问题描述
为了旋转/翻译对象（只有z轴和翻译仅在XY平面旋转）不只是WRT全球中心（设备中心），但也WRT其他任意点，我创建了一个算法，这是正确的（因为所有高级codeRS我曾与讨论认为是正确的），但是它采取了大量的时间来删除一个不需要翻译在执行（创建算法8月4日，并实现在同一天，此后code已被修订的15倍）。
In order to rotate/translate object (rotation only about z-axis and translation only in xy plane) not just w.r.t to global center (device center) but also w.r.t other arbitrary points, I created an algorithm, which is correct (because all senior coders I have discussed with consider it correct), but it is taking a lot of time to remove an undesired translation in the implementation (algorithm was created on August 4 and was implemented on the same day, since then the code has been revised 15 times).
下面是实施 http://www.pixdip.com/opengles/transform.php#ALGO1
Here is the implementation http://www.pixdip.com/opengles/transform.php#ALGO1
的code，它是生产不需要翻译的线条都在里面：
The lines of code that are producing undesired translation are inside:
私有静态无效的UpdateModel（INT UPDOWN，浮xAngle，浮yAngle，浮zAngle）{
和列举如下：
-
Matrix.multiplyMV（GLES20Renderer._uBodyCentreMatrix，0，GLES20Renderer._ModelMatrixBody，0，GLES20Renderer._uBodyCentre，0）
物objx = GLES20Renderer._uBodyCentreMatrix [0];
objY = GLES20Renderer._uBodyCentreMatrix [1];
即使以下更改沿+ Y的不需要翻译仍然存在：
-
objY = _uBodyCentreMatrix [1] - _uBodyCentre [1];
zAngle = 0;
DS = 0;
值 -0.545867f 添加到Y在每次调用 onDrawFrame（）协调，因为该渲染器类的这些字段：
The value -0.545867f is added to the Y coordinate on every call to onDrawFrame(), because of these fields of the Renderer class:
私有静态最终浮动[] _uBodyCentre =新的浮动[] { - 0.019683f，-0.545867f，-0.000409f，1.0F};
受保护的静态浮动[] _uBodyCentreMatrix =新的浮动[4];
在 http://www.pixdip.com/opengles/transform.php#FIELDS
我需要帮助理解为什么说不需要翻译发生，究竟是什么毛病转换，或者是它的算法是错误的。
可万向锁是一个问题吗？
请不要问我执行/练习简单的例子，因为我有prepared渲染器类旋转/翻译关于全球z轴，那我到这个新的任务，使用相同的类轻微在修改的UpdateModel（）
Please do not ask me to perform/practice simpler examples, because I have prepared the Renderer class for rotation/translation about global z-axis, and this new task that I am into, uses the same class with slight modification in updateModel()
（请注意，所需要的旋转仅约z轴和翻译仅在xy面）
(Please note that the desired rotation is only about z-axis and translation only in xy plane)
[API 10-> 15
[API 10->15]
实际的渲染器类有两个对象：坦克炮塔（喷嘴）和罐体内，同时炮塔（喷嘴）已不期望着翻译，身体已经不需要向后平移
The actual Renderer class has two objects: tank turret(nozzle) and tank body, while turret(nozzle) has undesired forward translation, the body has undesired backward translation
的.apk有关设备中心的平移/旋转（这是很容易使opengles 2.0）： http://www.pixdip.com/opengles/global.php
Apk for translation/rotation about device center (which is easy to make in opengles 2.0):http://www.pixdip.com/opengles/global.php
的.apk关于任意点的平移/旋转（已翻译不希望沿着+ Y）： http://www.pixdip.com/opengles/local.php
Apk for translation/rotation about arbitrary points (which has undesired translation along +Y):http://www.pixdip.com/opengles/local.php
的.apk关于任意点的平移/旋转中的UpdateModel（）只调用4次： http://www.pixdip.com/opengles/limited.php 和所需code（这应该是足够了）就在这里： http://www.pixdip.com/ opengles / code.php
Apk for translation/rotation about arbitrary points in which updateModel() is called 4 times only:http://www.pixdip.com/opengles/limited.phpand required code (which should be sufficient) is here: http://www.pixdip.com/opengles/code.php
对象（喷嘴/炮塔，体）的部分正在绕自己的中心对象（这是_playerCentre）不是中心，我会在以后修改。
Parts of object (nozzle/turret,body) are currently rotating about their own centres not the centre of object (which is _playerCentre), I will modify that later.
我试图表现出的逻辑 http://www.pixdip.com/opengles/images.php
I have tried to demonstrate logic http://www.pixdip.com/opengles/images.php
推荐答案
[求助]java的浮点错误是唯一的原因。
[SOLVED]java floating point errors were the only cause
M = T * I * T [INV]
M = T * I * T[inv]
没有导致成单位矩阵，代替使用Matrix.MultiplyMM所以
did not result into an identity matrix,so instead of using Matrix.MultiplyMM
我型矩阵之间的所有的乘法
I type all the multiplications between the matrices
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