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Merge pull request #586 from Talon1024/feature/objSmoothCalc
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Calculate normals for OBJ models with smooth groups
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@dpjudas
dpjudas committed Oct 5, 2018
2 parents 8ea7477 + 525ab8e commit d4a6428
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Showing 2 changed files with 152 additions and 26 deletions.
157 changes: 133 additions & 24 deletions src/r_data/models/models_obj.cpp
View file
Expand Up @@ -101,8 +101,9 @@ bool FOBJModel::Load(const char* fn, int lumpnum, const char* buffer, int length

FTextureID curMtl = FNullTextureID();
OBJSurface *curSurface = nullptr;
int aggSurfFaceCount = 0;
int curSurfFaceCount = 0;
unsigned int aggSurfFaceCount = 0;
unsigned int curSurfFaceCount = 0;
unsigned int curSmoothGroup = 0;

while(sc.GetString())
{
Expand Down Expand Up @@ -186,9 +187,25 @@ bool FOBJModel::Load(const char* fn, int lumpnum, const char* buffer, int length
sc.UnGet(); // No 4th side, move back
}
}
face.smoothGroup = curSmoothGroup;
faces.Push(face);
curSurfFaceCount += 1;
}
else if (sc.Compare("s"))
{
sc.MustGetString();
if (sc.Compare("off"))
{
curSmoothGroup = 0;
}
else
{
sc.UnGet();
sc.MustGetNumber();
curSmoothGroup = sc.Number;
hasSmoothGroups = hasSmoothGroups || curSmoothGroup > 0;
}
}
}
sc.Close();

Expand Down Expand Up @@ -277,18 +294,21 @@ bool FOBJModel::ParseFaceSide(const FString &sideStr, OBJFace &face, int sidx)
else
{
side.normref = -1;
hasMissingNormals = true;
}
}
else
{
side.normref = -1;
hasMissingNormals = true;
}
}
else
{
origIdx = atoi(sideStr.GetChars());
side.vertref = ResolveIndex(origIdx, FaceElement::VertexIndex);
side.normref = -1;
hasMissingNormals = true;
side.uvref = -1;
}
face.sides[sidx] = side;
Expand Down Expand Up @@ -348,15 +368,20 @@ void FOBJModel::BuildVertexBuffer(FModelRenderer *renderer)
surfaces[i].vbStart = vbufsize;
vbufsize += surfaces[i].numTris * 3;
}
// Initialize/populate vertFaces
if (hasMissingNormals && hasSmoothGroups)
{
AddVertFaces();
}

auto vbuf = renderer->CreateVertexBuffer(false,true);
SetVertexBuffer(renderer, vbuf);

FModelVertex *vertptr = vbuf->LockVertexBuffer(vbufsize);

for (size_t i = 0; i < surfaces.Size(); i++)
for (unsigned int i = 0; i < surfaces.Size(); i++)
{
for (size_t j = 0; j < surfaces[i].numTris; j++)
for (unsigned int j = 0; j < surfaces[i].numTris; j++)
{
for (size_t side = 0; side < 3; side++)
{
Expand All @@ -372,39 +397,40 @@ void FOBJModel::BuildVertexBuffer(FModelRenderer *renderer)

FVector3 curVvec = RealignVector(verts[vidx]);
FVector2 curUvec = FixUV(uvs[uvidx]);
FVector3 *nvec = nullptr;
FVector3 nvec;

mdv->Set(curVvec.X, curVvec.Y, curVvec.Z, curUvec.X, curUvec.Y);

if (nidx >= 0 && (unsigned int)nidx < norms.Size())
{
nvec = new FVector3(RealignVector(norms[nidx]));
nvec = RealignVector(norms[nidx]);
}
else
{
// https://www.khronos.org/opengl/wiki/Calculating_a_Surface_Normal
// Find other sides of triangle
auto nextSidx = side + 2;
if (nextSidx >= 3) nextSidx -= 3;

auto lastSidx = side + 1;
if (lastSidx >= 3) lastSidx -= 3;

OBJFaceSide &nextSide = surfaces[i].tris[j].sides[nextSidx];
OBJFaceSide &lastSide = surfaces[i].tris[j].sides[lastSidx];

