ktxparse

A simple KTX texture parser for OpenGL, implemented in C++

• Only depends on the standard library
• Does not allocate or modify memory
• Does not throw exceptions
• Validates image formats and sizes
• Single lightweight header
• Hassle-free Boost Software License

Limitations

• Key-value metadata is ignored
• No support for legacy OESCPT palette formats
• No support for exotic core formats GL_RGBA2, GL_RGB4, GL_RGB5, GL_RGB10, GL_RGB12, GL_RGBA12

Example

GLuint loadKTX(constuint8_t* data, size_t size)
{
ktxparse::Texture ktx{data, size};
if (!ktx)
return0;
GLuint name{0};
glGenTextures(1, &name);
glBindTexture(ktx.target, name);
glTexParameteri(ktx.target, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(ktx.target, GL_TEXTURE_MAX_LEVEL, ktx.levels - 1);
switch (ktx.dimensions)
{
case1:
glTexStorage1D(
ktx.target, ktx.levels, ktx.internalformat, ktx.width);
for (auto img : ktx)
if (ktx.isCompressed)
glCompressedTexSubImage1D(
img.target, img.level, 0, img.width,
img.format, img.size, img.data);
elseglTexSubImage1D(
img.target, img.level, 0, img.width,
img.format, img.type, img.data);
break;
case2:
glTexStorage2D(
ktx.target, ktx.levels, ktx.internalformat,
ktx.width, ktx.height);
for (auto img : ktx)
if (ktx.isCompressed)
glCompressedTexSubImage2D(
img.target, img.level, 0, 0, img.width,
img.height, img.format, img.size, img.data);
elseglTexSubImage2D(
img.target, img.level, 0, 0, img.width,
img.height, img.format, img.type, img.data);
break;
case3:
glTexStorage3D(
ktx.target, ktx.levels, ktx.internalformat,
ktx.width, ktx.height, ktx.depth);
for (auto img : ktx)
if (ktx.isCompressed)
glCompressedTexSubImage3D(
img.target, img.level, 0, 0, 0, img.width,
img.height, img.depth, img.format, img.size, img.data);
elseglTexSubImage3D(
img.target, img.level, 0, 0, 0, img.width,
img.height, img.depth, img.format, img.type, img.data);
break;
}
return name;
}

Interface

The Texture constructor initializes arguments for functions like glTexImage, glTexStorage, and glTexSubImage. The arguments have the same name and type as documented by OpenGL.

The constructor may fail if the input is incorrect. In that case, the object is left in an undefined state. Before using a Texture object, make sure that it returns true when converted to bool.

structTexture
{
uint32_t target;
uint32_t dimensions; // For gl*D()uint32_t levels; // Ignores shouldGenerateMipmapuint32_t internalformat;
uint32_t width;
uint32_t height;
uint32_t depth;
bool isByteSwapped; // For GL_UNPACK_SWAP_BYTESbool isCompressed; // For glCompressed*()bool shouldGenerateMipmap; // For glGenerateMipmap()// Parses data from memory.// Can handle nullptr.Texture(constuint8_t* data, size_t size) // Checks if the construction was successful.// Alterations to public members are ignored.explicitoperatorbool() const
ImageIterator begin() const
ImageIterator end() const
};

A Texture provides standard begin and end functions, to iterate through the images in a ranged-based for loop. The iterator constructs Image objects and returns them by value.

structImage
{
uint32_t target;
int32_t level;
int32_t internalformat;
uint32_t width;
uint32_t height;
uint32_t depth;
uint32_t format;
uint32_t type;
uint32_t size;
constuint8_t* data;
};

Install

This is a header-only library. Simply add the header from the include directory to your project.

The unit tests can be compiled and run with:

mkdir build
cd build
cmake ..
make
./test/ktxparse-test