OpenGL ES在Android开发中绘制3D图形的实例详解

// EGLContext的静态方法getEGL获得EGL实例
EGL10 egl = (EGL10)EGLContext.getEGL();
//创建EGLDisplay， EGL_DEFAULT_DISPLAY获得缺省的本地窗口系统类型
EGLDisplay dpy = egl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);
//初始化EGLDispla的同时获得版本号
int[] version = new int[2];
egl.eglInitialize(dpy, version);

EGL10 egl = (EGL10)EGLContext.getEGL();
EGLDisplay dpy = egl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY); int[] version = new int[2];
egl.eglInitialize(dpy, version);
int[] configSpec = {
EGL10.EGL_RED_SIZE, 5,
EGL10.EGL_GREEN_SIZE, 6,
EGL10.EGL_BLUE_SIZE, 5,
EGL10.EGL_DEPTH_SIZE, 16,
EGL10.EGL_NONE
};
EGLConfig[] configs = new EGLConfig[1];
int[] num_config = new int[1];
egl.eglChooseConfig(dpy, configSpec, configs, 1, num_config);
EGLConfig config = configs[0];
EGLContext context = egl.eglCreateContext(dpy, config,
EGL10.EGL_NO_CONTEXT, null);
EGLSurface surface = egl.eglCreateWindowSurface(dpy, config,
sHolder, null);
egl.eglMakeCurrent(dpy, surface, surface, context);
GL10 gl = (GL10)context.getGL();

float vertices[] = {
-1.0f, 1.0f, 0.0f, //左上
-1.0f, -1.0f, 0.0f, //左下
1.0f, -1.0f, 0.0f, //右下
1.0f, 1.0f, 0.0f, //右上
};

ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4);
vbb.order(ByteOrder.nativeOrder());
FloatBuffer vertexBuffer = vbb.asFloatBuffer();
vertexBuffer.put(vertices);
vertexBuffer.position(0);

static private FloatBuffer vertex;//顶点对应的字节缓冲
static private FloatBuffer normal;//法向量对应的字节缓冲
float[] lightPos = new float[] {10.0f, 10.0f, 10.0f, 1.0f };//光源的坐标
private static final int STEP = 24;//
private static final float RADIUS = 1.0f;//半径
protected void init(GL10 gl) {
gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);//设置背景颜色
gl.glLightfv(GL10.GL_LIGHT0, GL10.GL_POSITION, lightPos, 0);
gl.glEnable(GL10.GL_LIGHTING);//启用光照
gl.glEnable(GL10.GL_LIGHT0); //打开光源
gl.glClearDepthf(1.0f);//设置深度缓存
gl.glDepthFunc(GL10.GL_LEQUAL);//设置深度缓存比较函数，GL_LEQUAL表示新的像素的深度缓存值小于等于当前像素的深度缓存值时通过深度测试
gl.glEnable(GL10.GL_DEPTH_TEST);//启用深度缓存
gl.glEnable(GL10.GL_CULL_FACE);
gl.glShadeModel(GL10.GL_SMOOTH);//设置阴影模式GL_SMOOTH
}
protected void drawFrame(GL10 gl) {
gl.glClear(GL10.GL_COLOR_BUFFER_BIT |
GL10.GL_DEPTH_BUFFER_BIT);
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
GLU.gluLookAt(gl, 0, 0, 7f, 0f, 0f, 0f, 0f, 1.0f, 0.0f);//
drawSphere(gl, RADIUS, STEP, STEP); //绘制球形
}
public static void gluLookAt (GL10 gl, float eyeX, float eyeY, float eyeZ, float centerX, float centerY, float centerZ, float upX, float upY, float upZ)

private static void drawSphere(GL10 gl, float radius,
int stacks, int slices) {
vertex=allocateFloatBuffer( 4* 6 * stacks * (slices+1) );
normal=allocateFloatBuffer( 4* 6 * stacks * (slices+1) );
int i, j, triangles;
float slicestep, stackstep;
stackstep = ((float)Math.PI) / stacks;
slicestep = 2.0f * ((float)Math.PI) / slices;
for (i = 0; i < stacks; ++i)
{
float a = i * stackstep;
float b = a + stackstep;
float s0 = (float)Math.sin(a);
float s1 = (float)Math.sin(b);
float c0 = (float)Math.cos(a);
float c1 = (float)Math.cos(b);
float nv;
for (j = 0; j <= slices; ++j)
{
float c = j * slicestep;
float x = (float)Math.cos(c);
float y = (float)Math.sin(c);
nv=x * s0;
normal.put(nv);
vertex.put( nv * radius);
nv=y * s0;
normal.put(nv);
vertex.put( nv * radius);
nv=c0;
normal.put(nv);
vertex.put( nv * radius);
nv=x * s1;
normal.put(nv);
vertex.put( nv * radius);
nv=y * s1;
normal.put(nv);
vertex.put( nv * radius);
nv=c1;
normal.put(nv);
vertex.put( nv * radius);
}
}
normal.position(0);
vertex.position(0);
gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertex);
gl.glNormalPointer(GL10.GL_FLOAT, 0, normal);
gl.glEnableClientState (GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState (GL10.GL_NORMAL_ARRAY);
triangles = (slices + 1) * 2;
for(i = 0; i < stacks; i++)
gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP,
i * triangles, triangles);
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
gl.glDisableClientState(GL10.GL_NORMAL_ARRAY);
}
private static FloatBuffer allocateFloatBuffer(int capacity){
ByteBuffer vbb = ByteBuffer.allocateDirect(capacity);
vbb.order(ByteOrder.nativeOrder());
return vbb.asFloatBuffer();
}