How to write a Ptex quad face

How to write a Ptex quad

Basically a hello world for using the Ptex API for writing quad face.
The second example writes random colors to triangle meshes.

Makefile

TARGET = ptex
test: $(TARGET)
	./$(TARGET)
	ptxinfo -d test.ptx
$(TARGET): $(TARGET).cc
	g++ -Wall -o $(TARGET) $(TARGET).cc -lPtex
c: clean
clean:
	rm -f $(TARGET) test.ptx
e: edit
edit:
	vi $(TARGET).cc

ptex.cc

// Write one Ptex quad face (ptex.us)

#include <iostream>
#include <cmath>
#include "Ptexture.h"

using namespace std;

int main()
{
	string filename = "test.ptx";
	auto meshType = Ptex::mt_quad;
	auto dataType = Ptex::dt_uint8;
	auto channels = 3;
	auto alpha = -1;
	auto numberFaces = 1;
	Ptex::String error;

	PtexPtr<PtexWriter> writer(PtexWriter::open(filename.c_str(),
						    meshType,
						    dataType,
						    channels,
						    alpha,
						    numberFaces,
						    error));

	int height = 2;
	int width = 2;
	const int noFace = -1;
	const int noEdge = 0;
	int adjFaces[4] = {noFace, noFace, noFace, noFace};
	int adjEdges[4] = {noEdge, noEdge, noEdge, noEdge};

	Ptex::Res resolution(log2(width), log2(height));
	Ptex::FaceInfo faceInfo(resolution, adjFaces, adjEdges);

	struct Color {
		uint8_t r;
		uint8_t g;
		uint8_t b;
	};

	Color texels[height * width];
	const int white = 255;
	const int gray = 128;

	for (int j = 0; j < height * width; j++)
	{
		texels[j].r = j;
		texels[j].g = gray;
		texels[j].b = white;
	}

	auto faceId = 0;

	writer->writeFace(faceId, faceInfo, texels);
}

random_triangle_color.cc

// Write a ptex file with random colors for a triangle mesh.
//
// You only have to specify the number of triangles that you can find out
// easily for obj files with "grep '^f' bla.obj|wc -l".
// No adjency information is given.

#include <iostream>
#include <cmath>
#include <random>
#include <vector>
#include "Ptexture.h"

using namespace std;

//auto numberFaces = 69666; // bunny
auto numberFaces = 15744; // suzanne

struct Color {
	uint8_t r;
	uint8_t g;
	uint8_t b;
};
Color red {255, 0, 0};
Color white {255, 255, 255};
Color black {0, 0, 0};

Color randomColor() {
	random_device device;
	mt19937 engine(device());
	uniform_int_distribution<uint8_t> distribution(0, 255);
	auto r = distribution(engine);
	auto g = distribution(engine);
	auto b = distribution(engine);
	return Color{r, g, b};
}

vector<Color> texelsFromColor(int count, Color color) {
	vector<Color> texels(count);
	for (int i = 0; i < count; i++)
		texels[i] = color;
	return texels;
}

int main()
{
	string filename = "test.ptx";
	auto meshType = Ptex::mt_triangle;
	auto dataType = Ptex::dt_uint8;
	auto channels = 3;
	auto alpha = -1;
	Ptex::String error;

	PtexPtr<PtexWriter> writer(PtexWriter::open(filename.c_str(),
						    meshType,
						    dataType,
						    channels,
						    alpha,
						    numberFaces,
						    error));

	int height = 2;
	int width = 2;
	const int noFace = -1;
	const int noEdge = 0;
	int adjFaces[4] = {noFace, noFace, noFace, noFace};
	int adjEdges[4] = {noEdge, noEdge, noEdge, noEdge};

	Ptex::Res resolution(log2(width), log2(height));
	Ptex::FaceInfo faceInfo(resolution, adjFaces, adjEdges);

	int numberTexels = width * height;

	for (auto faceId = 0; faceId < numberFaces; faceId++) {
		auto texels = texelsFromColor(numberTexels, randomColor());
		writer->writeFace(faceId, faceInfo, texels.data());
	}
}