# Tagged Questions

Transformation in game development is usually refers to linear algebra operations on points, vectors and matrices.

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### OpenGL not rendering full scene, it is a mystery [closed]

I am trying to draw a scene in the sort of style of mock vector graphics. I've helped on a 2D game before with GLSL, but I tried to keep a simple approach to this project since I'm working by myself, ...
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### How to translate vertex buffer coordinates in 2D

I am trying to (using a 2D Directx9 engine library) rotate/translate a set of points in a vertex buffer. I understand how this would be done in a 3D system - i.e using the vertex shader stage of ...
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### Can't figure out projection transform

I'm trying to fugure out all the spaces transformations, and currently have some inconsistency I can't understand. I'm working on a 2D game (so we assuming Z is always 0 for now), on a device with ...
98 views

### Distort a quad with a World Matrix

Is it possible to distort a quad multiplying its vertices by a specific world matrix? See the picture to understand what kind of distortion I need: Please note, that the quad is in 3d space and I ...
713 views

### How do I rotate and flip 2D sprites stored in a 1D array of pixels?

I am using a 1D array of pixels for rendering in 2D in java. I am interested in rotation (in radians) and mirroring across the x and y axes. The desired result looks something like this: Public void ...
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### Camera world matrix to view matrix

I've been working on a game engine and I model every object in my scene graph as an "entity" this includes my camera. My camera therefore has a position and rotation in world space and at the moment ...
128 views

### Why does my ship look like it's going backwards instead of fowards? [closed]

I'm making an Asteroids-clone based on this tutorial. I'm stuck on the 5th part of the tutorial. For some reason my ship is going backwards instead of forward or it looks like its going forward, but ...
4k views

### Simultaneously translating and rotating sprite in Unity

I have a 2D object (a PNG file I dragged onto the screen) which is a circle I would like to move left and right when the correct side of the screen is touched and have it rotate in the respective ...
404 views

### How do I get a SphereCollider's global origin in Unity?

I've been following this tutorial: Understanding Steering Behaviors: Collision Avoidance but I'm having trouble implementing one of the functions correctly in Unity, here's the code: private ...
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### If object is bellow another object… do something [closed]

I have 2 objects in scene. When pillar is bellow target, pillar object needs to animate. I get this error: "NullReferenceException: Object reference not set to an instance of an object". var pillar : ...
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### How do I deal with floating-point error given a far-away camera?

Whenever a camera is "far" away (its location is some "large" vector), trouble arises when rendering objects close to it: It is the classic precision loss from subtracting 2 floating point numbers. I ...
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### transformation before the perspective divide but after projecting perspectively

My problem is that I would like to confine a scene render to a (possibly rotated) rectangle without using glViewport(). I don't want to use it to save, if possible, some cycles that would otherwise be ...
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### When and how to apply affine translations to vertices of a mesh with LWJGL

So, I have a rigid body class, containing a list of vertices and a 4x4 transformation matrix. At the moment, I'm applying the transformation matrix to each vertex individually, and am unable to revert ...
3k views

### Transform world space using Kinect FloorClipPlane to move origin to floor while keeping orientation

The Kinect SDK provides a property SkeletonFrame.FloorClipPlane that describes the orientation of the floor plane relative to the camera. MSDN contains slightly more information in the Coordinate ...
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### How are 2D transformation matrices applied to their targets?

I understand mathematically how transformation matrices work, in that a transformation matrix multiplied by a vector results in a new vector, and we use the matrices for rotation, translation, etc. I ...
31 views

### Error in plane transformation

I have a bunch of coplanar points, who sit on plane P. I want to translate the plane to Q with the points upon. Here is what I do: I take three points from P, say a, b, c. Their centroid is denoted ...
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### How do I combine matrix transformation with non-uniform screen scaling in Flash?

I'm using a Flash transformation matrix for affine transformation. I have a rectangular image being rotated and scaled (in 2D). There are two sets of scaling variables, ScreenScaleX and ScreenScaleY, ...
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### Matrix transformation

I have to find components of a matrix for 3D transformation. I have a first system in which transformations are made by multiplying: M1 = Scale x Rotation x Translation. I want to have the same ...
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### How can I transform a Point2f with a matrix on Android?

I'm developing for Android and I'm using the android.renderscript.Matrix3f class to do some calculations. What I need to do now is to now is to do something like mat.tranform(pointIn, pointOut); So ...
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### Do I need to store a generic rotation point/radius for rotating around a point other than the origin for object transforms?

I'm having trouble implementing a non-origin point rotation. I have a class Transform that stores each component separately in three 3D vectors for position, scale, and rotation. This is fine for ...
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### GLSL Normals not transforming propertly

I've been stuck on this problem for two days. I've read many articles about transforming normals, but I'm just totaly stuck. I understand choping off W component for "turning off" translation, and ...
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### How do I rotate a sprite with ccbezierTo in cocos2d-x?

