如何在ARCore中使用OpenGL为单个3D对象加载多张2D纹理

Core Idea to Build On #

Your single-texture code already covers the essential OpenGL texture workflow—we just need to scale this to handle multiple textures by assigning each a unique ID, using separate texture units, and repeating the setup steps for every texture asset.

Full Implementation Code #

First, set up your texture ID array and list of texture asset names:

// Array to store unique IDs for each texture
private int[] mTextures;
// Replace with your actual texture asset filenames (e.g., diffuse, specular, normal maps)
private String[] textureAssetNames = {"diffuse_tex.png", "specular_tex.png", "normal_tex.png"};

Then create a method to load all textures in one go:

public void loadMultipleTextures(Context context) {
    // Initialize the texture ID array with the number of textures we need
    mTextures = new int[textureAssetNames.length];
    
    // Generate all texture IDs upfront
    GLES20.glGenTextures(mTextures.length, mTextures, 0);
    
    for (int i = 0; i < textureAssetNames.length; i++) {
        try {
            // Load the bitmap from the app's assets folder
            Bitmap textureBitmap = BitmapFactory.decodeStream(
                context.getAssets().open(textureAssetNames[i])
            );
            
            // Activate the corresponding texture unit (GL_TEXTURE0, GL_TEXTURE1, etc.)
            GLES20.glActiveTexture(GLES20.GL_TEXTURE0 + i);
            
            // Bind the current texture ID to the active unit
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextures[i]);
            
            // Apply texture filtering parameters (matches your original single-texture setup)
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR_MIPMAP_LINEAR);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
            
            // Load the bitmap data into the bound texture
            GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, textureBitmap, 0);
            
            // Generate mipmaps for smoother rendering at different distances
            GLES20.glGenerateMipmap(GLES20.GL_TEXTURE_2D);
            
            // Free up memory by recycling the bitmap (no longer needed after loading)
            textureBitmap.recycle();
            
            // Unbind the texture to avoid accidental modifications in subsequent code
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
            
        } catch (IOException e) {
            e.printStackTrace();
            // Add custom error handling here (e.g., load a fallback default texture)
        }
    }
}

Using the Textures in Rendering #

When drawing your 3D object, you need to bind each texture and pass its unit index to your shader:

// In your object's draw method
for (int i = 0; i < mTextures.length; i++) {
    // Activate the correct texture unit
    GLES20.glActiveTexture(GLES20.GL_TEXTURE0 + i);
    // Bind the texture to the active unit
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextures[i]);
    // Tell the shader which unit to use for this texture (match your shader's uniform names)
    int uniformLoc = GLES20.glGetUniformLocation(mShaderProgram, "uTexture" + i);
    GLES20.glUniform1i(uniformLoc, i);
}

// Proceed with drawing your object (glDrawArrays or glDrawElements)

Quick Notes #

• Ensure your shader has matching uniform samplers (e.g., uniform sampler2D uTexture0; uniform sampler2D uTexture1;).
• Always recycle bitmaps after loading to prevent memory leaks in Android.
• You can expand error handling to gracefully handle missing texture assets (e.g., fall back to a solid color texture).

内容的提问来源于stack exchange，提问作者Raj