利用JNI技术在Android中调用C++形式的OpenGL ES 2.0函数

1、                 打开Eclipse，File-->New-->Project…-->Android-->AndroidApplication Project,Next-->Application Name:FillTriangle, PackageName:com.filltriangle.android,Minimum Required SDK:API 10Android2.3.3(Gingerbread),Next-->不勾选Create customlauncher icon，Next-->选中Blank Activity,Next-->Activity Name:FillTriangle,Finish-->Runas Android Application，查看是否一切运行正常；

2、                 打开FillTriangleActivity.java，将其内容改为：

package com.filltriangle.android;import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.WindowManager;import java.io.File;public class FillTriangleActivity extends Activity {GL2JNIView mView;@Override protected void onCreate(Bundle icicle) {super.onCreate(icicle);mView = new GL2JNIView(getApplication());setContentView(mView);}@Override protected void onPause() {super.onPause();mView.onPause();}@Override protected void onResume() {super.onResume();mView.onResume();}}

3、 新建2个java文件，选中com.filltriangle.android,点击右键，New-->Class,Name:GL2JNILib和Name:GL2JNIView；

4、GL2JNILib.java文件内容为：

package com.filltriangle.android;//Wrapper for native librarypublic class GL2JNILib {static {System.loadLibrary("gl2jni");}/*** @param width the current view width* @param height the current view height*/public static native void init(int width, int height);public static native void step();
}

