transformation

问题 Question is simple so, no codes! If someone knows Box2D and SDL2, then, please tell me how to wrap SDL_Rect with b2body. Ofcourse, it requires to know the conversion of metre to pixel and vice versa. This is because Box2D measures distance in metres. Can you give me a simple expression or function to convert metres(of Box2D) to pixels or pixels to metres(of Box2D)? 回答1: Can you give me a simple expression or function to convert metres(of Box2D) to pixels or pixels to metres(of Box2D)?

问题 If I use a transformation function like translate / rotate on a canvas, then all points are transformed when passed to any canvas function. This works like a charm, but is there also a way to simply get the transformed point without actually drawing? This will be extremely helpful when debugging. All I can do now is looking where the point ends up, but I cannot seem to obtain the calculated transformed coordinates. So, say I rotate 90 degrees, is there any function that takes a point (i.e.

问题 Process of scaling x,y coordinates of one rectangle to other rectangle coordinates is pretty simple as better explained at this link http://www.icoachmath.com/math_dictionary/scale_factor.html if we have two rectangle one is having Maxwidth: 2000 and Maxheight: 1000 and second rectangle of size MaxWidth : 4000 and MaxHeight = 2000 so scale factor for converting coordinate of rect1 to rect2 would be for x in rect2 : (x in rect1) * (MaxWidth of Rect2/ MaxWidht of Rect1) for y in rect2 : (y in

问题 I have noticed that the half of the first pixel column of the image is not drawn after a Graphics Transform Scale on the OnPaint event. All the code needed to reproduce it is at the end of the post. Basically I've created a Class derived from PictureBox called PictureBox2 and it overrides the OnPaint method to perform the Scale transformation. It also changes the InterpolationMode to NearestNeighbor to prevent Graphics from changing the pixels look. The PictureBox control was added to a Form

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . Can anyone recommend some good starting points for understanding Transformation Matrices for dummies like me with poor math skills. I'm willing to learn the math, and I'm not a complete idiot (I hope) but the examples I'm finding seem to require a huge leap from what I know, to what I need to know. 回答1: I wrote

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . Can anyone recommend some good starting points for understanding Transformation Matrices for dummies like me with poor math skills. I'm willing to learn the math, and I'm not a complete idiot (I hope) but the examples I'm finding seem to require a huge leap from what I know, to what I need to know. 回答1: I wrote

问题 One attempted approach was to use TexturePaint and g.fillRect() to paint the image. This however requires you to create a new TexturePaint and Rectangle2D object each time you paint an image, which isn't ideal - and doesn't help anyway. When I use g.drawImage(BufferedImage,...) , the rotated images appear to be blurred/soft. I'm familiar with RenderingHints and double-buffering (which is what I'm doing, I think), I just find it difficult to believe that you can't easily and efficiently rotate

问题 I develop a simple 3D engine (Without any use of API), successfully transformed my scene into world and view space but have trouble projecting my scene (from view space) using the perspective projection matrix (OpenGL style). I'm not sure about the fov, near and far values and the scene I get is distorted. I hope if someone can direct me how to build and use the perspective projection matrix properly with example codes. Thanks in advance for any help. The matrix build: double f = 1 / Math.Tan

问题 I have this table view UserName Product NumberPurchaces -------- ------- --------------- 'John Doe' 'Chair' 4 'John Doe' 'Table' 1 'Jane Doe' 'Table' 2 'Jane Doe' 'Bed' 1 How can I create a query that will provide this pivot view in Oracle 10g ? UserName Chair Table Bed -------- ----- ----- --- John Doe 4 1 0 Jane Doe 0 2 1 Any way to do it dynamically? I saw so many approaches (decode, PL/SQL loops, unions, 11g pivot) But I've yet to find something that will work for me based on the above

问题 This is a basic transform question in PIL. I've tried at least a couple of times in the past few years to implement this correctly and it seems there is something I don't quite get about Image.transform in PIL. I want to implement a similarity transformation (or an affine transformation) where I can clearly state the limits of the image. To make sure my approach works I implemented it in Matlab. The Matlab implementation is the following: im = imread('test.jpg'); y = size(im,1); x = size(im,2