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Joel Kiptoo (Kiptoo-Deus) wants to merge 5 commits into
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WaveFrontReader: read per-vertex colors from "v x y z r g b" #329

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74f9362
WaveFrontReader: read per-vertex colors from "v x y z r g b"
Kiptoo-Deus Oct 5, 2026
7cb75cb
WaveFrontReader: apply clang-format
Kiptoo-Deus Oct 9, 2026
b421c2f
Merge remote-tracking branch 'origin/main' into wavefront-vertex-colors
Kiptoo-Deus Oct 9, 2026
a095220
meshconvert: load OBJ per-vertex colors
Kiptoo-Deus Oct 14, 2026
585b1e9
meshconvert: note that the OBJ layouts match WaveFrontReader::Vertex
Kiptoo-Deus Oct 14, 2026
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41 changes: 40 additions & 1 deletion Meshconvert/MeshOBJ.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,7 @@ HRESULT LoadFromOBJ(const wchar_t* szFilename, std::unique_ptr<Mesh>& inMesh, st
if (FAILED(hr))
return hr;

// These layouts are only used to extract data, so the offsets match WaveFrontReader::Vertex
static const D3D11_INPUT_ELEMENT_DESC s_vboLayout[] = {
{ "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
{ "NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 12, D3D11_INPUT_PER_VERTEX_DATA, 0 },
Expand All @@ -91,10 +92,33 @@ HRESULT LoadFromOBJ(const wchar_t* szFilename, std::unique_ptr<Mesh>& inMesh, st
{ "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 24, D3D11_INPUT_PER_VERTEX_DATA, 0 },
};

// Vertex colors are read from a second stream (slot 1) alongside the Vertex data
static const D3D11_INPUT_ELEMENT_DESC s_vboLayoutVC[] = {
{ "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
{ "NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 12, D3D11_INPUT_PER_VERTEX_DATA, 0 },
{ "COLOR", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 1, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
{ "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 24, D3D11_INPUT_PER_VERTEX_DATA, 0 },
};

static const D3D11_INPUT_ELEMENT_DESC s_vboLayoutAltVC[] = {
{ "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
{ "COLOR", 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 1, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
{ "TEXCOORD", 0, DXGI_FORMAT_R32G32_FLOAT, 0, 24, D3D11_INPUT_PER_VERTEX_DATA, 0 },
};

const D3D11_INPUT_ELEMENT_DESC* layout = s_vboLayout;
size_t nDecl = std::size(s_vboLayout);

if (!wfReader.hasNormals && !wfReader.hasTexcoords)
const bool hasColors = wfReader.hasVertexColors && (wfReader.vertexColors.size() == wfReader.vertices.size());

if (hasColors)
{
layout = (wfReader.hasNormals) ? s_vboLayoutVC : s_vboLayoutAltVC;
nDecl = (wfReader.hasNormals) ? std::size(s_vboLayoutVC) : std::size(s_vboLayoutAltVC);
if (!wfReader.hasTexcoords)
--nDecl;
}
else if (!wfReader.hasNormals && !wfReader.hasTexcoords)
{
nDecl = 1;
}
Expand All @@ -117,6 +141,21 @@ HRESULT LoadFromOBJ(const wchar_t* szFilename, std::unique_ptr<Mesh>& inMesh, st
if (FAILED(hr))
return hr;

std::vector<XMFLOAT4> colors;
if (hasColors)
{
// OBJ vertex colors have no alpha, so use opaque
colors.reserve(wfReader.vertexColors.size());
for (const auto& c : wfReader.vertexColors)
{
colors.emplace_back(c.x, c.y, c.z, 1.f);
}

hr = vbr.AddStream(colors.data(), colors.size(), 1, sizeof(XMFLOAT4));
if (FAILED(hr))
return hr;
}

hr = inMesh->SetVertexData(vbr, wfReader.vertices.size());
if (FAILED(hr))
return hr;
Expand Down
53 changes: 50 additions & 3 deletions Utilities/WaveFrontReader.h
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,7 @@
#include <cwctype>
#include <fstream>
#include <locale>
#include <sstream>
#include <string>
#include <vector>
#include <unordered_map>
Expand All @@ -75,7 +76,8 @@ namespace DX

WaveFrontReader() noexcept
: hasNormals(false),
hasTexcoords(false)
hasTexcoords(false),
hasVertexColors(false)
{}

HRESULT Load(_In_z_ const wchar_t* szFileName, bool ccw = true, bool loadmtl = true)
Expand Down Expand Up @@ -107,6 +109,7 @@ namespace DX
std::vector<XMFLOAT3> positions;
std::vector<XMFLOAT3> normals;
std::vector<XMFLOAT2> texCoords;
std::vector<XMFLOAT3> positionColors;

VertexCache vertexCache;

Expand Down Expand Up @@ -152,6 +155,32 @@ namespace DX
float x, y, z;
InFile >> x >> y >> z;
positions.emplace_back(XMFLOAT3(x, y, z));

// Some tools (e.g. MeshLab) write a per-vertex color after the position as
// "v x y z r g b". This is not part of the OBJ specification, so only exactly
// three extra values are treated as a color; a single extra value is the
// optional 'w' coordinate and is ignored.
XMFLOAT3 color(1.f, 1.f, 1.f);

std::wstring rest;
std::getline(InFile, rest, L'\n');
InFile.putback(L'\n');

std::wistringstream extra(rest);
extra.imbue(std::locale::classic());

float values[4] = {};
size_t count = 0;
while (count < std::size(values) && extra >> values[count])
++count;

if (count == 3)
{
color = XMFLOAT3(values[0], values[1], values[2]);
hasVertexColors = true;
}

positionColors.emplace_back(color);
}
else if (0 == wcscmp(strCommand.c_str(), L"vt"))
{
Expand Down Expand Up @@ -284,6 +313,12 @@ namespace DX
if (index == uint32_t(-1))
return E_OUTOFMEMORY;

if (index == vertexColors.size())
{
// New vertex: its color comes from the position it was built from
vertexColors.emplace_back(positionColors[vertexIndex]);
}

constexpr uint32_t maxIndex = (sizeof(index_t) == 2) ? UINT16_MAX : UINT32_MAX;
if (index >= maxIndex)
{
Expand Down Expand Up @@ -399,6 +434,11 @@ namespace DX
if (positions.empty())
return E_FAIL;

if (!hasVertexColors)
{
vertexColors.clear();
}

// Cleanup
InFile.close();

Expand Down Expand Up @@ -617,9 +657,11 @@ namespace DX
indices.clear();
attributes.clear();
materials.clear();
vertexColors.clear();
name.clear();
hasNormals = false;
hasTexcoords = false;
hasNormals = false;
hasTexcoords = false;
hasVertexColors = false;

bounds.Center.x = bounds.Center.y = bounds.Center.z = 0.f;
bounds.Extents.x = bounds.Extents.y = bounds.Extents.z = 0.f;
Expand Down Expand Up @@ -739,9 +781,14 @@ namespace DX
std::vector<uint32_t> attributes;
std::vector<Material> materials;

// Per-vertex colors from the non-standard "v x y z r g b" extension, one per entry in
// 'vertices'. Only filled in when hasVertexColors is true.
std::vector<DirectX::XMFLOAT3> vertexColors;

std::wstring name;
bool hasNormals;
bool hasTexcoords;
bool hasVertexColors;

DirectX::BoundingBox bounds;

Expand Down