5、 GL2JNIView.java文件内容为：

package com.filltriangle.android;import android.content.Context;
import android.graphics.PixelFormat;
import android.opengl.GLSurfaceView;
import android.util.AttributeSet;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.egl.EGLContext;
import javax.microedition.khronos.egl.EGLDisplay;
import javax.microedition.khronos.opengles.GL10;/*** A simple GLSurfaceView sub-class that demonstrate how to perform* OpenGL ES 2.0 rendering into a GL Surface. Note the following important* details:** - The class must use a custom context factory to enable 2.0 rendering.*   See ContextFactory class definition below.** - The class must use a custom EGLConfigChooser to be able to select*   an EGLConfig that supports 2.0. This is done by providing a config*   specification to eglChooseConfig() that has the attribute*   EGL10.ELG_RENDERABLE_TYPE containing the EGL_OPENGL_ES2_BIT flag*   set. See ConfigChooser class definition below.** - The class must select the surface's format, then choose an EGLConfig*   that matches it exactly (with regards to red/green/blue/alpha channels*   bit depths). Failure to do so would result in an EGL_BAD_MATCH error.*/class GL2JNIView extends GLSurfaceView {private static String TAG = "GL2JNIView";private static final boolean DEBUG = false;public GL2JNIView(Context context) {super(context);init(false, 0, 0);}public GL2JNIView(Context context, boolean translucent, int depth, int stencil) {super(context);init(translucent, depth, stencil);}private void init(boolean translucent, int depth, int stencil) {/* By default, GLSurfaceView() creates a RGB_565 opaque surface.* If we want a translucent one, we should change the surface's* format here, using PixelFormat.TRANSLUCENT for GL Surfaces* is interpreted as any 32-bit surface with alpha by SurfaceFlinger.*/if (translucent) {this.getHolder().setFormat(PixelFormat.TRANSLUCENT);}/* Setup the context factory for 2.0 rendering.* See ContextFactory class definition below*/setEGLContextFactory(new ContextFactory());/* We need to choose an EGLConfig that matches the format of* our surface exactly. This is going to be done in our* custom config chooser. See ConfigChooser class definition* below.*/  setEGLConfigChooser( translucent ?new ConfigChooser(8, 8, 8, 8, depth, stencil) :new ConfigChooser(5, 6, 5, 0, depth, stencil) );/* Set the renderer responsible for frame rendering */setRenderer(new Renderer());}private static class ContextFactory implements GLSurfaceView.EGLContextFactory {private static int EGL_CONTEXT_CLIENT_VERSION = 0x3098;public EGLContext createContext(EGL10 egl, EGLDisplay display, EGLConfig eglConfig) {Log.w(TAG, "creating OpenGL ES 2.0 context");checkEglError("Before eglCreateContext", egl);int[] attrib_list = {EGL_CONTEXT_CLIENT_VERSION, 2, EGL10.EGL_NONE };EGLContext context = egl.eglCreateContext(display, eglConfig, EGL10.EGL_NO_CONTEXT, attrib_list);checkEglError("After eglCreateContext", egl);return context;}public void destroyContext(EGL10 egl, EGLDisplay display, EGLContext context) {egl.eglDestroyContext(display, context);}}private static void checkEglError(String prompt, EGL10 egl) {int error;while ((error = egl.eglGetError()) != EGL10.EGL_SUCCESS) {Log.e(TAG, String.format("%s: EGL error: 0x%x", prompt, error));}}private static class ConfigChooser implements GLSurfaceView.EGLConfigChooser {public ConfigChooser(int r, int g, int b, int a, int depth, int stencil) {mRedSize = r;mGreenSize = g;mBlueSize = b;mAlphaSize = a;mDepthSize = depth;mStencilSize = stencil;}/* This EGL config specification is used to specify 2.0 rendering.* We use a minimum size of 4 bits for red/green/blue, but will* perform actual matching in chooseConfig() below.