Opengl ES 1.x NDK实例开发之五:顶点缓存VBO

转自：http://blog.csdn.net/mnorst/article/details/40300191

本章在上一章的基础上讲解顶点缓存数组(Vertex Buffer Object)即VBO的使用，使用VBO来实现金字塔和立方体的绘制，绘制的效果和上一章相同。这个系列教程主要是采用实例演示 Opengl ES 1.x NDK开发，对一些要点进行解释，因此对API的用法和说明较少，建议初学者可以参考Opengl ES 1.x的API手册。

>>>为什么要使用VBO？
   VBO的数据存放在显卡内存中，能节省从系统内存复制到显卡内存中的时间，提高渲染的效率。
>>>VBO顶点缓存的使用范围？
   VBO可以缓存顶点、颜色、纹理坐标、索引。

【实例讲解】

本章示例了VBO缓存顶点、颜色和索引的用法。

【实例源码】

[GLJNIActivity.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 com.android.gljni.GLJNIView;

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

public class GLJNIActivity extends Activity {
    GLJNIView mView;

    @Override
    protected void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        mView = new GLJNIView(getApplication());
        setContentView(mView);
    }

    @Override
    protected void onPause() {
        super.onPause();
        mView.onPause();
    }

    @Override
    protected void onResume() {
        super.onResume();
        mView.onResume();
    }
}

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

import com.android.gljni.GLJNILib;

import android.content.Context;
import android.opengl.GLSurfaceView;

/**
 * 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 {

        public Renderer(Context 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) {
            GLJNILib.init();
        }
    }

}

[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);

    public static native void step();

    public static native void init();
}

[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: 顶点缓冲对象(VBO)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__)

// 定义π
const GLfloat PI = 3.1415f;

// 旋转角度
static GLfloat gAngle = 0.0f;

// 金字塔顶点数组
const GLfloat gVertices[] = {

    // 底面：地面为正方形，拆分为两个三角形
    -1.0f,-1.0f,1.0f,
    1.0f,-1.0f,1.0f,
    1.0f,-1.0f, -1.0f,

    1.0f,-1.0f,-1.0f,
    -1.0f,-1.0f,-1.0f,
    -1.0f,-1.0f,1.0f,

    // 侧面：侧面为4个三角形
    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
};
// 金字塔颜色数组
const GLfloat gColors[] = {
    1.0f,0.0f,0.0f, 1.0f,
    1.0f,0.0f,0.0f, 1.0f,
    1.0f,0.0f,0.0f, 1.0f,

    1.0f,0.0f,0.0f, 1.0f,
    1.0f,0.0f,0.0f, 1.0f,
    1.0f,0.0f,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,

    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,0.0f,1.0f, 1.0f,
    0.0f,1.0f,0.0f, 1.0f,
};


// 立方体顶点数组
#define col 1.0f
#define pos 1.0f

static GLfloat gVerticesSquare[] = {
    -pos,-pos,-pos, /*0*/
    -pos,-pos,pos,  /*1*/
    pos,-pos,pos,   /*2*/
    pos,-pos,-pos,  /*3*/
    -pos,pos,-pos,  /*4*/
    -pos,pos,pos,   /*5*/
    pos,pos,pos,    /*6*/
    pos,pos,-pos,   /*7*/
};
// 立方体顶点索引
static GLubyte gIndexSquare[] = {
    0,2,1,  0,3,2,
    5,1,6,  6,1,2,
    6,2,7,  7,2,3,
    0,4,3,  4,7,3,
    4,0,1,  4,1,5,
    4,5,6,  4,6,7,
};
// 立方体颜色数组
static GLfloat gColorsSquare[] = {
    col,0,0,col,
    0,col,0,col,
    0,0,col,col,
    col,col,0,col,
    col,0,col,col,
    0,col,col,col,
    0,0,0,col,
    col,col,col,col,
};