// Cross-multiply the U-vector and V-vector
FVector3 uvec = RealignVector(verts[nextSide.vertref]) - curVvec;
FVector3 vvec = RealignVector(verts[lastSide.vertref]) - curVvec;

nvec = new FVector3(uvec ^ vvec);
if (surfaces[i].tris[j].smoothGroup == 0)
{
nvec = CalculateNormalFlat(i, j);
}
else
{
nvec = CalculateNormalSmooth(vidx, surfaces[i].tris[j].smoothGroup);
}
}
mdv->SetNormal(nvec->X, nvec->Y, nvec->Z);
delete nvec;
mdv->SetNormal(nvec.X, nvec.Y, nvec.Z);
}
}
delete[] surfaces[i].tris;
}

// Destroy vertFaces
if (hasMissingNormals && hasSmoothGroups)
{
for (size_t i = 0; i < verts.Size(); i++)
{
vertFaces[i].Clear();
}
delete[] vertFaces;
}
vbuf->UnlockVertexBuffer();
}

Expand Down Expand Up @@ -432,6 +458,7 @@ void FOBJModel::ConstructSurfaceTris(OBJSurface &surf)
surf.tris[triIdx].sideCount = 3;
if (faces[i].sideCount == 3)
{
surf.tris[triIdx].smoothGroup = faces[i].smoothGroup;
memcpy(surf.tris[triIdx].sides, faces[i].sides, sizeof(OBJFaceSide) * 3);
}
else if (faces[i].sideCount == 4) // Triangulate face
Expand All @@ -443,6 +470,7 @@ void FOBJModel::ConstructSurfaceTris(OBJSurface &surf)
delete[] triangulated;
triIdx += 1; // Filling out two faces
}
DPrintf(DMSG_SPAMMY, "Smooth group: %d\n", surf.tris[triIdx].smoothGroup);
}
}

Expand All @@ -455,7 +483,9 @@ void FOBJModel::ConstructSurfaceTris(OBJSurface &surf)
void FOBJModel::TriangulateQuad(const OBJFace &quad, OBJFace *tris)
{
tris[0].sideCount = 3;
tris[0].smoothGroup = quad.smoothGroup;
tris[1].sideCount = 3;
tris[1].smoothGroup = quad.smoothGroup;

int tsidx[2][3] = {{0, 1, 3}, {1, 2, 3}};

Expand All @@ -470,6 +500,26 @@ void FOBJModel::TriangulateQuad(const OBJFace &quad, OBJFace *tris)
}
}

/**
* Add the vertices of all surfaces' triangles to the array of vertex->triangle references
*/
void FOBJModel::AddVertFaces() {
// Initialize and populate vertFaces - this array stores references to triangles per vertex
vertFaces = new TArray<OBJTriRef>[verts.Size()];
for (unsigned int i = 0; i < surfaces.Size(); i++)
{
for (unsigned int j = 0; j < surfaces[i].numTris; j++)
{
OBJTriRef otr = OBJTriRef(i, j);
for (size_t k = 0; k < surfaces[i].tris[j].sideCount; k++)
{
int vidx = surfaces[i].tris[j].sides[k].vertref;
vertFaces[vidx].Push(otr);
}
}
}
}

/**
* Re-align a vector to match MD3 alignment
*
Expand All @@ -494,6 +544,65 @@ inline FVector2 FOBJModel::FixUV(FVector2 vecToRealign)
return vecToRealign;
}

/**
* Calculate the surface normal for a triangle
*
* @param surfIdx The surface index
* @param triIdx The triangle Index
* @return The surface normal vector
*/
FVector3 FOBJModel::CalculateNormalFlat(unsigned int surfIdx, unsigned int triIdx)
{
// https://www.khronos.org/opengl/wiki/Calculating_a_Surface_Normal
int curVert = surfaces[surfIdx].tris[triIdx].sides[0].vertref;
int nextVert = surfaces[surfIdx].tris[triIdx].sides[2].vertref;
int lastVert = surfaces[surfIdx].tris[triIdx].sides[1].vertref;