*/private static int EGL_OPENGL_ES2_BIT = 4;private static int[] s_configAttribs2 ={EGL10.EGL_RED_SIZE, 4,EGL10.EGL_GREEN_SIZE, 4,EGL10.EGL_BLUE_SIZE, 4,EGL10.EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,EGL10.EGL_NONE};public EGLConfig chooseConfig(EGL10 egl, EGLDisplay display) {/* Get the number of minimally matching EGL configurations*/int[] num_config = new int[1];egl.eglChooseConfig(display, s_configAttribs2, null, 0, num_config);int numConfigs = num_config[0];if (numConfigs <= 0) {throw new IllegalArgumentException("No configs match configSpec");}/* Allocate then read the array of minimally matching EGL configs*/EGLConfig[] configs = new EGLConfig[numConfigs];egl.eglChooseConfig(display, s_configAttribs2, configs, numConfigs, num_config);if (DEBUG) {printConfigs(egl, display, configs);}/* Now return the "best" one*/return chooseConfig(egl, display, configs);}public EGLConfig chooseConfig(EGL10 egl, EGLDisplay display,EGLConfig[] configs) {for(EGLConfig config : configs) {int d = findConfigAttrib(egl, display, config,EGL10.EGL_DEPTH_SIZE, 0);int s = findConfigAttrib(egl, display, config,EGL10.EGL_STENCIL_SIZE, 0);// We need at least mDepthSize and mStencilSize bitsif (d < mDepthSize || s < mStencilSize)continue;// We want an *exact* match for red/green/blue/alphaint r = findConfigAttrib(egl, display, config,EGL10.EGL_RED_SIZE, 0);int g = findConfigAttrib(egl, display, config,EGL10.EGL_GREEN_SIZE, 0);int b = findConfigAttrib(egl, display, config,EGL10.EGL_BLUE_SIZE, 0);int a = findConfigAttrib(egl, display, config,EGL10.EGL_ALPHA_SIZE, 0);if (r == mRedSize && g == mGreenSize && b == mBlueSize && a == mAlphaSize)return config;}return null;}private int findConfigAttrib(EGL10 egl, EGLDisplay display,EGLConfig config, int attribute, int defaultValue) {if (egl.eglGetConfigAttrib(display, config, attribute, mValue)) {return mValue[0];}return defaultValue;}private void printConfigs(EGL10 egl, EGLDisplay display,EGLConfig[] configs) {int numConfigs = configs.length;Log.w(TAG, String.format("%d configurations", numConfigs));for (int i = 0; i < numConfigs; i++) {Log.w(TAG, String.format("Configuration %d:\n", i));printConfig(egl, display, configs[i]);}}private void printConfig(EGL10 egl, EGLDisplay display,EGLConfig config) {int[] attributes = {EGL10.EGL_BUFFER_SIZE,EGL10.EGL_ALPHA_SIZE,EGL10.EGL_BLUE_SIZE,EGL10.EGL_GREEN_SIZE,EGL10.EGL_RED_SIZE,EGL10.EGL_DEPTH_SIZE,EGL10.EGL_STENCIL_SIZE,EGL10.EGL_CONFIG_CAVEAT,EGL10.EGL_CONFIG_ID,EGL10.EGL_LEVEL,EGL10.EGL_MAX_PBUFFER_HEIGHT,EGL10.EGL_MAX_PBUFFER_PIXELS,EGL10.EGL_MAX_PBUFFER_WIDTH,EGL10.EGL_NATIVE_RENDERABLE,EGL10.EGL_NATIVE_VISUAL_ID,EGL10.EGL_NATIVE_VISUAL_TYPE,0x3030, // EGL10.EGL_PRESERVED_RESOURCES,EGL10.EGL_SAMPLES,EGL10.EGL_SAMPLE_BUFFERS,EGL10.EGL_SURFACE_TYPE,EGL10.EGL_TRANSPARENT_TYPE,EGL10.EGL_TRANSPARENT_RED_VALUE,EGL10.EGL_TRANSPARENT_GREEN_VALUE,EGL10.EGL_TRANSPARENT_BLUE_VALUE,0x3039, // EGL10.EGL_BIND_TO_TEXTURE_RGB,0x303A, // EGL10.EGL_BIND_TO_TEXTURE_RGBA,0x303B, // EGL10.EGL_MIN_SWAP_INTERVAL,0x303C, // EGL10.EGL_MAX_SWAP_INTERVAL,EGL10.EGL_LUMINANCE_SIZE,EGL10.EGL_ALPHA_MASK_SIZE,EGL10.EGL_COLOR_BUFFER_TYPE,EGL10.EGL_RENDERABLE_TYPE,0x3042 // EGL10.EGL_CONFORMANT};String[] names = {"EGL_BUFFER_SIZE","EGL_ALPHA_SIZE","EGL_BLUE_SIZE","EGL_GREEN_SIZE","EGL_RED_SIZE","EGL_DEPTH_SIZE","EGL_STENCIL_SIZE","EGL_CONFIG_CAVEAT","EGL_CONFIG_ID","EGL_LEVEL","EGL_MAX_PBUFFER_HEIGHT","EGL_MAX_PBUFFER_PIXELS","EGL_MAX_PBUFFER_WIDTH","EGL_NATIVE_RENDERABLE","EGL_NATIVE_VISUAL_ID","EGL_NATIVE_VISUAL_TYPE","EGL_PRESERVED_RESOURCES","EGL_SAMPLES","EGL_SAMPLE_BUFFERS","EGL_SURFACE_TYPE","EGL_TRANSPARENT_TYPE","EGL_TRANSPARENT_RED_VALUE","EGL_TRANSPARENT_GREEN_VALUE","EGL_TRANSPARENT_BLUE_VALUE","EGL_BIND_TO_TEXTURE_RGB","EGL_BIND_TO_TEXTURE_RGBA","EGL_MIN_SWAP_INTERVAL","EGL_MAX_SWAP_INTERVAL","EGL_LUMINANCE_SIZE","EGL_ALPHA_MASK_SIZE","EGL_COLOR_BUFFER_TYPE","EGL_RENDERABLE_TYPE","EGL_CONFORMANT"};int[] value = new int[1];for (int i = 0; i < attributes.length; i++) {int attribute = attributes[i];String name = names[i];if ( egl.eglGetConfigAttrib(display, config, attribute, value)) {Log.w(TAG, String.format("  %s: %d\n", name, value[0]));} else {// Log.w(TAG, String.format("  %s: failed\n", name));while (egl.eglGetError() != EGL10.EGL_SUCCESS);}}}// Subclasses can adjust these values:protected int mRedSize;protected int mGreenSize;protected int mBlueSize;protected int mAlphaSize;protected int mDepthSize;protected int mStencilSize;private int[] mValue = new int[1];}private static class Renderer implements GLSurfaceView.Renderer {public void onDrawFrame(GL10 gl) {GL2JNILib.step();}public void onSurfaceChanged(GL10 gl, int width, int height) {GL2JNILib.init(width, height);}public void onSurfaceCreated(GL10 gl, EGLConfig config) {// Do nothing.}}
}

