes[iIndex]; 
	const aiMesh* pcMesh = g_pcAsset->pcScene->mMeshes[iIndex];

	if (!pcHelper || !pcMesh || !pcHelper->piIB)
		return -5;

	if (pcMesh->mPrimitiveTypes != aiPrimitiveType_TRIANGLE || pcMesh->HasBones() || g_sOptions.bNoAlphaBlending)
		return DrawUnsorted(iIndex);


	// compute the position of the camera in worldspace
	aiMatrix4x4 mWorldInverse = mWorld;
	mWorldInverse.Inverse();
	mWorldInverse.Transpose();
	const aiVector3D vLocalCamera = mWorldInverse * g_sCamera.vPos;

	// well ... this is really funny now. We must compute their distance
	// from the camera. We take the average distance of a face and add it 
	// to a map which sorts it
	std::map<float,unsigned int, std::greater<float> > smap;

	for (unsigned int iFace = 0; iFace < pcMesh->mNumFaces;++iFace)
	{
		const aiFace* pcFace = &pcMesh->mFaces[iFace];
		float fDist = 0.0f;
		for (unsigned int c = 0; c < 3;++c)
		{
			aiVector3D vPos = pcMesh->mVertices[pcFace->mIndices[c]];
			vPos -= vLocalCamera;
			fDist += vPos.SquareLength();
		}
		smap.insert(std::pair<float, unsigned int>(fDist,iFace));
	}

	// now we can lock the index buffer and rebuild it
	D3DINDEXBUFFER_DESC sDesc;
	pcHelper->piIB->GetDesc(&sDesc);

	if (D3DFMT_INDEX16 == sDesc.Format)
	{
		uint16_t* aiIndices;
		pcHelper->piIB->Lock(0,0,(void**)&aiIndices,D3DLOCK_DISCARD);

		for (std::map<float,unsigned int, std::greater<float> >::const_iterator
			i =  smap.begin();
			i != smap.end();++i)
		{
			const aiFace* pcFace =  &pcMesh->mFaces[(*i).second];
			*aiIndices++ = (uint16_t)pcFace->mIndices[0];
			*aiIndices++ = (uint16_t)pcFace->mIndices[1];
			*aiIndices++ = (uint16_t)pcFace->mIndices[2];
		}
	}
	else if (D3DFMT_INDEX32 == sDesc.Format)
	{
		uint32_t* aiIndices;
		pcHelper->piIB->Lock(0,0,(void**)&aiIndices,D3DLOCK_DISCARD);

		for (std::map<float,unsigned int, std::greater<float> >::const_iterator
			i =  smap.begin();
			i != smap.end();++i)
		{
			const aiFace* pcFace =  &pcMesh->mFaces[(*i).second];
			*aiIndices++ = (uint32_t)pcFace->mIndices[0];
			*aiIndices++ = (uint32_t)pcFace->mIndices[1];
			*aiIndices++ = (uint32_t)pcFace->mIndices[2];
		}
	}
	pcHelper->piIB->Unlock();

	// set vertex and index buffer
	g_piDevice->SetStreamSource(0,pcHelper->piVB,0,sizeof(AssetHelper::Vertex));

	// and draw the mesh
	g_piDevice->SetIndices(pcHelper->piIB);
	g_piDevice->DrawIndexedPrimitive(D3DPT_TRIANGLELIST,
		0,0,
		pcMesh->mNumVertices,0,
		pcMesh->mNumFaces);

	return 1;
}
};