OpenGL ES -＞ SurfaceView + EGL实现立方体纹理贴图+透视效果

XML文件

<?xml version="1.0" encoding="utf-8"?>
<com.example.myapplication.MySurfaceView 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Activity代码

class MainActivity7 : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main7)
    }
}

// 立方体信息数据类
data class CubeInfo(
    var x: Float,       // x位置
    var y: Float,       // y位置
    var angle: Float,   // 当前旋转角度
    var rotationSpeed: Float,  // 旋转速度
    var scale : Float   // 缩放
)

// 添加五个立方体的数组
private val cubes = arrayOf(
    CubeInfo(x = -1.0f, y = 1.0f, angle = 0f, rotationSpeed = 0.3f, scale = 0.3f),
    CubeInfo(x = 1.0f, y = 1.0f, angle = 45f, rotationSpeed = 0.5f, scale = 0.4f),
    CubeInfo(x = 0f, y = 0f, angle = 90f, rotationSpeed = 0.7f, scale = 0.2f),
    CubeInfo(x = -1.0f, y = -1.0f, angle = 135f, rotationSpeed = 0.4f, scale = 0.5f),
    CubeInfo(x = 1.0f, y = -1.0f, angle = 180f, rotationSpeed = 0.2f, scale = 0.7f)
)

SurfaceView代码+渲染线程代码

class MySurfaceView(context: Context, attrs: AttributeSet) : SurfaceView(context, attrs),
    SurfaceHolder.Callback {
    init {
        holder.addCallback(this)
    }

    private var mEGLThread: MyEGLThread? = null
    private var mEGLHelper = MyEGLHelper()
    private var mEGLRender = MyEGLRender(context)

    override fun surfaceCreated(holder: SurfaceHolder) {
        // 创建并启动渲染线程
        mEGLThread = MyEGLThread(holder.surface).apply {
            start()
        }
    }

    override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {
        mEGLThread?.changeSize(width, height)
    }

    override fun surfaceDestroyed(holder: SurfaceHolder) {
        mEGLThread?.release()
    }

    inner class MyEGLThread(private val mSurface: Surface) : Thread() {
        private var mWidth = 0
        private var mHeight = 0

        @Volatile
        private var mRunning = true

        @Volatile
        private var mSizeChanged = false
        override fun run() {
            super.run()
            try {
                mEGLHelper.initEGL(mSurface)
                mEGLRender.onSurfaceCreated()
                while (mRunning) {
                    // 宽高变化，回调渲染器的onSurfaceChanged方法
                    if (mSizeChanged) {
                        mEGLRender.onSurfaceChanged(mWidth, mHeight)
                        mSizeChanged = false
                    }
                    // 渲染一帧, 回调渲染器的onDrawFrame方法
                    mEGLRender.onDrawFrame()
                    mEGLHelper.swapBuffer()
                }
            } catch (e: Exception) {
                Log.e("yang", "EGL thread error ${e.message}")
            }
        }

        fun changeSize(width: Int, height: Int) {
            mWidth = width
            mHeight = height
            mSizeChanged = true
        }

        fun release() {
            mRunning = false
            mEGLRender.onSurfaceDestroyed()
            mEGLHelper.releaseEGL()
            interrupt()
        }
    }
}

EGL工具类代码

class MyEGLHelper {
    private lateinit var mEGL: EGL10
    private lateinit var mEGLDisplay: EGLDisplay
    private lateinit var mEGLContext: EGLContext
    private lateinit var mEGLSurface: EGLSurface

    // 初始化EGL
    fun initEGL(surface: Surface) {
        if (::mEGL.isInitialized &&
            ::mEGLDisplay.isInitialized &&
            ::mEGLContext.isInitialized &&
            ::mEGLSurface.isInitialized) {
            Log.e("yang", "EGL already initialized")
            return
        }
        // 1. 获取EGL实例
        mEGL = EGLContext.getEGL() as EGL10

        // 2. 获取默认的显示设备（就是窗口）
        mEGLDisplay = mEGL.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY)
        takeIf { mEGLDisplay == EGL10.EGL_NO_DISPLAY }?.apply {
            throw RuntimeException("eglGetDisplay failed")
        }

