开发框架介绍请參见：Opengl ES NDK实例开发之中的一个:搭建开发框架

本章在第三章(Opengl ES 1.x NDK实例开发之三:多边形的旋转)的基础上演示怎样使用纹理贴图，分别实现了三角形纹理贴图和正方形纹理贴图。

【实例解说】

OpenglES要求生成纹理的图片长宽为2的n次方。支持各种格式(BMP, GIF, JPEG, PNG...)

本例中使用的图片为png格式，尺寸为128*128

本例中，在上层GLJNIView.java中生成纹理。将纹理句柄传递给Native层进行绘制。详见

private void genTexture(GL10 gl, Context context)

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【实例源代码】

[GLJNIActivity.java]

[GLJNIView.java]

/*

 * Copyright (C) 2007 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 *

 * author: mnorst@foxmail.com

 */

package com.android.gljni;

import java.io.IOException;

import java.io.InputStream;

import javax.microedition.khronos.egl.EGLConfig;

import javax.microedition.khronos.opengles.GL10;

import com.android.gljni.GLJNILib;

import com.android.gljnidemo06.R;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.opengl.GLSurfaceView;

import android.opengl.GLUtils;

import android.util.Log;

/**

 * A simple GLSurfaceView sub-class that demonstrate how to perform

 * OpenGL ES 1.x rendering into a GL Surface.

 */

public class GLJNIView extends GLSurfaceView {

	private static final String LOG_TAG = GLJNIView.class.getSimpleName();

	private Renderer renderer;

	public GLJNIView(Context context) {

		super(context);

		// setEGLConfigChooser会对fps产生影响

		setEGLConfigChooser(8, 8, 8, 8, 16, 0);

		renderer = new Renderer(context);

		setRenderer(renderer);

	}

	private static class Renderer implements GLSurfaceView.Renderer {

		//用于纹理映射的绑定，并把绑定后的ID传递给C++代码。供其调用

		private int[] mTexture = new int[2];

		//用于载入Bitmap的context

		private Context mContext;

		public Renderer(Context ctx) {

			mContext = ctx;

		}

		public void onDrawFrame(GL10 gl) {

			GLJNILib.step();

		}

		public void onSurfaceChanged(GL10 gl, int width, int height) {

			GLJNILib.resize(width, height);

		}

		public void onSurfaceCreated(GL10 gl, EGLConfig config) {

			//用来绑定Bitmap纹理

			genTexture(gl, mContext);

			//调用本地setTexture方法，把纹理绑定的ID传递给C++代码，以供其调用

			GLJNILib.setTexture(mTexture);

			GLJNILib.init();

		}

		/**

		 * 载入Bitmap的方法，

		 * 用来从res中载入Bitmap资源

		 * */

		private Bitmap loadBitmap(Context context, int resourceId) {

			InputStream is = context.getResources().openRawResource(resourceId);

			Bitmap bitmap = null;

			try {

				// 利用BitmapFactory生成Bitmap

				bitmap = BitmapFactory.decodeStream(is);

			} finally {

				try {

					// 关闭流

					is.close();

					is = null;

				} catch (IOException e) {

					e.printStackTrace();

				}

			}

			return bitmap;

		}

		/**

		 * 绑定Bitmap纹理

		 * */

		private void genTexture(GL10 gl, Context context) {

			//生成纹理

			gl.glGenTextures(2, mTexture, 0);

			//载入Bitmap

			Bitmap bitmap = loadBitmap(context, R.drawable.logo);

			if (bitmap != null) {

				//假设bitmap载入成功。则生成此bitmap的纹理映射

				gl.glBindTexture(GL10.GL_TEXTURE_2D, mTexture[0]);

				//设置纹理映射的属性

				gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,

						GL10.GL_NEAREST);

				gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER,

						GL10.GL_NEAREST);

				//生成纹理映射

				GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);

				//释放bitmap资源

				bitmap.recycle();

			}

		}

	}

}

[GLJNILib.java]

/*

 * Copyright (C) 2007 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 *

 * author: mnorst@foxmail.com

 */

package com.android.gljni;

//Wrapper for native library

public class GLJNILib {

	static {

		System.loadLibrary("gljni");

	}

	/**

     * @param width the current view width

     * @param height the current view height

     */

	public static native void resize(int width, int height); 

	/**

	 * render

	 */

    public static native void step();  

    /**

     * init

     */

    public static native void init();  

    /**

     * set the texture

     * @param texture	texture id

     */

    public static native void setTexture(int[] texture);

}

[[gl_code.cpp]

/*

 * Copyright (C) 2007 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 *

 * author: 	mnorst@foxmail.com

 * created:	2014/10/20

 * purpose:	纹理的使用

 */

// OpenGL ES 1.x code

#include <jni.h>

#include <android/log.h>

#include <GLES/gl.h>

#include <GLES/glext.h>

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

/************************************************************************/

/*                             定义                                     */

/************************************************************************/

#define  LOG_TAG    "libgljni"

#define  LOGI(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)

#define  LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)

//初始化纹理数组

GLuint *gTexture = 0;

// 定义π

const GLfloat PI = 3.1415f;

// 旋转角度

static GLfloat gAngle = 0.0f; 

// 顶点数组

const GLfloat gVertices[] = {

	0.0f, 1.0f, 0.0f,	// 上

	-1.0f,-1.0f, 0.0f,	// 左下

	1.0f,-1.0f, 0.0f,	// 右下

};

const GLfloat gVerticesSquare[] = {

	-1.0f, -1.0f, 0.0f, // 左下

	1.0f, -1.0f, 0.0f, 	// 右下

	-1.0f, 1.0f, 0.0f, 	// 左上

	1.0f, 1.0f, 0.0f 	// 右上

};

