android - 使用视频流作为开放的 GL ES 2.0 纹理

Question

我正在尝试通过将 Open GL ES 纹理设置为 android surfaceTexture 来捕获视频并将其显示到屏幕上.我不能使用 TextureView并实现 SurfaceTextureListener根据 this tutorial因为我使用的是 Google Cardboard。

我关注了the Android documentation关于如何初始化 Open GL ES 2.0 和使用它，以及 this tutorial关于纹理。

将 2 放在一起我得到一个空白屏幕，偶尔会得到 <core_glBindTexture:572>: GL_INVALID_OPERATION在控制台窗口中。

被这么多我不知道的新概念所淹没，我无法调试或者只是理解这两种方法是否可以这样使用。这是我的绘图代码，它在 onSurfaceCreated() 中初始化的 MainActivity类，并取自 onEyeDraw()这是 Cardboard 的绘图功能。

package com.example.rich.test3;

import android.hardware.Camera;
import android.opengl.GLES20;
import android.view.TextureView;

import java.nio.ShortBuffer;
import java.nio.FloatBuffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

/**
 * Created by rich on 03/05/2015.
 */
public class Square {

private java.nio.FloatBuffer vertexBuffer;
private java.nio.ShortBuffer drawListBuffer;
private final java.nio.FloatBuffer mCubeTextureCoordinates;

float color[] = { 1.f, 1.f, 1.f, 1.0f };

private final String vertexShaderCode =
        "attribute vec4 vPosition;" +
        "attribute vec2 a_TexCoordinate;" +
        "varying vec2 v_TexCoordinate;" +
                "void main() {" +
                " gl_Position = vPosition;" +
                " v_TexCoordinate = a_TexCoordinate;" +
                "}";

private final String fragmentShaderCode =
        "precision mediump float;" +
                "uniform vec4 vColor;" +
                "uniform sampler2D u_Texture;" +
                "varying vec2 v_TexCoordinate;" +
                "void main() {" +
                "gl_FragColor = (texture2D(u_Texture, v_TexCoordinate));" +
                "}";

// number of coordinates per vertex in this array
static final int COORDS_PER_VERTEX = 3;
static float squareCoords[] = {
        -0.5f, -0.5f, 0.0f,   // bottom left
        0.5f, -0.5f, 0.0f,   // bottom right
        -0.5f,  0.5f, 0.0f,   // top left
        0.5f,  0.5f, 0.0f}; // top right

private short drawOrder[] = { 0, 1, 2, 0, 2, 3 }; // order to draw vertices

private int mProgram;

private int mPositionHandle;
private int mColorHandle;
private int mTextureUniformHandle;
private int mTextureCoordinateHandle;
private final int mTextureCoordinateDataSize = 2;

private final int vertexCount = squareCoords.length / COORDS_PER_VERTEX;
private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex

private int mTextureDataHandle;

float textureCoordinates[] =
        {0.0f, 1.0f,
        1.0f, 1.0f,
        0.0f, 0.0f,
        1.0f, 0.0f };

Camera _camera;
TextureView _textureView;
int[] textures;
android.graphics.SurfaceTexture _surface;

public Square()
{
    ByteBuffer bb = ByteBuffer.allocateDirect(
            // (# of coordinate values * 4 bytes per float)
            squareCoords.length * 4);
    bb.order(ByteOrder.nativeOrder());
    vertexBuffer = bb.asFloatBuffer();
    vertexBuffer.put(squareCoords);
    vertexBuffer.position(0);

    // initialize byte buffer for the draw list
    ByteBuffer dlb = ByteBuffer.allocateDirect(
            // (# of coordinate values * 2 bytes per short)
            drawOrder.length * 2);
    dlb.order(ByteOrder.nativeOrder());
    drawListBuffer = dlb.asShortBuffer();
    drawListBuffer.put(drawOrder);
    drawListBuffer.position(0);

    mCubeTextureCoordinates = ByteBuffer.allocateDirect(textureCoordinates.length * 4)
            .order(ByteOrder.nativeOrder()).asFloatBuffer();
    mCubeTextureCoordinates.put(textureCoordinates).position(0);

    // create empty OpenGL ES Program
    mProgram = GLES20.glCreateProgram();