        // 3. 初始化默认显示设备
        val version = IntArray(2)
        takeIf { !mEGL.eglInitialize(mEGLDisplay, version) }?.apply {
            throw RuntimeException("eglInitialize failed")
        }

        // 4. 设置显示设备的属性
        val display_attribute_list = intArrayOf(
            EGL_RED_SIZE, 8,
            EGL_GREEN_SIZE, 8,
            EGL_BLUE_SIZE, 8,
            EGL_ALPHA_SIZE, 8,
            EGL_DEPTH_SIZE, 8,
            EGL_STENCIL_SIZE, 4,
            EGL_NONE
        )

        // 5. 查找配置并进行 attribute_list 的匹配, 匹配成功返回一个数组
        val num_config = IntArray(1)
        takeIf {
            !mEGL.eglChooseConfig(
                mEGLDisplay,
                display_attribute_list,
                null,
                0,
                num_config
            )
        }?.apply {
            throw RuntimeException("eglChooseConfig failed")
        }
        // 匹配是否成功
        takeIf { num_config[0] <= 0 }?.apply {
            throw RuntimeException("eglChooseConfig#1 failed")
        }
        val eglConfigs = arrayOfNulls<EGLConfig>(num_config[0])

        takeIf {
            !mEGL.eglChooseConfig(
                mEGLDisplay,
                display_attribute_list,
                eglConfigs,
                num_config[0],
                num_config
            )
        }?.apply {
            throw RuntimeException("eglChooseConfig#2 failed")
        }

        // 6. 创建EGLContext
        val context_display_list = intArrayOf(
            EGL_CONTEXT_CLIENT_VERSION, 3,
            EGL_NONE
        )
        takeIf { ::mEGLContext.isInitialized == false }?.apply {
            mEGLContext = mEGL.eglCreateContext(
                mEGLDisplay,
                eglConfigs[0],
                EGL10.EGL_NO_CONTEXT,
                context_display_list
            )
        }
        takeIf { mEGLContext == EGL10.EGL_NO_CONTEXT }?.apply {
            throw RuntimeException("eglCreateContext failed")
        }

        // 7. 创建EGLSurface
        takeIf { ::mEGLSurface.isInitialized == false }?.apply {
            mEGLSurface = mEGL.eglCreateWindowSurface(mEGLDisplay, eglConfigs[0], surface, null)
        }
        takeIf { mEGLSurface == EGL10.EGL_NO_SURFACE }?.apply {
            throw RuntimeException("eglCreateWindowSurface failed")
        }

        // 8. 绑定EGLContext和EGLSurface
        takeIf { !mEGL.eglMakeCurrent(mEGLDisplay, mEGLSurface, mEGLSurface, mEGLContext) }?.apply {
            throw RuntimeException("eglMakeCurrent failed")
        }
    }

    // 释放EGL
    fun releaseEGL() {
        takeIf { ::mEGL.isInitialized }?.apply {
            // 解绑EGLContext和EGLSurface
            mEGL.eglMakeCurrent(
                mEGLDisplay,
                EGL10.EGL_NO_SURFACE,
                EGL10.EGL_NO_SURFACE,
                EGL10.EGL_NO_CONTEXT
            )
            // 释放EGLSurface
            mEGL.eglDestroySurface(mEGLDisplay, mEGLSurface)
            // 释放EGLContext
            mEGL.eglDestroyContext(mEGLDisplay, mEGLContext)
            // 释放EGLDisplay
            mEGL.eglTerminate(mEGLDisplay)
        }
    }

    // 交换渲染数据
    fun swapBuffer() {
        takeIf { ::mEGL.isInitialized && ::mEGLDisplay.isInitialized }?.apply {
            takeIf { !mEGL.eglSwapBuffers(mEGLDisplay, mEGLSurface) }?.apply {
                throw RuntimeException("eglSwapBuffers failed")
            }
        }
    }
}

渲染器接口

interface EGLRender {
    fun onSurfaceCreated()
    fun onSurfaceChanged(width: Int, height: Int)
    fun onDrawFrame()
    fun onSurfaceDestroyed()
}

