[Android NDK]Android JNI开发例子 ---3 在JNI中实现openGL功能

清疚 2022-09-18 12:54 202阅读 0赞

这个例子使用native部分来实现opengl es而不是java部分。

Java部分与例子2相似。

MainActivity.java

public class MainActivity extends Activity {
    
        GLSurfaceView mGLView;
        static {
            System.loadLibrary("myegl_jni");
        }
        
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            this.requestWindowFeature(Window.FEATURE_NO_TITLE); 
            getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                    WindowManager.LayoutParams.FLAG_FULLSCREEN); // (NEW)
    
            this.mGLView = new MyGLSurfaceView(this);  
            setContentView(this.mGLView);
        }
    }

MyGLSurfaceView.java

public class MyGLSurfaceView extends GLSurfaceView {
    
        GLSurfaceView.Renderer mRenderer;
        private boolean goNative;
    
        /**
         * TODO Put here a description of what this constructor does.
         * 
         * @param context
         * @param goNative
         */
        public MyGLSurfaceView(Context context) {
            super(context);
            // TODO Auto-generated constructor stub.
            mRenderer = new MyRenderer();
            // Set the Renderer for drawing on the GLSurfaceView
            setRenderer(mRenderer);
        }
    }

Renderer.java

public class MyRenderer implements GLSurfaceView.Renderer {
    
        private static final String TAG = "agl";
    
        private native String nativeGetHelloString();
    
        private native void nativeDrawFrame();
    
        private native void nativeSurfaceChanged(int width, int height);
    
        private native void nativeSurfaceCreated();
    
        @Override
        public void onDrawFrame(GL10 gl) {
           nativeDrawFrame();
            Log.d(TAG, "onDrawFrame " + nativeGetHelloString());
        }
    
        @Override
        public void onSurfaceChanged(GL10 gl, int width, int height) {
            nativeSurfaceChanged(width,height);
            Log.d(TAG, "onSurfaceChanged");
        }
    
        @Override
        public void onSurfaceCreated(GL10 gl, EGLConfig config) {
            nativeSurfaceCreated();
            Log.d(TAG, "onSurfaceCreate");
        }
    }

在jni文件夹内创建include文件夹。 在include下创建一个头文件。cpp中的所有变量和函数要在声明之后才能够直接使用。 .h文件中都是声明。

#include <jni.h>
    #include <string.h>
    #include <android/log.h>
    #include <GLES/gl.h>
    #include <GLES/gl.h>
    #include <GLES/glext.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <math.h>
    
    extern "C" {
    #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__)
    #define  LOGD(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
    
    void printGLString(char* name, GLenum s);
    void init();
    void resize(int width, int height);
    void gluPerspective(GLfloat fovy, GLfloat aspect, GLfloat zNear, GLfloat zFar);
    void renderFrame();
    
    GLfloat rtri;  //三角形的旋转变量
    
    GLfloat rquad;  //四边形的旋转变量
    
    const GLfloat PI = 3.1415f;
    
    GLfloat gVertices[] = {
            0.0f, 1.0f, 0.0f,
            -1.0f,-1.0f, 1.0f,
            1.0f,-1.0f, 1.0f,
    
            0.0f, 1.0f, 0.0f,
            1.0f,-1.0f, 1.0f,
            1.0f,-1.0f, -1.0f,
    
            0.0f, 1.0f, 0.0f,
            1.0f,-1.0f, -1.0f,
            -1.0f,-1.0f, -1.0f,
    
            0.0f, 1.0f, 0.0f,
            -1.0f,-1.0f,-1.0f,
            -1.0f,-1.0f, 1.0f
    };
    
    GLfloat gColors[] = {
            1.0f,0.0f,0.0f, 1.0f,
            0.0f,1.0f,0.0f, 1.0f,
            0.0f,0.0f,1.0f, 1.0f,
    
            1.0f,0.0f,0.0f, 1.0f,
            0.0f,0.0f,1.0f, 1.0f,
            0.0f,1.0f,0.0f, 1.0f,
    
            1.0f,0.0f,0.0f, 1.0f,
            0.0f,1.0f,0.0f, 1.0f,
            0.0f,0.0f,1.0f, 1.0f,
    
            1.0f,0.0f,0.0f, 1.0f,
            0.0f,0.0f,1.0f, 1.0f,
            0.0f,1.0f,0.0f, 1.0f
    };
    } //end of extern "C"

cpp文件

#include "com_example_nativeegl_MyRenderer.h"
    
    extern "C" {
    
     void printGLString(char* name, GLenum s) {
    	char *v = (char *) glGetString(s);
    	LOGI("GL %s = %s", name, v);
    }
    
    /*
     * Class:     com_example_nativeegl_MyRenderer
     * Method:    nativeGetHelloString
     * Signature: ()Ljava/lang/String;
     */
    jstring  nativeGetHelloString(JNIEnv *env, jobject obj) {
          return env->NewStringUTF((char*)" This is calling from JNI suckers!");
      }
    