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

    _surface = new android.graphics.SurfaceTexture(textures[0]);
    _camera = Camera.open();
    Camera.Size previewSize = _camera.getParameters().getPreviewSize();

    try
    {
        _camera.setPreviewTexture(_surface);
    }
    catch (java.io.IOException ex)
    {
        // Console.writeLine (ex.Message);
    }

    final int vertexShaderHandle = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
    GLES20.glShaderSource(vertexShaderHandle, vertexShaderCode);
    GLES20.glCompileShader(vertexShaderHandle);
    final int[] compileStatus = new int[1];
    GLES20.glGetShaderiv(vertexShaderHandle, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
    if (compileStatus[0] == 0)
    {
        //do check here
    }

    final int fragmentShaderHandle = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);
    GLES20.glShaderSource(fragmentShaderHandle, fragmentShaderCode);
    GLES20.glCompileShader(fragmentShaderHandle);
    GLES20.glGetShaderiv(fragmentShaderHandle, GLES20.GL_COMPILE_STATUS, compileStatus, 0);
    if (compileStatus[0] == 0)
    {
        //do check here
    }

    GLES20.glAttachShader(mProgram, vertexShaderHandle);
    GLES20.glAttachShader(mProgram, fragmentShaderHandle);
    GLES20.glBindAttribLocation(mProgram, 0, "a_Position");
    GLES20.glBindAttribLocation(mProgram, 0, "a_TexCoordinate");

    GLES20.glLinkProgram(mProgram);
    final int[] linkStatus = new int[1];
    GLES20.glGetProgramiv(mProgram, GLES20.GL_LINK_STATUS, linkStatus, 0);
    if (linkStatus[0] == 0)
    {
        //do check here
    }

    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textures[0]);
    mTextureDataHandle = textures[0];

    // Set filtering
    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);
}

public void draw()
{
    _surface.updateTexImage();
    GLES20.glUseProgram(mProgram);

    mTextureUniformHandle = GLES20.glGetUniformLocation(mProgram, "u_Texture");
    mPositionHandle = GLES20.glGetAttribLocation(mProgram, "a_Position");
    mColorHandle = GLES20.glGetAttribLocation(mProgram, "a_Color");
    mTextureCoordinateHandle = GLES20.glGetAttribLocation(mProgram, "a_TexCoordinate");

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

    GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX,
            GLES20.GL_FLOAT, false,
            vertexStride, vertexBuffer);
    GLES20.glVertexAttribPointer(mTextureCoordinateHandle, mTextureCoordinateDataSize, GLES20.GL_FLOAT, false,
            0, mCubeTextureCoordinates);

    GLES20.glEnableVertexAttribArray(mTextureCoordinateHandle);
    GLES20.glEnableVertexAttribArray(mPositionHandle);
    GLES20.glUniform1i(mTextureUniformHandle, 0);

    GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, vertexCount);
    GLES20.glDisableVertexAttribArray(mPositionHandle);
}

}

Answer 1

渲染 SurfaceTexture 时纹理对象，您需要使用 GL_TEXTURE_EXTERNAL_OES 纹理目标:

The texture object uses the GL_TEXTURE_EXTERNAL_OES texture target, which is defined by the GL_OES_EGL_image_external OpenGL ES extension. This limits how the texture may be used. Each time the texture is bound it must be bound to the GL_TEXTURE_EXTERNAL_OES target rather than the GL_TEXTURE_2D target. Additionally, any OpenGL ES 2.0 shader that samples from the texture must declare its use of this extension using, for example, an "#extension GL_OES_EGL_image_external : require" directive. Such shaders must also access the texture using the samplerExternalOES GLSL sampler type.

因此您需要像这样更改 fragment 着色器，添加 #extension 声明并将纹理统一声明为 samplerExternalOES:

private final String fragmentShaderCode =
    "#extension GL_OES_EGL_image_external : require\n" +
    "precision mediump float;" +
    "uniform vec4 vColor;" +
    "uniform samplerExternalOES u_Texture;" +
    "varying vec2 v_TexCoordinate;" +
    "void main() {" +
            "gl_FragColor = (texture2D(u_Texture, v_TexCoordinate));" +
    "}";

同样在您的 draw() 函数中，像这样绑定(bind)纹理:

GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, mTextureDataHandle);