Rotate3DAnimation.java 文件源码

/**
 * 执行顺序 matrix.preTranslate() -->  camera.rotateY(degrees) -->   matrix.postTranslate() -->   matrix.postScale()
 * @param interpolatedTime
 * @param t
 */
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
    float degrees = mReverse ? mToDegrees + (mFromDegrees - mToDegrees) * interpolatedTime : mFromDegrees + (mToDegrees - mFromDegrees) * interpolatedTime;
    final Matrix matrix = t.getMatrix();

    final Camera camera = mCamera;

    camera.save();

    camera.rotateY(degrees);

    camera.getMatrix(matrix);
    camera.restore();

    matrix.preTranslate(-mPivotXValue, 0);      //在进行rotateY之前需要移动物体，让物体左边与Y轴对齐
    matrix.postTranslate(mPivotXValue, 0);      //还原物体位置

    if (mReverse) {
        matrix.postScale(1 + (scaleTimes - 1) * (1.0f - interpolatedTime), 1 + (scaleTimes - 1) * (1.0f - interpolatedTime), mPivotX, mPivotY);
    } else {
        matrix.postScale(1 + (scaleTimes - 1) * interpolatedTime, 1 + (scaleTimes - 1) * interpolatedTime, mPivotX, mPivotY);
    }
}