写一个OpenGL ES 纹理从上到下循环流动的Android demo

好的，我理解了你的问题，以下是 OpenGL ES 纹理从上到下循环流动的 Android demo：

1. 首先，我们需要在 Android Studio 中创建一个新项目。
2. 在项目中创建一个名为“texture.glsl”的文件，并在其中添加以下代码：

vertexShaderCode：

attribute vec4 position;
attribute vec2 textureCoordinate;
varying vec2 vTextureCoord;
void main() {
    gl_Position = position;
    vTextureCoord = textureCoordinate;
}

fragmentShaderCode：

precision mediump float;
uniform sampler2D uTexture;
varying vec2 vTextureCoord;
uniform float uTime;
void main() {
    vec2 uv = vec2(vTextureCoord.x, vTextureCoord.y + uTime);
    if (uv.y > 1.0) {
        uv.y -= 1.0;
    }
    vec4 textureColor = texture2D(uTexture, uv);
    gl_FragColor = textureColor;
}

3. 接下来，在项目中创建一个名为“TextureRenderer.java”的类，并在其中添加以下代码：

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.opengl.GLUtils;
import android.os.SystemClock;

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

public class TextureRenderer implements GLSurfaceView.Renderer {

    private Context context;

    private int textureId;
    private int program;
    private int positionHandle;
    private int textureCoordinateHandle;
    private int uTextureHandle;
    private int uTimeHandle;

    private float[] vertices = {
            -1f, -1f,
            1f, -1f,
            -1f, 1f,
            1f, 1f
    };

    private float[] textureCoords = {
            0f, 1f,
            1f, 1f,
            0f, 0f,
            1f, 0f
    };

    private Bitmap bitmap;

    public TextureRenderer(Context context) {
        this.context = context;
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        gl.glClearColor(0f, 0f, 0f, 1f);
        createProgram();
        createTexture();
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
        GLES20.glViewport(0, 0, width, height);
    }

    @Override
    public void onDrawFrame(GL10 gl) {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        GLES20.glUseProgram(program);

        long time = SystemClock.uptimeMillis();
        float seconds = time / 1000f;
        float timeValue = seconds % 1.0f;

        GLES20.glUniform1f(uTimeHandle, timeValue);
        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
        GLES20.glUniform1i(uTextureHandle, 0);

        GLES20.glVertexAttribPointer(
                positionHandle,
                2,
                GLES20.GL_FLOAT,
                false,
                0,
                VertexArrayHelper.createFloatBuffer(vertices)
        );
        GLES20.glEnableVertexAttribArray(positionHandle);

        GLES20.glVertexAttribPointer(
                textureCoordinateHandle,
                2,
                GLES20.GL_FLOAT,
                false,
                0,
                VertexArrayHelper.createFloatBuffer(textureCoords)
        );
        GLES20.glEnableVertexAttribArray(textureCoordinateHandle);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

        GLES20.glDisableVertexAttribArray(positionHandle);
        GLES20.glDisableVertexAttribArray(textureCoordinateHandle);
    }

    private void createProgram() {
        String vertexShaderCode = AssetsHelper.loadShaderCode(context, "texture.glsl", "vertexShaderCode");
        String fragmentShaderCode = AssetsHelper.loadShaderCode(context, "texture.glsl", "fragmentShaderCode");

        program = GLES20.glCreateProgram();

        int vertexShader = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
        GLES20.glShaderSource(vertexShader, vertexShaderCode);
        GLES20.glCompileShader(vertexShader);
        GLES20.glAttachShader(program, vertexShader);

        int fragmentShader = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);
        GLES20.glShaderSource(fragmentShader, fragmentShaderCode);
        GLES20.glCompileShader(fragmentShader);
        GLES20.glAttachShader(program, fragmentShader);

        GLES20.glLinkProgram(program);

        positionHandle = GLES20.glGetAttribLocation(program, "position");
        textureCoordinateHandle = GLES20.glGetAttribLocation(program, "textureCoordinate");
        uTextureHandle = GLES20.glGetUniformLocation(program, "uTexture");
        uTimeHandle = GLES20.glGetUniformLocation(program, "uTime");
    }

    private void createTexture() {
        bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.texture);

        int[] textureIds = new int[1];
        GLES20.glGenTextures(1, textureIds, 0);
        textureId = textureIds[0];

        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);

        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_NEAREST);

        GLES20.glTexParameteri(
                GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_WRAP_S,
                GLES20.GL_REPEAT
        );
        GLES20.glTexParameteri(
                GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_WRAP_T,
                GLES20.GL_REPEAT
        );

        GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
        bitmap.recycle();
    }
}

4. 最后，在 MainActivity 中，添加以下代码：

public class MainActivity extends AppCompatActivity {

    private GLSurfaceView glSurfaceView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        glSurfaceView = findViewById(R.id.gl_surface_view);
        glSurfaceView.setEGLContextClientVersion(2);
        glSurfaceView.setRenderer(new TextureRenderer(this));
        glSurfaceView.setRenderMode(GLSurfaceView.RENDERMODE_CONTINUOUSLY);
    }
}

5. 运行应用程序，您将看到纹理从上到下循环流动的效果。

希望这个demo能够帮到你。