android opengl es 绘制位图字体

Android中绘制字体，用到了canvas，下面代码里面为我写的实例，几乎每行代码都有注释。

1.Activity 类

import android.app.Activity;
import android.opengl.GLSurfaceView;
import android.os.Bundle;

public class FontOpenglActivity extends Activity {
   GLSurfaceView gView ;
   FontRenderer fontRenderer;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        gView = new GLSurfaceView(this);
        fontRenderer = new FontRenderer();
        gView.setRenderer(fontRenderer);
        setContentView(gView);
    }
}

2.渲染类

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL;
import javax.microedition.khronos.opengles.GL10;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.opengl.GLUtils;
import android.opengl.GLSurfaceView.Renderer;

public class FontRenderer implements Renderer {
	//位图
	private Bitmap bitmap;
	//四边形的顶点坐标系
	private float[] vertex = new float[]{
			-2.5f,-2.5f,0,
			2.5f,-2.5f,0,
			-2.5f,2.5f,0,
			2.5f,2.5f,0
	};
	//纹理坐标系
	private float[] coord = new float[]{
			0,1.0f,
			1.0f,1.0f,
			0,0,
			1.0f,0
	};
	//纹理存储定义，一般用来存名称
	private int[] textures = new int[1];
	//顶点、纹理缓冲
	FloatBuffer vertexBuffer;
	FloatBuffer coordBuffer;
	
	@Override
	public void onDrawFrame(GL10 gl) {
		gl.glClear(GL10.GL_DEPTH_BUFFER_BIT|GL10.GL_COLOR_BUFFER_BIT);
		gl.glLoadIdentity();
		
		//准备顶点缓冲
		ByteBuffer bb = ByteBuffer.allocateDirect(vertex.length * 4);
		bb.order(ByteOrder.nativeOrder());
		vertexBuffer = bb.asFloatBuffer();
		vertexBuffer.put(vertex);
		vertexBuffer.position(0);
		//准备纹理缓冲
		ByteBuffer coordbb = ByteBuffer.allocateDirect(coord.length * 4);
		coordbb.order(ByteOrder.nativeOrder());
		coordBuffer = coordbb.asFloatBuffer();
		coordBuffer.put(coord);
		coordBuffer.position(0);
		//开启顶点和纹理缓冲
		gl.glEnableClientState(gl.GL_VERTEX_ARRAY);
		gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
		
		//往里面进去一点
		gl.glTranslatef(0.0f, 0.0f, -6.0f);
		//设置顶点和纹理的位置、类型
		gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
		gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, coordBuffer);
		//绘图
		gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
		//取消缓冲
		gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
		gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
		//结束绘图
		gl.glFinish();
	}

	@Override
	public void onSurfaceChanged(GL10 gl, int width, int height) {
		//设置场景大小
		gl.glViewport(0, 0, width, height);
		float ratio = (float) width / height;
		//投影矩阵
		gl.glMatrixMode(GL10.GL_PROJECTION);
		//重置视图
		gl.glLoadIdentity();
		//设置视图的大小
		gl.glFrustumf(-ratio, ratio, -1, 1, 1, 15);
		// 设置观察模型
		gl.glMatrixMode(GL10.GL_MODELVIEW);
		gl.glLoadIdentity();
	}

	@Override
	public void onSurfaceCreated(GL10 gl, EGLConfig config) {
		initFontBitmap();
		
		gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
		// 黑色背景色
		gl.glClearColorx(0, 0, 0, 0);
		// 启用阴影平滑
		gl.glShadeModel(GL10.GL_SMOOTH);
		// 启用深度测试
		gl.glEnable(GL10.GL_DEPTH_TEST);
		// 深度测试类型
		gl.glDepthFunc(GL10.GL_LEQUAL);
		// 设置深度缓存
		gl.glClearDepthf(1.0f);

		// 启用纹理
		gl.glEnable(GL10.GL_TEXTURE_2D);
		// 创建纹理
		 gl.glGenTextures(1, textures, 0);
		// 绑定纹理
		 gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
		 //生成纹理
		GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);

		//线性滤波
		gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER,
				GL10.GL_LINEAR);//放大时
		gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,
				GL10.GL_LINEAR);//缩小时	
	}
	/**
	 * android中绘制字体，使用画布canvas
	 */
	public void initFontBitmap(){
		String font = "需要渲染的文字测试！";
		bitmap = Bitmap.createBitmap(256, 256, Bitmap.Config.ARGB_8888);
		Canvas canvas = new Canvas(bitmap);
		//背景颜色
		canvas.drawColor(Color.LTGRAY);
		Paint p = new Paint();
		//字体设置
		String fontType = "宋体";
		Typeface typeface = Typeface.create(fontType, Typeface.BOLD);
		//消除锯齿
		p.setAntiAlias(true);
		//字体为红色
		p.setColor(Color.RED);
		p.setTypeface(typeface);
		p.setTextSize(28);
		//绘制字体
		canvas.drawText(font, 0, 100, p);
	}
}

3、运行效果