6、编译该工程，会在bin\classes\com\filltriangle\android文件夹下生成GL2JNILib.class等文件；

7、打开命令行窗口，将其定位到\bin\classes目录下，输入命令：javah –classpath   D:\ProgramFiles\Android\android-sdk\platforms\android-10\android.jar;(不用忘掉此分号) com.filltriangle.android.GL2JNILib，会在classes文件夹下生成com_filltriangle_android_GL2JNILib.h(说明：*.jar也可以是其它版本)；

8、生成的com_filltriangle_android_GL2JNILib.h文件内容为：

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_filltriangle_android_GL2JNILib */#ifndef _Included_com_filltriangle_android_GL2JNILib
#define _Included_com_filltriangle_android_GL2JNILib
#ifdef __cplusplus
extern "C" {
#endif
/** Class:     com_filltriangle_android_GL2JNILib* Method:    init* Signature: (II)V*/
JNIEXPORT void JNICALL Java_com_filltriangle_android_GL2JNILib_init(JNIEnv *, jclass, jint, jint);/** Class:     com_filltriangle_android_GL2JNILib* Method:    step* Signature: ()V*/
JNIEXPORT void JNICALL Java_com_filltriangle_android_GL2JNILib_step(JNIEnv *, jclass);#ifdef __cplusplus
}
#endif
#endif

9、选中FillTriangle工程，点击右键-->New-->Folder新建一个jni文件夹，选中jni, -->New-->File,新建2个文件，名称分别为Android.mk和opengles_code.cpp；

10、Android.mk文件内容为：

LOCAL_PATH:= $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE    := libgl2jni
LOCAL_CFLAGS    := -Werror
LOCAL_SRC_FILES := opengles_code.cpp
LOCAL_LDLIBS    := -llog -lGLESv2include $(BUILD_SHARED_LIBRARY)