// Cross-multiply the U-vector and V-vector
FVector3 curVvec = RealignVector(verts[curVert]);
FVector3 uvec = RealignVector(verts[nextVert]) - curVvec;
FVector3 vvec = RealignVector(verts[lastVert]) - curVvec;

return uvec ^ vvec;
}

/**
* Calculate the surface normal for a triangle
*
* @param otr A reference to the surface, and a triangle within that surface, as an OBJTriRef
* @return The surface normal vector
*/
FVector3 FOBJModel::CalculateNormalFlat(OBJTriRef otr)
{
return CalculateNormalFlat(otr.surf, otr.tri);
}

/**
* Calculate the normal of a vertex in a specific smooth group
*
* @param vidx The index of the vertex in the array of vertices
* @param smoothGroup The smooth group number
*/
FVector3 FOBJModel::CalculateNormalSmooth(unsigned int vidx, unsigned int smoothGroup)
{
unsigned int connectedFaces = 0;
TArray<OBJTriRef>& vTris = vertFaces[vidx];

FVector3 vNormal(0,0,0);
for (size_t face = 0; face < vTris.Size(); face++)
{
OBJFace& tri = surfaces[vTris[face].surf].tris[vTris[face].tri];
if (tri.smoothGroup == smoothGroup)
{
FVector3 fNormal = CalculateNormalFlat(vTris[face]);
connectedFaces += 1;
vNormal += fNormal;
}
}
vNormal /= (float)connectedFaces;
return vNormal;
}

/**
* Find the index of the frame with the given name
*
Expand Down
21 changes: 19 additions & 2 deletions src/r_data/models/models_obj.h
View file
Expand Up @@ -30,6 +30,8 @@ class FOBJModel : public FModel
{
private:
const char *newSideSep = "$"; // OBJ side separator is /, which is parsed as a line comment by FScanner if two of them are next to each other.
bool hasMissingNormals;
bool hasSmoothGroups;

enum class FaceElement
{
Expand All @@ -38,6 +40,14 @@ class FOBJModel : public FModel
VNormalIndex
};

struct OBJTriRef
{
unsigned int surf;
unsigned int tri;
OBJTriRef(): surf(0), tri(0) {}
OBJTriRef(unsigned int surf, unsigned int tri): surf(surf), tri(tri) {}
bool operator== (OBJTriRef other) { return surf == other.surf && tri == other.tri; }
};
struct OBJFaceSide
{
int vertref;
Expand All @@ -47,7 +57,9 @@ class FOBJModel : public FModel
struct OBJFace
{
unsigned int sideCount;
unsigned int smoothGroup;
OBJFaceSide sides[4];
OBJFace(): sideCount(0), smoothGroup(0) {}
};
struct OBJSurface // 1 surface per 'usemtl'
{
Expand All @@ -66,16 +78,21 @@ class FOBJModel : public FModel
TArray<OBJFace> faces;
TArray<OBJSurface> surfaces;
FScanner sc;
TArray<OBJTriRef>* vertFaces;

int ResolveIndex(int origIndex, FaceElement el);
template<typename T, size_t L> void ParseVector(TArray<T> &array);
bool ParseFaceSide(const FString &side, OBJFace &face, int sidx);
void ConstructSurfaceTris(OBJSurface &surf);
int ResolveIndex(int origIndex, FaceElement el);
void AddVertFaces();
void TriangulateQuad(const OBJFace &quad, OBJFace *tris);
FVector3 RealignVector(FVector3 vecToRealign);
FVector2 FixUV(FVector2 vecToRealign);
FVector3 CalculateNormalFlat(unsigned int surfIdx, unsigned int triIdx);
FVector3 CalculateNormalFlat(OBJTriRef otr);
FVector3 CalculateNormalSmooth(unsigned int vidx, unsigned int smoothGroup);
public:
FOBJModel() {}
FOBJModel(): hasMissingNormals(false), hasSmoothGroups(false), vertFaces(nullptr) {}
~FOBJModel();
bool Load(const char* fn, int lumpnum, const char* buffer, int length) override;
int FindFrame(const char* name) override;
Expand Down

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