渲染器实现类

class MyEGLRender(private val mContext: Context) : EGLRender {
    var mDrawData: MyDrawData2? = null

    override fun onSurfaceCreated() {
        GLES30.glClearColor(0.0f, 0.5f, 0.5f, 1.0f)
        mDrawData = MyDrawData2().apply {
            initTexture0(mContext, R.drawable.picture)
            initShaderProgram()
            initVertexBuffer()
        }
    }

    override fun onSurfaceChanged(width: Int, height: Int) {
        GLES30.glViewport(0, 0, width, height)
        mDrawData?.setSurfaceSize(width, height)
    }

    override fun onDrawFrame() {
        GLES30.glEnable(GLES30.GL_DEPTH_TEST)
        GLES30.glClear(GLES30.GL_COLOR_BUFFER_BIT or GLES30.GL_DEPTH_BUFFER_BIT)
        mDrawData?.drawCurrentOutput()
    }

    override fun onSurfaceDestroyed() {
        mDrawData?.release()
    }
}

渲染器实现类需要的绘制数据

class MyDrawData2 {
    private var mProgram: Int = -1
    private var NO_OFFSET = 0
    private val VERTEX_POS_DATA_SIZE = 3
    private val TEXTURE_POS_DATA_SIZE = 2
    private val STRIDE = (VERTEX_POS_DATA_SIZE + TEXTURE_POS_DATA_SIZE) * 4 // 每个顶点的总字节数

    // VAO(Vertex Array Object), 顶点数组对象, 用于存储VBO
    private var mVAO = IntArray(1)

    // VBO(Vertex Buffer Object), 顶点缓冲对象，用于存储顶点数据和纹理数据
    private var mVBO = IntArray(1) // 只需要一个VBO

    // 纹理ID
    private var mTextureID = IntArray(1)

    // 最终变换矩阵
    private var mMVPMatrix = FloatArray(16)

    // 投影矩阵
    private val mProjectionMatrix = FloatArray(16)

    // 视图矩阵
    private val mViewMatrix = FloatArray(16)

    // 模型矩阵
    private val mModelMatrix = FloatArray(16)

    // 视口比例
    private var mViewPortRatio = 1f

    // Surface宽高
    private var mSurfaceWidth = 0
    private var mSurfaceHeight = 0

    // 顶点和纹理坐标合并在一个数组中
    // 格式：x, y, z, u, v (顶点坐标后跟纹理坐标)
    val vertexData = floatArrayOf(
        // 顶点坐标            // 纹理坐标
        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,
        0.5f, -0.5f, -0.5f,  1.0f, 0.0f,
        0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 0.0f,

        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
        0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
        0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
        0.5f,  0.5f,  0.5f,  1.0f, 1.0f,
        -0.5f,  0.5f,  0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,

        -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

        0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
        0.5f,  0.5f,  0.5f,  1.0f, 0.0f,

        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,
        0.5f, -0.5f, -0.5f,  1.0f, 1.0f,
        0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
        0.5f, -0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f, -0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f, -0.5f, -0.5f,  0.0f, 1.0f,

        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f,
        0.5f,  0.5f, -0.5f,  1.0f, 1.0f,
        0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        0.5f,  0.5f,  0.5f,  1.0f, 0.0f,
        -0.5f,  0.5f,  0.5f,  0.0f, 0.0f,
        -0.5f,  0.5f, -0.5f,  0.0f, 1.0f
    )

    val vertexDataBuffer = ByteBuffer.allocateDirect(vertexData.size * 4)
        .order(ByteOrder.nativeOrder())
        .asFloatBuffer()
        .put(vertexData)
        .position(NO_OFFSET)

    // 初始化着色器程序
    fun initShaderProgram() {
        val vertexShaderCode = """#version 300 es
            uniform mat4 uMVPMatrix; // 变换矩阵
            in vec4 aPosition; // 顶点坐标
            in vec2 aTexCoord; // 纹理坐标 
            out vec2 vTexCoord; 
            void main() {
                // 输出顶点坐标和纹理坐标到片段着色器
                gl_Position = uMVPMatrix * aPosition;
                vTexCoord = aTexCoord;
            }""".trimIndent()
        val fragmentShaderCode = """#version 300 es
         precision mediump float;
         uniform sampler2D uTexture_0;
         in vec2 vTexCoord;
         out vec4 fragColor;
         void main() {
             fragColor = texture(uTexture_0, vTexCoord);
         }""".trimIndent()

