Windows下使用GetGlyphOutline在OpenGL中渲染字体

标签：c++   opengl   三维   字体   

        欢迎转载，请标明出处：http://blog.csdn.net/tianyu2202/

        无图无JB，先上图。使用OpenGL绘制字体，支持多种字体，支持TrueType轮廓字体，支持自选字体纹理大小和输出大小，支持在三维空间内绘制。

        关于OpenGL中字体的显示网上其实有很多的教程，不过经常用到的方式有比较简单的Bitmap方式、比较复杂的FreeType方式。而本文介绍的方式虽然只能在Windows下实现，却有着和FreeType一样的显示效果，最重要的是非常简单，仅仅200多行代码即可实现。

        首先是字体信息的保存，每个文字都有数个信息需要保存，包括了纹理的宽高、起始位置、字体宽度和所在的纹理序号。本文将每个字体保存为一个纹理，而不是常见的一个纹理保存数十个文字。这是首先是为了简单，二来还有应用上的一些特殊性。有这方面要求的同学可以自行优化。

class CFontData
{
public:
	float m_Width, m_Height;
	float m_OrigX, m_OrigY;
	float m_FontWidth;
	GLuint m_TextureID;

	CFontData()
	{
		m_Width = 0.0f;
		m_Height = 0.0f;
		m_TextureID = 0;
		m_FontWidth = 0.0f;
		m_OrigX = 0.0f;
		m_OrigY = 0.0f;
	}

	~CFontData()
	{

	}
};

class CFontPrinter
{
private:
	int m_FontSize;
	wchar_t m_FontName[64];
	std::map<wchar_t, CFontData*> m_FontMap;
	HFONT m_Font;

public:
	CFontPrinter(int fontSize, const wchar_t* fontName)
	{
		wcscpy_s(m_FontName, 64, fontName);
		m_FontSize = fontSize;
		m_Font = NULL;
	}

	~CFontPrinter()
	{

	}

	bool makeChar(wchar_t wChar);

	void print3DText(float x, float y, float z, float red, float green, float blue, float height, wchar_t* Text);

	void print3DText(float x, float y, float z, float height, wchar_t* Text)
	{
		return print3DText(x, y, z, 1.0f, 1.0f, 1.0f, height, Text);
	}
};

        然后计算所需的数据，存入FontMap中等待绘制。

bool CFontPrinter::makeChar(wchar_t wChar)
{
	HDC hdc = CreateCompatibleDC(wglGetCurrentDC());

	if(!hdc)
		return false;

	HBITMAP hbitmap = CreateCompatibleBitmap(hdc, 1, 1);
	HBITMAP hbitmapOld = (HBITMAP)SelectObject(hdc, hbitmap);

	if((DWORD)hbitmapOld == GDI_ERROR)
		return false;

	CFontData* fontData = new CFontData();

	glGenTextures(1, &fontData->m_TextureID);
	glBindTexture(GL_TEXTURE_2D, fontData->m_TextureID);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

	glPixelStorei(GL_UNPACK_SWAP_BYTES, GL_FALSE);
	glPixelStorei(GL_UNPACK_LSB_FIRST, GL_FALSE);
	glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
	glPixelStorei(GL_UNPACK_SKIP_ROWS, 0);
	glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

	int iTexWidth = m_FontSize;
	int iTexHeight = m_FontSize;
	int iLevel = 0;

	if (!m_Font)
	{
		// 创建文字
		m_Font = CreateFontW(-m_FontSize, 0, 0, 0, 500, false, false, false,
			DEFAULT_CHARSET, OUT_TT_ONLY_PRECIS, CLIP_DEFAULT_PRECIS,
			DEFAULT_QUALITY, DEFAULT_PITCH | (m_FontName?FF_DONTCARE:FF_SWISS),	m_FontName);
	}
	if(!m_Font)
		return false;

	HFONT hfontOld = (HFONT)SelectObject(hdc, m_Font);
	if((DWORD)hfontOld == GDI_ERROR)
		return false;

	GLYPHMETRICS gm={0,};
	MAT2 const matrix22_identity={{0,1},{0,0},{0,0},{0,1}};

	DWORD dwBuffSize = GetGlyphOutlineW(hdc, wChar, GGO_GRAY8_BITMAP, &gm, 0, NULL, &matrix22_identity);

	if((signed)dwBuffSize == -1)
	{
		return false;
	}

	if(GetGlyphOutlineW(hdc, wChar, GGO_METRICS, &gm, 0, NULL, &matrix22_identity)==GDI_ERROR)
	{
		return false;
	}