11、opengles_code.cpp文件内容为：

/** Copyright (C) 2009 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.*/// OpenGL ES 2.0 code#include <jni.h>
#include <android/log.h>#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>#include <stdio.h>
#include <stdlib.h>
#include <math.h>#define  LOG_TAG    "libgl2jni"
#define  LOGI(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define  LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)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);}
}static const char gVertexShader[] = "attribute vec4 vPosition;\n""void main() {\n""  gl_Position = vPosition;\n""}\n";static const char gFragmentShader[] = "precision mediump float;\n""void main() {\n""  gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);\n""}\n";GLuint loadShader(GLenum shaderType, const char* pSource) {GLuint shader = glCreateShader(shaderType);if (shader) {glShaderSource(shader, 1, &pSource, NULL);glCompileShader(shader);GLint compiled = 0;glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);if (!compiled) {GLint infoLen = 0;glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);if (infoLen) {char* buf = (char*) malloc(infoLen);if (buf) {glGetShaderInfoLog(shader, infoLen, NULL, buf);LOGE("Could not compile shader %d:\n%s\n",shaderType, buf);free(buf);}glDeleteShader(shader);shader = 0;}}}return shader;
}GLuint createProgram(const char* pVertexSource, const char* pFragmentSource) {GLuint vertexShader = loadShader(GL_VERTEX_SHADER, pVertexSource);if (!vertexShader) {return 0;}GLuint pixelShader = loadShader(GL_FRAGMENT_SHADER, pFragmentSource);if (!pixelShader) {return 0;}GLuint program = glCreateProgram();if (program) {glAttachShader(program, vertexShader);checkGlError("glAttachShader");glAttachShader(program, pixelShader);checkGlError("glAttachShader");glLinkProgram(program);GLint linkStatus = GL_FALSE;glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);if (linkStatus != GL_TRUE) {GLint bufLength = 0;glGetProgramiv(program, GL_INFO_LOG_LENGTH, &bufLength);if (bufLength) {char* buf = (char*) malloc(bufLength);if (buf) {glGetProgramInfoLog(program, bufLength, NULL, buf);LOGE("Could not link program:\n%s\n", buf);free(buf);}}glDeleteProgram(program);program = 0;}}return program;
}GLuint gProgram;
GLuint gvPositionHandle;bool setupGraphics(int w, int h) {printGLString("Version", GL_VERSION);printGLString("Vendor", GL_VENDOR);printGLString("Renderer", GL_RENDERER);printGLString("Extensions", GL_EXTENSIONS);LOGI("setupGraphics(%d, %d)", w, h);gProgram = createProgram(gVertexShader, gFragmentShader);if (!gProgram) {LOGE("Could not create program.");return false;}gvPositionHandle = glGetAttribLocation(gProgram, "vPosition");checkGlError("glGetAttribLocation");LOGI("glGetAttribLocation(\"vPosition\") = %d\n",gvPositionHandle);glViewport(0, 0, w, h);checkGlError("glViewport");return true;
}const GLfloat gTriangleVertices[] = { 0.0f, 0.5f, -0.5f, -0.5f,0.5f, -0.5f };void renderFrame() {static float grey;grey += 0.01f;if (grey > 1.0f) {grey = 0.0f;}glClearColor(grey, grey, grey, 1.0f);checkGlError("glClearColor");glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);checkGlError("glClear");glUseProgram(gProgram);checkGlError("glUseProgram");glVertexAttribPointer(gvPositionHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices);checkGlError("glVertexAttribPointer");glEnableVertexAttribArray(gvPositionHandle);checkGlError("glEnableVertexAttribArray");glDrawArrays(GL_TRIANGLES, 0, 3);checkGlError("glDrawArrays");
}extern "C" {JNIEXPORT void JNICALL Java_com_filltriangle_android_GL2JNILib_init(JNIEnv * env, jobject obj,  jint width, jint height);JNIEXPORT void JNICALL Java_com_filltriangle_android_GL2JNILib_step(JNIEnv * env, jobject obj);
};JNIEXPORT void JNICALL Java_com_filltriangle_android_GL2JNILib_init(JNIEnv * env, jobject obj,  jint width, jint height)
{setupGraphics(width, height);
}JNIEXPORT void JNICALL Java_com_filltriangle_android_GL2JNILib_step(JNIEnv * env, jobject obj)
{renderFrame();
}

12、利用NDK生成.so文件：选中工程，点击右键-->Properties-->Builders-->New,新建立一个Builder,在弹出的对话框上点中Program,点击OK；在弹出对话框EditConfiguration中，配置选项卡Main：Location中填入NDK安装目录，D:\ProgramFiles\Android\android-sdk\android-ndk-r9\ndk-build.cmd；WorkingDirectory中填入工程的根目录，E:\Test\Android\FillTriangle,点击Apply；配置选项卡Refresh,勾选Refreshresources upon completion, The entire workspace, Recursively includesub-folders,点击Apply;配置Build Options选项卡，勾选Allocate Console(necessary for input), After a “Clean”, Duringmanual builds, During auto builds, Specify working set of relevant resources,点击SpecifyResources..,勾选FillTriangle工程的jni目录，点击Finish,点击Apply，点击OK,会在\libs\armeabi目录下生成相应的libgl2jni.so库；

13、运行该工程，会显示绿色三角。

参考文献：

1、  以上代码来自adt-bundle-windows-x86_64-20130729中的例程；

2、 http://blog.csdn.net/fengbingchun/article/details/11580983