// 纹理坐标

// 纹理坐标原点会因不同系统环境而有所不同。

// 比方在iOS以及Android上，纹理坐标原点（0, 0）是在左上角

// 而在OS X上，纹理坐标的原点是在左下角

const GLfloat gTextureCoord[] = {

	0.5f,0.0f,

	0.0f,1.0f,

	1.0f,1.0f,

};

const GLfloat gTextureSquareCoord[] = {

	0.0f,1.0f,

	1.0f,1.0f,

	0.0f,0.0f,

	1.0f,0.0f,

};

/************************************************************************/

/*                             C++代码                                  */

/************************************************************************/

static void printGLString(const char *name, GLenum s) {

	const char *v = (const char *) glGetString(s);

	LOGI("GL %s = %s\n", name, v);

}

static void checkGlError(const char* op) {

	for (GLint error = glGetError(); error; error

		= glGetError()) {

			LOGI("after %s() glError (0x%x)\n", op, error);

	}

}

bool init() {

	printGLString("Version", GL_VERSION);

	printGLString("Vendor", GL_VENDOR);

	printGLString("Renderer", GL_RENDERER);

	printGLString("Extensions", GL_EXTENSIONS);

	// 启用阴影平滑

	glShadeModel(GL_SMOOTH);

	// 黑色背景

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);	

	// 设置深度缓存

	glClearDepthf(1.0f);

	// 启用深度測试

	glEnable(GL_DEPTH_TEST);	

	// 所作深度測试的类型

	glDepthFunc(GL_LEQUAL);	

	// 对透视进行修正

	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	

	return true;

}

static void _gluPerspective(GLfloat fovy, GLfloat aspect, GLfloat zNear, GLfloat zFar)

{

	GLfloat top = zNear * ((GLfloat) tan(fovy * PI / 360.0));

	GLfloat bottom = -top;

	GLfloat left = bottom * aspect;

	GLfloat right = top * aspect;

	glFrustumf(left, right, bottom, top, zNear, zFar);

}

void resize(int width, int height)

{

	// 防止被零除

	if (height==0)

	{

		height=1;

	}

	// 重置当前的视口

	glViewport(0, 0, width, height);

	// 选择投影矩阵

	glMatrixMode(GL_PROJECTION);

	// 重置投影矩阵

	glLoadIdentity();							

	// 设置视口的大小

	_gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

	// 选择模型观察矩阵

	glMatrixMode(GL_MODELVIEW);	

	// 重置模型观察矩阵

	glLoadIdentity();

}

void renderFrame() {

	// 清除屏幕及深度缓存

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	// 设置背景颜色为黑色

	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

	// 重置当前的模型观察矩阵

	glLoadIdentity();		

	// 启用顶点数组

	glEnableClientState(GL_VERTEX_ARRAY);

	glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

	// 纹理设置

	glEnable(GL_TEXTURE_2D);								// 启用纹理映射

	glBindTexture(GL_TEXTURE_2D, gTexture[0]);				// 选择纹理

	glEnableClientState(GL_TEXTURE_COORD_ARRAY);			// 启用纹理坐标数组

	// 绘制三角形

	glTranslatef(0.0f,2.0f,-10.0f);							// 设置三角形位置

	glRotatef(gAngle,0.0f,1.0f,0.0f);						// 旋转三角形

	glVertexPointer(3, GL_FLOAT, 0, gVertices);				// 指定顶点数组

	glTexCoordPointer(2, GL_FLOAT, 0, gTextureCoord);		// 设置纹理坐标

	glDrawArrays(GL_TRIANGLES, 0, 3);						// 绘制三角形

	// 绘制正方形

	glTranslatef(0.0f,-4.0f,0.0f);							// 设置正方形位置

	glRotatef(-gAngle*2,0.0f,1.0f,0.0f);					// 旋转正方形

	glVertexPointer(3, GL_FLOAT, 0, gVerticesSquare);		// 指定顶点数组

	glTexCoordPointer(2, GL_FLOAT, 0, gTextureSquareCoord);	// 设置纹理坐标

	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);					// 绘制正方形

	// 关闭顶点数组

	glDisableClientState(GL_VERTEX_ARRAY);

	// 关闭纹理数组

	glDisableClientState(GL_TEXTURE_COORD_ARRAY);

	glDisable(GL_TEXTURE_2D);

	// 添加旋转角度

	gAngle += 2.0f;

}

/************************************************************************/

/*                          JNI代码                                     */

/************************************************************************/

extern "C" {

	JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_resize(JNIEnv * env, jobject obj,  jint width, jint height);

	JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_step(JNIEnv * env, jobject obj);

	JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_init(JNIEnv * env, jobject obj);

	JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_setTexture(JNIEnv * env, jclass obj, jintArray tex);

};

JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_resize(JNIEnv * env, jobject obj,  jint width, jint height)

{

	resize(width, height);

}

JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_step(JNIEnv * env, jobject obj)

{

	renderFrame();

}

JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_init(JNIEnv * env, jobject obj)

{

	init();

}

JNIEXPORT void JNICALL Java_com_android_gljni_GLJNILib_setTexture(JNIEnv * env, jclass obj, jintArray tex)

{

	gTexture = (GLuint *)env->GetIntArrayElements(tex,0);

}