	BYTE *pBuff = new BYTE[dwBuffSize];
	BYTE *pSwapBuff=new BYTE[dwBuffSize];
	memset(pBuff, 0xff, dwBuffSize);
	memset(pSwapBuff, 0xff, dwBuffSize);

	if(GetGlyphOutlineW(hdc, wChar, GGO_GRAY8_BITMAP, &gm, dwBuffSize, pBuff, &matrix22_identity) == GDI_ERROR)
	{
		delete[] pBuff;
		return false;
	}

	if(gm.gmBlackBoxY == 0)
	{
		printf("black box Y zero!!!\n");
		return false;
	}

	// 从 Gray64 转换到 Gray256
	unsigned int const uiRowSize = dwBuffSize / gm.gmBlackBoxY;
	BYTE* pPtr;
	BYTE* pSPtr;
	for(unsigned int nY = 0; nY < gm.gmBlackBoxY; nY++)
	{
		pPtr = pBuff + uiRowSize * nY;
		pSPtr = pSwapBuff + gm.gmBlackBoxX * nY;
		for (unsigned int nX = 0; nX < gm.gmBlackBoxX; nX++)
		{
			if (*pPtr == 0)
			{
				*pSPtr = 0;
			}
			else if (*pPtr == 0x40)
			{
				*pSPtr = 0xff;
			}
			else
			{
				*pSPtr = *pPtr << 2;
			}

			pPtr++;
			pSPtr++;
		}
	}

	// 加载纹理
	glTexImage2D(GL_TEXTURE_2D, iLevel, GL_LUMINANCE8, gm.gmBlackBoxX, gm.gmBlackBoxY, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, pSwapBuff);

	// 记录文字信息
	fontData->m_FontWidth = (float)gm.gmCellIncX / (float)m_FontSize;
	fontData->m_Width = (float)gm.gmBlackBoxX / (float)m_FontSize;
	fontData->m_Height = (float)gm.gmBlackBoxY / (float)m_FontSize;
	fontData->m_OrigX = (float)gm.gmptGlyphOrigin.x / (float)m_FontSize;
	fontData->m_OrigY = 1.0f - (float)gm.gmptGlyphOrigin.y / (float)m_FontSize;

	m_FontMap[wChar] = fontData;

	delete[] pBuff;
	delete[] pSwapBuff;

	return true;
}

void Render()
{
	static float FrameID = 0;

	if (FrameID > 2 * PI)
	{
		FrameID = 0.0f;
	}
	else
	{
		FrameID += PI / 180.0f;
	}

	glDrawBuffer(GL_BACK);
	glViewport(0, 0, m_Width, m_Height);
	glClearColor(0.3f, 0.4f, 0.5f, 1.0f);
	glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();

	for (int i = 0; i < 20; i++)
	{
		fontPrinter->print3DText(sin(FrameID - PI180 * i) * 0.3f - 0.7f, cos(FrameID - PI180 * i), 0.0f, 1.0f, 1.0f, 1.0f, 0.3f, L"中文输出");
		fontPrinter->print3DText(cos(FrameID - PI180 * i) * 0.4f - 0.8f, sin(FrameID - PI180 * i) * 0.4f, 0.0f, 0.0f, 1.0f, 0.0f, 0.2f, L"Hello Class");
		fontPrinterSong->print3DText(cos(FrameID - PI180 * i) * 0.5f - 0.9f, sin(FrameID - PI180 * i) * 0.6f, 0.0f, 0.0f, 0.0f, 1.0f, 0.4f, L"Font Class");
	}
	fontPrinter->print3DText(-0.7f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.2f, L"Font World");
	fontPrinterSong->print3DText(-0.7f, -0.6f, 0.0f, 1.0f, 0.0f, 0.0f, 0.2f, L"宋体字");
	fontPrinter->print3DText(-0.7f, -0.2f, 0.0f, 1.0f, 0.0f, 0.0f, 0.2f, L"微软雅黑");

	glFlush();

	SwapBuffers(m_hDC);
}

// 初始化文字
void InitFont()
{	
	// 参数1 单个文字纹理的最大大小
	// 参数2 字体的文件名称
	fontPrinter = new CFontPrinter(96, L"微软雅黑");
	fontPrinterSong = new CFontPrinter(96, L"宋体");
}

int __stdcall WinMain( __in HINSTANCE hInstance, __in_opt HINSTANCE hPrevInstance, __in_opt LPSTR lpCmdLine, __in int nShowCmd )
{
	MSG  msg;

	CreateClientWindow();
	InitFont();

	while (true)
	{
		if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))          // 有消息在等待吗?
		{
			if (msg.message == WM_QUIT)      // 收到退出消息?
			{
				// 退出程序
				break;
			}
			else
			{
				TranslateMessage(&msg);                                  // 翻译消息
				DispatchMessage(&msg);                                   // 发送消息
			}
		}
		else
		{
			Render();
		}
	}

	if (fontPrinter != NULL)
	{
		delete fontPrinter;
	}

	return 0;
}

Windows下使用GetGlyphOutline在OpenGL中渲染字体,布布扣,bubuko.com

Windows下使用GetGlyphOutline在OpenGL中渲染字体

标签：c++   opengl   三维   字体   

原文地址：http://blog.csdn.net/tianyu2202/article/details/38732603