Java OpenGL屏幕使用gluUnProject +设计讨论进行世界转换(Java OpenGL screen to world transformation using gluUnProjec

编程入门行业动态更新时间:2024-10-23 17:36:13

Java OpenGL屏幕使用gluUnProject +设计讨论进行世界转换(Java OpenGL screen to world transformation using gluUnProject + design discussion)

我有2个问题。一个特定的问题是为什么我的代码没有按预期工作，另一个是设计问题。

1（具体问题）：我正在尝试将屏幕坐标映射到基于2D磁贴的引擎中的世界坐标（使用x / y轴，z = 0）。我已经使用了Nehe的教程端口来了解如何实现这一点，但我得到的结果并不像预期的那样。

我有一个名为MouseController的类。每当触发鼠标事件时（通过swing的MouseListener），我将MouseEvent传递给我的MouseController。

在我的GLCanvas的绘图函数中，我调用MouseController.processClick（GL）函数，以便能够将当前的gl上下文传递给processClick函数并获取模型视图，投影矩阵和视口。

当我点击屏幕上呈现的块时，返回给我的世界坐标几乎没有任何意义。首先，我希望z值为0，但是它的9（这是我的相机设置的高度），而我的x和y值总是非常接近0（偶尔会跳到1-9）轻微的动作，然后回到非常接近0的数字）。

任何人都知道为什么会出现这种情况？ processClick函数如下：

public void processClick(GL gl) { int x = e.getX(); int y = e.getY(); if(e.getButton() == MouseEvent.BUTTON1) { gl.glGetIntegerv(GL.GL_VIEWPORT, viewPort, 0); gl.glGetDoublev(GL.GL_MODELVIEW_MATRIX, mvMatrix, 0); gl.glGetDoublev(GL.GL_PROJECTION_MATRIX, prMatrix, 0); int realy = viewPort[3] - y; glu.gluUnProject((double)x, (double)realy, 0, mvMatrix, 0, prMatrix, 0, viewPort, 0, wCoord, 0); System.out.println(x + " " + y); System.out.println(x + " " + realy); System.out.println(wCoord[0] + " " + wCoord[1] + " " + wCoord[2]); } e = null; }

当我点击我在世界坐标（4,5,0）处呈现正方形的屏幕时，我从上面的函数得到的示例输出：

878 56 878 636 0.0445182388817236 0.055475957454737095 8.900000001489369

谢谢！

编辑：使用glReadPixels读取深度缓冲区并使用它作为z（返回1）得到的结果是正确的，但是太大了20倍。

编辑2：如果我将远剪裁平面设置为与摄像机高度相同的值，它似乎工作（但这不是一个合适的）。

2（设计问题）：我觉得在OpenGL画布的绘图功能中处理点击是没有意义的。我似乎要求该函数的GL能够检索gluUnProject运行所必需的矩阵。你们怎么设计这个？理想情况下，我觉得我应该能够将此运行与绘图功能完全分开。将gl对象的引用存储到MouseController中，并在MouseListener选中它时处理单击。

关于你们如何处理它的输入也将非常感激！

I've got 2 questions. One's a specific question about why my code isn't working as intended and the other is a design question.

1 (Specific Question): I'm trying to map screen coordinates to world coordinates in a 2D tile-based engine (uses the x/y axis, z = 0). I've used a Nehe's tutorial port on how to achieve this but the results I get aren't as expected.

I have a class called MouseController. Whenever a mouse event is trigger (via swing's MouseListener), I pass the MouseEvent into my MouseController.

In my GLCanvas's draw function, I call the MouseController.processClick(GL) function to be able to pass the current gl context into the processClick function and grab the modelview, projection matrices and viewport.

When I click on a block rendered on the screen, the world coordinates that are given back to me make little to no sense. For one, I would expect the z value to be 0, but its 9 (which is how high my camera is set to), and my x and y values are always really close to 0 (occasionally jumping up to 1-9 with very slight movements, then back to a number very close to 0).

Anyone have any idea why this might be the case? The processClick function is below:

Sample output I get from the above function when I click on the screen where I rendered a square at world coordinates (4,5,0):

878 56 878 636 0.0445182388817236 0.055475957454737095 8.900000001489369

Thanks!

EDIT: Reading in the depth buffer using glReadPixels and using that as the z (which returns 1) gets me results that are kind of right, but are too big by a factor of 20.

EDIT2: If I set the far clipping plane to the same value as the height of the camera, it seems to work (but this isn't really a fit).

2 (Design Question): I feel as if it doesn't make sense to process clicks in the OpenGL canvas' draw function. I seem to require the GL from that function to be able to retrieve the matrices necessary for gluUnProject to run. How would you guys design this? Ideally I feel as if I should be able to have this run completely separate of the draw function. Store a reference to the gl object into my MouseController and process the click when the MouseListener picks up on it.

Input about how you guys would/do handle it would be much appreciated too!