    /*
     * Class:     com_example_nativeegl_MyRenderer
     * Method:    nativeDrawFrame
     * Signature: ()V
     */
    void nativeDrawFrame(JNIEnv *env, jobject obj) {
    	renderFrame();
    }
    
    /*
     * Class:     com_example_nativeegl_MyRenderer
     * Method:    nativeSurfaceChanged
     * Signature: (II)V
     */
    void nativeSurfaceChanged(JNIEnv *env, jobject obj, jint width, jint height){
    	resize(width, height);
    }
    
    void init() {
    	LOGD("init the renderer");
    	glShadeModel(GL_SMOOTH);
    	glClearColor(0.0f,0.0f, 0.0f, 0.0f);
    	glClearDepthf(1.0f);
    	glEnable(GL_DEPTH_TEST);
    	glDepthFunc(GL_LEQUAL);
    	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
    }
    
    void resize(int width, int height) {
    	LOGD("resize the renderer");
    	glViewport(0,0, width, height);
    	glMatrixMode(GL_PROJECTION);
    	glLoadIdentity();
    
    //	GLfloat ratio = (GLfloat)width/(GLfloat)height;
    	gluPerspective(45.0f, (GLfloat)width/(GLfloat)height, 0.1f, 100.0f);
    	//glOrthof(-2.0f, 2.0f, -2.0f, 2.0f, -2.0f, 2.0f);
    
    	glMatrixMode(GL_MODELVIEW);     // 选择模型观察矩阵
    	glLoadIdentity();                         // 重置模型观察矩阵
    }
    
    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 renderFrame() {
    	LOGD("renderFrame the renderer");
    	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // 清除屏幕及深度缓存
    	glLoadIdentity();                   // 重置模型观察矩阵
    	glTranslatef(0.0f,0.0f, -6.0f);             // 移入屏幕 6.0
    
    	glRotatef(rtri,0.0f,1.0f,0.0f);             // 绕Y轴旋转金字塔
    	glEnableClientState(GL_VERTEX_ARRAY);
    	glEnableClientState(GL_COLOR_ARRAY);
    	glColorPointer(4, GL_FLOAT, 0, gColors);
    
    	glVertexPointer(3, GL_FLOAT, 0, gVertices);
    	glDrawArrays(GL_TRIANGLES, 0, 12);
    	rtri += 0.2f;                       // 增加三角形的旋转变量
    	//LOGI("xxxxx");
    	glDisableClientState(GL_VERTEX_ARRAY);
    	glDisableClientState(GL_COLOR_ARRAY);
        glFlush();
    }
    
    /*
     * Class:     com_example_nativeegl_MyRenderer
     * Method:    nativeSurfaceCreated
     * Signature: ()V
     */
     void nativeSurfaceCreated(JNIEnv *env, jobject obj) {
    	 init();
     }
    
    //----------------------------JNI part:Native register------------------------------------------------------
    static JNINativeMethod gMethods[] = {
    		//{"native method name from Java","(arguments type)return type", "(void*)local_native_name"
    		{"nativeGetHelloString", "()Ljava/lang/String;", (void *)nativeGetHelloString},
    		{"nativeDrawFrame", "()V", (void *)nativeDrawFrame},
    		{"nativeSurfaceChanged", "(II)V", (void *)nativeSurfaceChanged},
    		{"nativeSurfaceCreated", "()V", (void *)nativeSurfaceCreated},
    };
    
    static const char* className="com/example/nativeegldynamicjni/MyRenderer";
    
    static int registerNativeMethods(JNIEnv *env) {
    	jclass clazz;
    	clazz = env->FindClass(className);
    	if (clazz == NULL) {
    		LOGD("failed to load the class %s", className);
    		return JNI_FALSE;
    	}
    	if (env->RegisterNatives(clazz, gMethods, sizeof(gMethods)/sizeof(gMethods[0])) < 0) {
    		return JNI_FALSE;
    	}
    	return JNI_TRUE;
    } //end of registerNativeMethods
    
    jint JNI_OnLoad(JavaVM* vm, void* reserved) {
    	JNIEnv* env = NULL;
    	jint result = -1;
    	if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK)
    	{
    		LOGE("ERROR: GetEnv failed\n");
    		goto bail;
    	}
    
    	if (registerNativeMethods(env) < 0) {
    		LOGE("ERROR: jnitest native registration failed\n");
    		goto bail;
    	}
    	result = JNI_VERSION_1_4;
    
    	bail:
    	return result;
    }
    
    } //end of extern "C"

Android.mk

#Description:makefile of Helloworld  
    LOCAL_PATH := $(call my-dir)
    include $(CLEAR_VARS)
    LOCAL_CFLAGS    := -Wall
    LOCAL_MODULE    := myegl_jni
    LOCAL_C_INCLUDES :=$(LOCAL_PATH)/include
    LOCAL_CPP_EXTENSION := .cpp
    LOCAL_LDLIBS += -llog -lGLESv1_CM
    LOCAL_SRC_FILES := com_example_nativeegl_MyRenderer.cpp
    
    include $(BUILD_SHARED_LIBRARY)

在项目根目录想执行ndk-build编译jni出.so库。