        // 加载顶点着色器和片段着色器, 并创建着色器程序
        val vertexShader = LoadShaderUtil.loadShader(GLES30.GL_VERTEX_SHADER, vertexShaderCode)
        val fragmentShader = LoadShaderUtil.loadShader(GLES30.GL_FRAGMENT_SHADER, fragmentShaderCode)
        mProgram = GLES30.glCreateProgram()
        GLES30.glAttachShader(mProgram, vertexShader)
        GLES30.glAttachShader(mProgram, fragmentShader)
        GLES30.glLinkProgram(mProgram)

        // 删除着色器对象
        GLES30.glDeleteShader(vertexShader)
        GLES30.glDeleteShader(fragmentShader)
    }

    // 创建VAO, VBO, IBO
    fun initVertexBuffer() {
        // 绑定VAO
        GLES30.glGenVertexArrays(mVAO.size, mVAO, NO_OFFSET)
        GLES30.glBindVertexArray(mVAO[0])

        // 绑定VBO - 只需要一个VBO存储所有数据
        GLES30.glGenBuffers(mVBO.size, mVBO, NO_OFFSET)
        GLES30.glBindBuffer(GLES30.GL_ARRAY_BUFFER, mVBO[0])
        GLES30.glBufferData(
            GLES30.GL_ARRAY_BUFFER,
            vertexData.size * 4,
            vertexDataBuffer,
            GLES30.GL_STATIC_DRAW
        )

        // 设置顶点属性指针 - 顶点坐标
        val positionHandle = GLES30.glGetAttribLocation(mProgram, "aPosition")
        GLES30.glEnableVertexAttribArray(positionHandle)
        GLES30.glVertexAttribPointer(
            positionHandle,
            VERTEX_POS_DATA_SIZE,
            GLES30.GL_FLOAT,
            false,
            STRIDE,     // 步长，每个顶点5个float (x,y,z,u,v)
            NO_OFFSET   // 偏移量，位置数据在前
        )

        // 设置顶点属性指针 - 纹理坐标
        val textureHandle = GLES30.glGetAttribLocation(mProgram, "aTexCoord")
        GLES30.glEnableVertexAttribArray(textureHandle)
        GLES30.glVertexAttribPointer(
            textureHandle,
            TEXTURE_POS_DATA_SIZE,
            GLES30.GL_FLOAT,
            false,
            STRIDE,                          // 步长，每个顶点5个float (x,y,z,u,v)
            VERTEX_POS_DATA_SIZE * 4         // 偏移量，纹理数据在位置数据之后
        )

        // 解绑VAO
        GLES30.glBindVertexArray(0)
        // 解绑VBO
        GLES30.glBindBuffer(GLES30.GL_ARRAY_BUFFER, 0)
    }

    // 使用着色器程序绘制图形
    fun drawSomething(program: Int, mvpMatrix: FloatArray) {
        // 解析变换矩阵
        val matrixHandle = GLES30.glGetUniformLocation(program, "uMVPMatrix")
        GLES30.glUniformMatrix4fv(matrixHandle, 1, false, mvpMatrix, NO_OFFSET)

        // 绑定VAO
        GLES30.glBindVertexArray(mVAO[0])
        // 绘制图形
        GLES30.glDrawArrays(GLES30.GL_TRIANGLES, NO_OFFSET, vertexData.size / (VERTEX_POS_DATA_SIZE + TEXTURE_POS_DATA_SIZE))
        // 解绑VAO
        GLES30.glBindVertexArray(0)
    }

    fun setSurfaceSize(width: Int, height: Int){
        mSurfaceWidth = width
        mSurfaceHeight = height
    }

    fun resetMatrix() {
        Matrix.setIdentityM(mModelMatrix, NO_OFFSET)
        Matrix.setIdentityM(mViewMatrix, NO_OFFSET)
        Matrix.setIdentityM(mProjectionMatrix, NO_OFFSET)
        Matrix.setIdentityM(mMVPMatrix, NO_OFFSET)
    }

    // 计算GLSurfaceView变换矩阵
    fun computeMVPMatrix(width: Int, height: Int, cube: CubeInfo) {
        mSurfaceWidth = width
        mSurfaceHeight = height

