Android OpenGL SurfaceTexture(外部图像)与普通纹理的结合

Question

我想将相机预览 SurfaceTexture 与一些覆盖纹理混合。我正在使用这些着色器进行处理:

private final String vss = "attribute vec2 vPosition;\n"
        + "attribute vec2 vTexCoord;\n"
        + "varying vec2 texCoord;\n"
        + "void main() {\n" 
        + "  texCoord = vTexCoord;\n"
        + "  gl_Position = vec4 ( vPosition.x, vPosition.y, 0.0, 1.0 );\n"
        + "}";

private final String fss = "#extension GL_OES_EGL_image_external : require\n"
        + "precision mediump float;\n"
        + "uniform samplerExternalOES sTexture;\n"
        + "uniform sampler2D filterTexture;\n"
        + "varying vec2 texCoord;\n"
        + "void main() {\n"
        +"  vec4 t_camera = texture2D(sTexture,texCoord);\n"
        //+"  vec4 t_overlayer = texture2D(filterTexture, texCoord);\n" 
        //+ "  gl_FragColor = t_overlayer;\n" + "}";
        + "  gl_FragColor = t_camera;\n" + "}";

我的目标是混合使用 t_camera 和 t_overlayer。当我分别显示 t_camera 或 t_overlayer 时，它起作用了(显示相机预览或纹理)。但是，当我取消注释 t_overlayer 时，t_camera 会变成黑色(采样率不佳)。我的覆盖层纹理是 512x512 和 CLAMPT_TO_EDGE。此问题仅在以下示例中发生:Android Emulator、HTC Evo 3D。但在 SGS3、HTC One X 上，它工作得很好。

怎么了？是 Evo 3D 缺少某些扩展还是什么？

Answer 1

我想您遇到这个问题是因为您没有在代码中设置正确的纹理 ID。这是一个典型的假设错误，看似合乎逻辑，但实际上文档中并未如此定义。如果您查看此扩展的文档，您会看到以下(编辑过的)文本:

Each TEXTURE_EXTERNAL_OES texture object may require up to 3 texture image units for each texture unit to which it is bound. When is set to TEXTURE_EXTERNAL_OES this value will be between 1 and 3 (inclusive). For other valid texture targets this value will always be 1. Note that, when a TEXTURE_EXTERNAL_OES texture object is bound, the number of texture image units required by a single texture unit may be 1, 2, or 3, while for other texture objects each texture unit requires exactly 1 texture image unit.

这意味着至少还有一个可以工作，前提是您使用 id 0。在你的情况下:

GLES20.glUniform1i(sTextureHandle, 1);
GLES20.glActiveTexture(GLES20.GL_TEXTURE1);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,
        sTextureId);

对于您的 2D 纹理:

GLES20.glUniform1i(filterTextureHandle, 0);
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, filterTextureID);

我相信这会适合你。