OpenGL on Android - Texture Mapping - Only top left pixel visible

问题

I've been playing with OpenGL ES Android and somehow my textures are always filled with the color of the the top left-most pixel. I suppose the flags are wrong, but I've tried a many logical combinations and it does not seem to make any difference.

Why would the texture behave like so? What's the bit (flag bit indeed) that am I missing? Thanks

public void loadGLTexture(GL10 gl, Context context) {
    Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), resourceId);

    gl.glGenTextures(1, textures, 0);
    gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);

    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);
    gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE, GL10.GL_REPLACE);

    GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);

    bitmap.recycle();
}

public void draw(GL10 gl) {
    // bind the previously generated texture
    gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);

    ((GL11Ext) gl).glDrawTexfOES(position.getX(), position.getY(), 0, width, height);
}

the surface is set to

gl.glEnable(GL10.GL_TEXTURE_2D);
gl.glShadeModel(GL10.GL_SMOOTH);
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
gl.glClearDepthf(1.0f);
gl.glEnable(GL10.GL_DEPTH_TEST);
gl.glDepthFunc(GL10.GL_LEQUAL);
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST);

回答1:

Obviously texture crop rectangle has to be explicitly set:

int cropWorkspace[] = new int[4];
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inPreferredConfig = Bitmap.Config.RGB_565;
cropWorkspace[0] = 0;
cropWorkspace[1] = height;
cropWorkspace[2] = width;
cropWorkspace[3] = -height;

((GL11) gl).glTexParameteriv(GL10.GL_TEXTURE_2D, GL11Ext.GL_TEXTURE_CROP_RECT_OES, cropWorkspace, 0);

来源：https://stackoverflow.com/questions/7920118/opengl-on-android-texture-mapping-only-top-left-pixel-visible

标签

android

textures

opengl-es-2.0