        // 更新立方体的旋转角度
        cube.angle += cube.rotationSpeed
        cube.angle %= 360
        Matrix.scaleM(mModelMatrix, NO_OFFSET, cube.scale, cube.scale, cube.scale)

        Matrix.translateM(mModelMatrix, NO_OFFSET, cube.x, cube.y, 0f)

        Matrix.rotateM(mModelMatrix, NO_OFFSET, cube.angle, 0.5f, 0.5f, 0f)

        val isLandscape = width > height
        mViewPortRatio = if (isLandscape) width.toFloat() / height else height.toFloat() / width

        // 计算包围图片的球半径
        val radius = sqrt(1f + mViewPortRatio * mViewPortRatio)
        val near = 0.1f
        val far = near + 2 * radius
        val distance = near / (near + radius)
        // 视图矩阵View Matrix
        Matrix.setLookAtM(
            mViewMatrix, NO_OFFSET,
            0f, 0f, near + radius,  // 相机位置
            0f, 0f, 0f,             // 看向原点
            0f, 1f, 0f              // 上方向
        )

        // 投影矩阵Projection Matrix
        Matrix.frustumM(
            mProjectionMatrix, NO_OFFSET,
            if (isLandscape) (-mViewPortRatio * distance) else (-1f * distance),  // 左边界
            if (isLandscape) (mViewPortRatio * distance) else (1f * distance),    // 右边界
            if (isLandscape) (-1f * distance) else (-mViewPortRatio  * distance),  // 下边界
            if (isLandscape) (1f * distance) else (mViewPortRatio * distance),    // 上边界
            near, // 近平面
            far // 远平面
        )

        // 最终变换矩阵，第一次变换，模型矩阵 x 视图矩阵 = Model x View, 但是OpenGL ES矩阵乘法是右乘，所以是View x Model
        Matrix.multiplyMM(
            mMVPMatrix,
            NO_OFFSET,
            mViewMatrix,
            NO_OFFSET,
            mModelMatrix,
            NO_OFFSET
        )

        // 最终变换矩阵，第二次变换，模型矩阵 x 视图矩阵 x 投影矩阵 = Model x View x Projection, 但是OpenGL ES矩阵乘法是右乘，所以是Projection x View x Model
        Matrix.multiplyMM(
            mMVPMatrix,
            NO_OFFSET,
            mProjectionMatrix,
            NO_OFFSET,
            mMVPMatrix,
            NO_OFFSET
        )

        // 纹理坐标系为(0, 0), (1, 0), (1, 1), (0, 1)的正方形逆时针坐标系，从Bitmap生成纹理，即像素拷贝到纹理坐标系
        // 变换矩阵需要加上一个y方向的翻转, x方向和z方向不改变
        Matrix.scaleM(
            mMVPMatrix,
            NO_OFFSET,
            1f,
            -1f,
            1f,
        )
    }

    // 加载纹理
    fun loadTexture(context: Context, resourceId: Int): Int {
        val textureId = IntArray(1)
        // 生成纹理
        GLES30.glGenTextures(1, textureId, 0)
        // 绑定纹理
        GLES30.glBindTexture(GLES30.GL_TEXTURE_2D, textureId[0])
        // 设置纹理参数
        GLES30.glTexParameteri(
            GLES30.GL_TEXTURE_2D,
            GLES30.GL_TEXTURE_MIN_FILTER,
            GLES30.GL_LINEAR
        ) // 纹理缩小时使用线性插值
        GLES30.glTexParameteri(
            GLES30.GL_TEXTURE_2D,
            GLES30.GL_TEXTURE_MAG_FILTER,
            GLES30.GL_LINEAR
        ) // 纹理放大时使用线性插值
        GLES30.glTexParameteri(
            GLES30.GL_TEXTURE_2D,
            GLES30.GL_TEXTURE_WRAP_S,
            GLES30.GL_CLAMP_TO_EDGE
        ) // 纹理坐标超出范围时，超出部分使用最边缘像素进行填充
        GLES30.glTexParameteri(
            GLES30.GL_TEXTURE_2D,
            GLES30.GL_TEXTURE_WRAP_T,
            GLES30.GL_CLAMP_TO_EDGE
        ) // 纹理坐标超出范围时，超出部分使用最边缘像素进行填充
        // 加载图片
        val options = BitmapFactory.Options().apply {
            inScaled = false // 不进行缩放
        }
        val bitmap = BitmapFactory.decodeResource(context.resources, resourceId, options)
        // 将图片数据加载到纹理中
        GLUtils.texImage2D(GLES30.GL_TEXTURE_2D, 0, bitmap, 0)
        // 释放资源
        bitmap.recycle()
        // 解绑纹理
        GLES30.glBindTexture(GLES30.GL_TEXTURE_2D, 0)
        Log.e(
            "yang",
            "loadTexture: 纹理加载成功 bitmap.width:${bitmap.width} bitmap.height:${bitmap.height}"
        )
        return textureId[0]
    }

