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Opengl ES 1.x NDK实例开发之四:立方体的旋转

2014-10-13 16:01 381 查看

开发框架介绍请参见：Opengl ES NDK实例开发之一:搭建开发框架

【实例讲解】

本章在第三章的基础上讲解如何绘制立方体并按照各自的中心进行旋转

绘制立方体实际上是绘制立方体的各个面，其中金字塔包括三个三角形侧面和一个正方形底面，

因为opengl ES里面不支持直接绘制正方形，所以需要将正方形拆分为两个三角形，

因此金字塔总共需要绘制5个三角形

立方体总共有8个顶点，我们在这里采用顶点索引的方式进行绘制

索引里面的值表示顶点的序号

两个立方体按照各自的中心进行旋转，关键代码如下

// 重置当前的模型观察矩阵
glLoadIdentity();

【实例源码】

[GLJNIActivity.java]

[java] view
plaincopy

/*

* 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]

[java] view
plaincopy

/*
* 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:	2014/10/13
* purpose:	旋转的立方体
*/

// 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,
};

/************************************************************************/
/*                             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);

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
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);

// 绘制立方形
// 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);
glDrawElements(GL_TRIANGLES,36,GL_UNSIGNED_BYTE,gIndexSquare);

// 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();
}

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