GLTexture.cpp

#include "GLTexture.h"
#include <cstdint>
#include <utility>

#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>

cGLTexture::cGLTexture(const std::string& textureName)
	: mTextureName(textureName), mTextureId(0) 
{
}

cGLTexture::cGLTexture(const std::string& textureName, GLint textureId)
	: mTextureName(textureName), mTextureId(textureId) 
{
}

cGLTexture::cGLTexture(cGLTexture&& other) noexcept
	: mTextureName(std::move(other.mTextureName)),
	mTextureId(other.mTextureId) 
{
	other.mTextureId = 0;
}

cGLTexture& cGLTexture::operator=(cGLTexture&& other) noexcept
{
	mTextureName = std::move(other.mTextureName);
	std::swap(mTextureId, other.mTextureId);
	return *this;
}

cGLTexture::~cGLTexture() noexcept {
	if (mTextureId)
		glDeleteTextures(1, &mTextureId);
}

GLuint cGLTexture::texture() const 
{ 
	return mTextureId; 
}

const std::string& cGLTexture::textureName() const 
{ 
	return mTextureName; 
}

cGLTexture::handleType cGLTexture::load(const std::string& fileName) 
{
	if (mTextureId) {
		glDeleteTextures(1, &mTextureId);
		mTextureId = 0;
	}
	int force_channels = 0;
	int w, h, n;
	handleType textureData(stbi_load(fileName.c_str(), &w, &h, &n, force_channels), stbi_image_free);
	if (!textureData)
		throw std::invalid_argument("Could not load texture data from file " + fileName);
	glGenTextures(1, &mTextureId);
	glBindTexture(GL_TEXTURE_2D, mTextureId);
	GLint internalFormat;
	GLint format;
	switch (n) {
	case 1: internalFormat = GL_R8; format = GL_RED; break;
	case 2: internalFormat = GL_RG8; format = GL_RG; break;
	case 3: internalFormat = GL_RGB8; format = GL_RGB; break;
	case 4: internalFormat = GL_RGBA8; format = GL_RGBA; break;
	default: internalFormat = 0; format = 0; break;
	}
	glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, w, h, 0, format, GL_UNSIGNED_BYTE, textureData.get());
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	return textureData;
}