    fun enableTexture0(program: Int, id: Int) {
        GLES30.glActiveTexture(GLES30.GL_TEXTURE0)
        GLES30.glBindTexture(GLES30.GL_TEXTURE_2D, id)
        val textureSampleHandle = GLES30.glGetUniformLocation(program, "uTexture_0")
        if (textureSampleHandle != -1) {
            GLES30.glUniform1i(textureSampleHandle, 0)
        }
    }

    fun disableTexture0() {
        GLES30.glActiveTexture(GLES30.GL_TEXTURE0)
        GLES30.glBindTexture(GLES30.GL_TEXTURE_2D, 0)
    }

    fun initTexture0(context: Context, resourceId: Int) {
        mTextureID[0] = loadTexture(context, resourceId)
    }


    // GLSurfaceView实时绘制
    fun drawCurrentOutput() {
        val state = saveGLState()
        try {
            GLES30.glUseProgram(mProgram)
            enableTexture0(mProgram, mTextureID[0])
            // 为每个立方体计算MVP矩阵并绘制
            for (cube in cubes) {
                resetMatrix()
                computeMVPMatrix(mSurfaceWidth, mSurfaceHeight, cube)
                drawSomething(mProgram, mMVPMatrix)
            }
            disableTexture0()
        } finally {
            restoreGLState(state)
        }
    }

    // 保存OpenGL状态
    private fun saveGLState(): GLState {
        val viewport = IntArray(4)
        val program = IntArray(1)
        val framebuffer = IntArray(1)
        GLES30.glGetIntegerv(GLES30.GL_VIEWPORT, viewport, 0)
        GLES30.glGetIntegerv(GLES30.GL_CURRENT_PROGRAM, program, 0)
        GLES30.glGetIntegerv(GLES30.GL_FRAMEBUFFER_BINDING, framebuffer, 0)
        return GLState(viewport, program[0], framebuffer[0])
    }

    // 恢复OpenGL状态
    private fun restoreGLState(state: GLState) {
        GLES30.glViewport(
            state.viewport[0],
            state.viewport[1],
            state.viewport[2],
            state.viewport[3]
        )
        GLES30.glUseProgram(state.program)
        GLES30.glBindFramebuffer(GLES30.GL_FRAMEBUFFER, state.framebuffer)
    }


    fun release(){
        // 删除VAO
        if (mVAO[0] != 0) {
            GLES30.glDeleteVertexArrays(1, mVAO, 0)
            mVAO[0] = 0
        }

        // 删除VBO
        if (mVBO[0] != 0) {
            GLES30.glDeleteBuffers(1, mVBO, 0)
            mVBO[0] = 0
        }

        // 删除纹理
        if (mTextureID[0] != 0) {
            GLES30.glDeleteTextures(1, mTextureID, 0)
            mTextureID[0] = 0
        }


        // 删除着色器程序
        if (mProgram != -1) {
            GLES30.glDeleteProgram(mProgram)
            mProgram = -1
        }

        // 清空缓冲区
        vertexDataBuffer.clear()
    }

    // OpenGL状态数据类
    data class GLState(
        val viewport: IntArray,
        val program: Int,
        val framebuffer: Int
    )

    object LoadShaderUtil {
        // 创建着色器对象
        fun loadShader(type: Int, source: String): Int {
            val shader = GLES30.glCreateShader(type)
            GLES30.glShaderSource(shader, source)
            GLES30.glCompileShader(shader)
            return shader
        }
    }
}

效果图