GLuint gVerticesVBO;
GLuint gColorsVBO;
GLuint gVerticesSquareVBO;
GLuint gColorsSquareVBO;
GLuint gIndexSquareVBO;

/************************************************************************/
/*                             C++代码                                  */
/************************************************************************/

static void printGLString(const char *name, GLenum s) {
    const char *v = (const char *) glGetString(s);
    LOGI("GL %s = %s
", name, v);
}

static void checkGlError(const char* op) {
    for (GLint error = glGetError(); error; error
        = glGetError()) {
            LOGI("after %s() glError (0x%x)
", 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);

    // 启用深度测试
    glEnable(GL_DEPTH_TEST);

    // 所作深度测试的类型
    glDepthFunc(GL_LEQUAL);

    // 对透视进行修正
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

    // VBO相关处理
    // 金字塔
    glGenBuffers(1, &gVerticesVBO);
    glBindBuffer(GL_ARRAY_BUFFER, gVerticesVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(gVertices), gVertices, GL_STATIC_DRAW);
    glGenBuffers(1, &gColorsVBO);
    glBindBuffer(GL_ARRAY_BUFFER, gColorsVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(gColors), gColors, GL_STATIC_DRAW);

    // 立方体
    glGenBuffers(1, &gVerticesSquareVBO);
    glBindBuffer(GL_ARRAY_BUFFER, gVerticesSquareVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(gVerticesSquare), gVerticesSquare, GL_STATIC_DRAW);
    glGenBuffers(1, &gColorsSquareVBO);
    glBindBuffer(GL_ARRAY_BUFFER, gColorsSquareVBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(gColorsSquare), gColorsSquare, GL_STATIC_DRAW);
    glGenBuffers(1, &gIndexSquareVBO);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gIndexSquareVBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(gIndexSquare), gIndexSquare, GL_STATIC_DRAW);

    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);
    // 启用颜色数组
    glEnableClientState(GL_COLOR_ARRAY);

    // 移入屏幕，便于图形显示
    glTranslatef(0.0f,2.0f,-10.0f);

    // 绘制金字塔,采用VBO进行绘制
    glRotatef(gAngle,0.0f,1.0f,0.0f);
    glRotatef(gAngle,1.0f,0.0f,0.0f);
    ////glColorPointer(4, GL_FLOAT, 0, gColors);
    ////glVertexPointer(3, GL_FLOAT, 0, gVertices);
    ////glDrawArrays(GL_TRIANGLES, 0, 20);
    glBindBuffer(GL_ARRAY_BUFFER, gVerticesVBO);
    glVertexPointer(3, GL_FLOAT, 0, 0);
    glBindBuffer(GL_ARRAY_BUFFER, gColorsVBO);
    glColorPointer(4, GL_FLOAT, 0, 0);
    glDrawArrays(GL_TRIANGLES, 0, 20);


    // 绘制立方形,使用ＶＢＯ进行绘制
    // 重置当前的模型观察矩阵
    glLoadIdentity();
    glTranslatef(0.0f, -2.0f,-10.0f);
    glRotatef(gAngle,0.0f,1.0f,0.0f);
    glRotatef(gAngle,1.0f,0.0f,0.0f);

//  glVertexPointer(3,GL_FLOAT,0,gVerticesSquare);
//  glColorPointer(4,GL_FLOAT,0,gColorsSquare);
    glBindBuffer(GL_ARRAY_BUFFER, gVerticesSquareVBO);
    glVertexPointer(3,GL_FLOAT, 0, 0);
    glBindBuffer(GL_ARRAY_BUFFER, gColorsSquareVBO);
    glColorPointer(4, GL_FLOAT, 0, 0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gIndexSquareVBO);
    glDrawElements(GL_TRIANGLES,36,GL_UNSIGNED_BYTE,0);

    // 关闭顶点数组
    glDisableClientState(GL_VERTEX_ARRAY);
    // 关闭颜色数组
    glDisableClientState(GL_COLOR_ARRAY);

    // 增加旋转角度
    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_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();
}