OpenGL ES 绘制立方体

立方体.png

public class EGLView extends GLSurfaceView {
public EGLView(Context context) {
super(context);
init();
}

private void init() {
    setEGLContextClientVersion(2);
    Renderer renderer = new Renderer();
    setRenderer(renderer);
    setRenderMode(RENDERMODE_CONTINUOUSLY);
}

public class Renderer implements GLSurfaceView.Renderer {
Cube cube;
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
//设置背景颜色
GLES20.glClearColor(0.5f,0.5f,0.5f,0.5f);
//开启深度测试
GLES20.glEnable(GLES20.GL_DEPTH_TEST);
cube=new Cube();
}

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
        //设置视口
        GLES20.glViewport(0,0,width,height);
        //计算宽高比
        float r=(float) width/height;
        //计算透视投影
        Matrix.frustumM(Cube.mProjMatrix,0,-r,r,-1,1,3,20);
        //设置相机位置
        Matrix.setLookAtM(Cube.mVMatrix,0,
                5f,5f,10, //相机位置
                0f,0f,0f, //目标位置
                1f,1f,0f);//up位置

    }

    @Override
    public void onDrawFrame(GL10 gl) {
        //清除颜色很深度缓存
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT|GLES20.GL_DEPTH_BUFFER_BIT);
        //绘制
        cube.drawSelf();
    }
}

}

public class Cube extends Utils {
private FloatBuffer verBuffer;
private FloatBuffer colorBuffer;
private ShortBuffer intdexBuffer;
private int mProgram;
private int vPosition, aColor;
private int vMatrix;

public Cube() {
    initData();
    initShader();
}

private void initData() {
    //顶点
    verBuffer = getFloatBuffer(cubePositions);
    //颜色
    colorBuffer = getFloatBuffer(color);
    //所有
    intdexBuffer = getShortBuffer(intdex);
}

private void initShader() {

    //创建程序
    mProgram = GLES20.glCreateProgram();
    //管理着色器源码
    GLES20.glAttachShader(mProgram, loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode));
    GLES20.glAttachShader(mProgram, loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode));
    //连接程序
    GLES20.glLinkProgram(mProgram);
    //获取GLSL的变量id
    vPosition = GLES20.glGetAttribLocation(mProgram, "vPosition");
    aColor = GLES20.glGetAttribLocation(mProgram, "aColor");
    vMatrix = GLES20.glGetUniformLocation(mProgram, "vMatrix");

}

// 设置矩阵变换的所用到的矩阵
public static float[] mProjMatrix = new float[16];//4x4矩阵 投影用
public static float[] mVMatrix = new float[16];//摄像机位置朝向9参数矩阵
public static float[] mMVPMatrix;//最后起作用的总变换矩阵
public static float[] mMMatrix = new float[16];//具体物体的移动旋转矩阵，旋转、平移
public float xAngle = 0;//绕x轴旋转的角度

//绘制
public void drawSelf() {
    //加载到OpenGL ES环境中
    GLES20.glUseProgram(mProgram);
    //变换矩阵
    Matrix.setRotateM(mMMatrix, 0, 0, 0, 1, 0);
    //位移 z轴正向位移
    Matrix.translateM(mMMatrix, 0, 0, 0, 1);
    //旋转Z轴正向位移
    Matrix.rotateM(mMMatrix, 0, xAngle, 1, 1, 1);
    //给glsl变量赋值
    GLES20.glUniformMatrix4fv(vMatrix, 1, false, getMatrix(mMMatrix), 0);
    //设置数据
    GLES20.glVertexAttribPointer(vPosition, 3, GLES20.GL_FLOAT, false, 0, verBuffer);
    GLES20.glVertexAttribPointer(aColor, 4, GLES20.GL_FLOAT, false, 0, colorBuffer);
    //开启顶点和颜色
    GLES20.glEnableVertexAttribArray(vPosition);
    GLES20.glEnableVertexAttribArray(aColor);
    //绘制
    GLES20.glDrawElements(GLES20.GL_TRIANGLES, 36, GLES20.GL_UNSIGNED_SHORT, intdexBuffer);

