C++ opengl 纹理生成

程序运行截图如下：

看着很炫酷：其实是图片炫酷

程序源码如下：

void Init() {
	glMatrixMode(GL_PROJECTION);
	gluPerspective(50.0f, 800.0f / 600.0f, 0.1f, 1000.0f);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	int nFileSize = 0;
	unsigned char *bmpFileContent = LoadFileContent("Res/test.bmp", nFileSize);
	int bmpWidth = 0, bmpHeight = 0;
	unsigned char*pixelData = DecodeBMP(bmpFileContent, bmpWidth, bmpHeight);

	//最后一个参数传GL_RGB因为BMP图无α通道
	texture = CreateTexture2D(pixelData, bmpWidth, bmpHeight, GL_RGB);	//创建OpenGL纹理对象
}

void Draw() {
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT);
	glEnable(GL_TEXTURE_2D);	//开启2D纹理
	glBindTexture(GL_TEXTURE_2D, texture);//将当前纹理设置为新创建的纹理对象
	glBegin(GL_QUADS);
	glColor4ub(255, 255, 255, 255);
	glTexCoord2f(0.0f, 0.0f);
	glVertex3f(-0.1f, -0.1f, -0.4f);
	glTexCoord2f(1.0f, 0.0f);
	glVertex3f(0.1f, -0.1f, -0.4f);
	glTexCoord2f(1.0f, 1.0f);
	glVertex3f(0.1f, 0.1f, -0.4f);
	glTexCoord2f(0.0f, 1.0f);
	glVertex3f(-0.1f, 0.1f, -0.4f);
	glEnd();
}

其中LoadFileContext函数如下：

unsigned char * LoadFileContent(const char *path, int &filesize) {
	unsigned char*fileContent = nullptr;
	filesize = 0;
	FILE*pFile = fopen(path, "rb");
	if (pFile) {
		fseek(pFile, 0, SEEK_END);
		int nLen = ftell(pFile);
		if (nLen > 0) {
			rewind(pFile);
			fileContent = new unsigned char[nLen + 1];
			fread(fileContent, sizeof(unsigned char), nLen, pFile);
			fileContent[nLen] = '\0';
			filesize = nLen;
		}
		fclose(pFile);
	}
	return fileContent;
}

DecodeBMP函数如下：

unsigned char* DecodeBMP(unsigned char*bmpFileData, int&width, int&height) {
	if (0x4D42 == *((unsigned short*)bmpFileData)) {
		int pixelDataOffset = *((int*)(bmpFileData + 10));
		width = *((int*)(bmpFileData + 18));
		height = *((int*)(bmpFileData + 22));
		unsigned char*pixelData = bmpFileData + pixelDataOffset;
		for (int i = 0; i < width*height * 3; i += 3) {
			unsigned char temp = pixelData[i];
			pixelData[i] = pixelData[i + 2];
			pixelData[i + 2] = temp;
		}
		return pixelData;
	}
	return nullptr;
}

createTexture2D函数如下：

GLuint CreateTexture2D(unsigned char*pixelData, int width, int height, GLenum type) {
	GLuint texture;
	glGenTextures(1, &texture);
	glBindTexture(GL_TEXTURE_2D, texture);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
	glTexImage2D(GL_TEXTURE_2D, 0, type, width, height, 0, type, GL_UNSIGNED_BYTE, pixelData);
	glBindTexture(GL_TEXTURE_2D, 0);
	return texture;
}