opengl学习笔记(二)---中文显示

此方法中用到了glut，freeglut， freetype等库

1.显示英文字符

Opengl 显示英文字符相对做的处理要少一点，可以用glut封装的函数在屏幕上显示英文字符；

	//! Draw a bitmap string;
	static void bitmapString(void* fontId, std::string strText)
	{
		for (unsigned int i = 0; i < (size_t)strText.size(); ++i)
		{
			glutBitmapCharacter(fontId, strText.at(i));
		}

		std::string strLog = "Draw:" + strText;
		cout << strLog << endl;
	}

void display()

		glColor3f(1.0f, 1.0f, 1.0f);
		glRasterPos2f(0, 0);
		glViewport(0,0,glutGet(GLUT_WINDOW_WIDTH), glutGet(GLUT_WINDOW_HEIGHT));
		bitmapString(GLUT_BITMAP_HELVETICA_18, "opengl draw bitmap string test.");

int main()
{

.....

.....

glutDisplayFunc(display);

.....

return 0;

}

2.中文字符

用开源库freetype，有效管理加载*.ttf字体资源

代码:

//Created 2013/04/21;

//! C++;
#include <windows.h>
#include <stdio.h>
#include <stdexcept>
#include <string>
#include <iostream>

//! opengl;
#include <gl\gl.h>
#include <gl\glu.h>
#include <gl\glut.h>

//! freetype;
#include <ft2build.h>
#include FT_FREETYPE_H
#include <freetype/freetype.h>
#include <freetype/ftglyph.h>

using namespace std;

namespace TE
{
	class xFreeTypeLib
	{
	public:
		struct xCharTexture
		{
			GLuint  m_texID;
			wchar_t m_chaID;
			int     m_Width;
			int     m_Height;

			int     m_adv_x;
			int     m_adv_y;
			int     m_delta_x;
			int     m_delta_y;

			xCharTexture()
			{
				m_texID  = 0;
				m_chaID  = 0;
				m_Width  = 0;
				m_Height = 0;
			}
		};
		xCharTexture g_TexID[65536];

		FT_Library m_FT2Lib;
		FT_Face    m_FT_Face;

		int   m_w;
		int   m_h;
	public:
		xFreeTypeLib();
		void load(const char* font_file , int _w , int _h);
		GLuint loadChar(wchar_t ch);

		xCharTexture* getTextChar(wchar_t ch);

	};
	class TEFont
	{
	public:
		TEFont(void);
		~TEFont(void);

		xFreeTypeLib m_FreeTypeLib;

		static TEFont* sharedFont(void);

		void drawText(wchar_t* _strText,int x , int y, int maxW , int h);
	};

}

#include "../TE/TEApplication.h"
#include "../TE/TEGlutWindow.h"
#include "../TE/TEFont.h"

class TEFontTestWin : public TEGlutWindow
{
public:
	TEFontTestWin(){}
	~TEFontTestWin(){}
	virtual void onInit()
	{
		glShadeModel(GL_SMOOTH);							// Enable Smooth Shading
		glClearColor(0.0f, 0.0f, 0.0f, 0.5f);				// Black Background
		glEnable ( GL_COLOR_MATERIAL );
		glColorMaterial ( GL_FRONT, GL_AMBIENT_AND_DIFFUSE );

		TEFont::sharedFont()->m_FreeTypeLib.load("C:\\WINDOWS\\Fonts\\simfang.ttf",20,20);

		glDisable ( GL_CULL_FACE );

	}
	virtual void onRender()
	{
		glClearColor(0.0f , 0.0f , 0.0f , 0.0f);
		glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
		glEnable ( GL_TEXTURE_2D );

		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();
		glColor3f(1,1,1);
		glViewport(0,0,glutGet(GLUT_WINDOW_WIDTH), glutGet(GLUT_WINDOW_HEIGHT));
		glOrtho(0,glutGet(GLUT_WINDOW_WIDTH),glutGet(GLUT_WINDOW_HEIGHT),0,-100,200);
		glMatrixMode(GL_MODELVIEW);
		glLoadIdentity();
		gluLookAt(0, 0, 30 ,0 , 0 ,10 , 0.0f , 1.0f , 0.0f);

		wchar_t strText[] = L"FreeType库是一个完全免费(开源)的、高质量的且可移植的字体引擎，它提供统一的接口来访问多种字体格式文件，包括TrueType, OpenType";
		TEFont::sharedFont()->drawText(strText,50,50,900,25);
		glutSwapBuffers();
	}
};
int main(void)
{
	TEApplication* pApp = new TEApplication();
	TEFontTestWin* pWin = new TEFontTestWin();
	pApp->run();

	delete pWin;
	delete pApp;
	return 0;
}

运行结果：

3.参考链接

1.freetype2 中文显示

2.FreeType Fonts in OpenGL