}

//矩阵相乘操作
public float[] getMatrix(float[] spec) {
    mMVPMatrix = new float[16];
    //位移操作
    Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, spec, 0);
    //合并投影和视口矩阵
    Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0);
    return mMVPMatrix;
}

;

}

public abstract class Utils {
/**
* 顶点坐标
/
public float[] cubePositions = {
-1f, 1f, 1f,
-1f, -1f, 1f,
1f, -1f, 1f,
1f, 1f, 1f,
-1f, 1f, -1f,
-1f, -1f, -1f,
1f, -1f, -1f,
1f, 1f, -1f
};
//6个面，一个面六个点
public short intdex[]={
6,7,4,6,4,5,
6,3,7,6,2,3,
6,5,1,6,1,2,
0,3,2,0,2,1,
0,1,5,0,5,4,
0,7,3,0,4,7
};
public float color[] = {
// (1111代表白色）颜色排列：RGB A
1f, 1f, 1f, 1f,
0f, 1f, 0f, 1f,
1f, 1f, 0f, 1f,
1f, 0f, 1f, 1f,
0f, 0f, 1f, 1f,
0f, 0f, 0.5f, 1f,
1f, 1f, 1f, 1f,
0.5f, 0f, 0f, 1f,
};
/*
* 顶点着色器
/
public final String vertexShaderCode =
"attribute vec4 vPosition;" +//声明一个用attribute修饰的变量（顶点）
"uniform mat4 vMatrix;" +//总变换矩阵
"varying vec4 vColor;" +//颜色易变变量（成对出现）
"attribute vec4 aColor;" +//声明一个用attribute修饰的变量（颜色）
"void main() {" +
" gl_Position = vMatrixvPosition;" +//根据总变换的矩阵计算绘制此顶点的位置
" vColor=aColor;" + //将接收的颜色传递给片元着色器
"}";
/**
* @Effect 片段着色器;
*/
public final String fragmentShaderCode =
// 片元语言没有默认浮点精度修饰符
// 因此，对于浮点数，浮点数向量和矩阵变量声明，
// 要么声明必须包含一个精度修饰符，要么不默认精度修饰符在之前 已经被声明过。
"precision mediump float;" +//预定义的全局默认精度
"varying vec4 vColor;" +//接收从顶点着色器过来的参数
"void main() {" +
" gl_FragColor = vColor;" + //给此片源颜色值
"}";

/**
 * @param shaderType(着色器类型,顶点和片元);
 * @param shaderCode(着色器代码);
 * @return 返回着色器对象
 * @Effect 加载Shader的方法;
 */
public int loadShader(int shaderType, String shaderCode) {
    //根据type创建顶点着色器或者片元着色器
    int shader = GLES20.glCreateShader(shaderType);
    //将资源加入到着色器中，并编译
    GLES20.glShaderSource(shader, shaderCode);
    GLES20.glCompileShader(shader);
    return shader;
}


/**
 * @param ver_Tex(数组,一般为顶点数据);
 * @return Float型缓冲
 * @Effect 获取FloatBuffer数据缓冲;
 */
public FloatBuffer getFloatBuffer(float ver_Tex[]) {
    //创建顶点坐标数据缓冲
    // vc.length*4是因为一个整数四个字节
    ByteBuffer bb = ByteBuffer.allocateDirect(ver_Tex.length * 4);
    //设置字节顺序
    // 由于不同平台字节顺序不同数据单元不是字节的一定要经过ByteBuffer转换
    bb.order(ByteOrder.nativeOrder());
    //转换为Float型缓冲
    FloatBuffer vertexBuffer = bb.asFloatBuffer();
    //向缓冲区中放入顶点坐标数据
    vertexBuffer.put(ver_Tex);
    //设置缓冲区起始位置
    vertexBuffer.position(0);
    return vertexBuffer;
}

/**
 * @param index(这个是绘制顶点的索引数组);
 * @return Short型缓冲
 * @Effect 获取ShortBuffer数据缓冲;
 */
public ShortBuffer getShortBuffer(short index[]) {
    ByteBuffer cc = ByteBuffer.allocateDirect(index.length * 2);
    cc.order(ByteOrder.nativeOrder());
    ShortBuffer indexBuffer = cc.asShortBuffer();
    indexBuffer.put(index);
    indexBuffer.position(0);
    return indexBuffer;
}

}