In cocos2d-x, I move a sprite with ccbezierTo like this: // use for ccbezierTo bezier.controlPoint_1 = ccp(m_fish->getPositionX() + 200, visibleSize.height/2 + 300); bezier.controlPoint_2 = ccp(...
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### Zooming in isometric engine using XNA

I´m currently working on an isometric game engine and right now I´m looking for help concerning my zoom function. On my tilemap there are several objects, some of them are selectable. When a house (...
748 views

### How to project spherical coordinates to canvas

I have objects with coordinates in a spherical coordinate system (altitude alt and azmiuth az). I want to project those to my canvas with a given size (128 x 128 pixels²) and resolution (about 6 px/°)....
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### How can I transform one triangle into another triangle with HTML5 Canvas? [duplicate]

Given a triangle I'm searching for the canvas transformation to transform it into an other Triangle with the corner coordinates (A,B,C) Input triangle: Red Triangle: A'=(0,0) B'=(80,80) C'=(0,80) ...
977 views

### How can I make EaselJS' skew behave like canvas'?

The skew property of a bitmap in EaselJS (given as angle) rotates the image such that it also flattens. I'd like to skew it without "squashing" it, as canvas does. JSFiddles, to demonstrate: Canvas ...
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### What are the performance and size tradeoffs of Eigen::Transform versus Eigen::Matrix4f?

We finished migrating from DirectXMath to the Eigen math libraries for our 3D-Game Engine last week for portability reasons. After implementing transformations with matrices as we know them, we found ...
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### How do I animate Unity GUIComponents?

I want to transform my GUIWindow from the bottom of the screen to the middle whenever the user presses a button. How can I do this?
2k views

### Generating transformation matrix for 2D camera with pan/zoom/rotate

Question How do you implement a camera with pan/zoom/rotation for a 2d game? Is it acceptable to multiply together a series of transformation matrixes to generate a final transformation matrix that ...
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### How to rotate vertices of 2D shape using a transform matrix?

I am making a top-down 2D game and am currently working on implementing improved collision using SAT. I programmed a Shape class with a Vector2 center that is its position in world space. On top of ...
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### How can I make an attached gameobject behave correctly on character flip?

I have a character that on start-up is equipped with another gameobject/prefab as a weapon, attaching it to a hand. void Start() { handFront = transform.Find ("root/Hip/BodyBone/OverArmFrontBone/...
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### How to translate swipe gestures into rotations?

I am making a snake game. I want to rotate my snake in the direction specified by swiping on the screen, the directions are limited to orthogonals (90 degree increments). It's an android game. Can ...
25k views

### How can I translate a game object towards a position?

I am instantiating my game objects (spheres) through scripts. I want my spheres to move from one location to another. but I don't know how to do this. Update is called once per frame. Is that what I ...
2k views

### (unity) move the world or the character

I'm making a game like this: https://www.youtube.com/watch?v=hO7573lphqI wherein a 3D ship is flying around on a 2D plane. From the player's perspective, the ship will stay stationary in the center ...
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### How can I determine the pixels covered by a transformed triangle (without drawing it)?

I have three points that form a triangle in a 3D scene. I want to apply an arbitrary rotation/translation transformation to this polygon and later check in which pixels of an image they would be ...
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### Rasterizing euclidean planes

I'd like to visualize a BSP tree. To do this, I need to project an arbitrary euclidean plane onto a projection plane. I was thinking about calculating the intersections of the plane with the viewing ...
16k views

### How do I make a background fill the whole screen in Libgdx?

I'm using this code to set a 800x420 image to be full screen: public void show() { float w = Gdx.graphics.getWidth(); float h = Gdx.graphics.getHeight(); camera = new OrthographicCamera(1,...
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### Build unity like Transform class [closed]

I am building a Unity-like Transform class. This is my header file: #include "Common.h" struct Transform { public: Transform(); void Translate(float x, float y, float z); ...
285 views

### How can I GL_SELECT from a gluPerspective-transformed scene?

I'm using JOGL to access OpenGL-methods on an old OpenGL version, because of school. I have written a method which is called before any objects are drawn. This method shows which object is picked. ...
984 views

### DirectX11: Drawing multiple objects

How can I draw many different objects on screen at once, with multiple vertex buffers, using DrawIndexed()? (Drawing the same object is simple, and I'm not looking to instance) ...but I am looking ...
629 views

### How can I properly rotate a 2D vector in the “flipped” XNA client space?

In my 2d XNA game, because SpriteBatch treats world space as client space and has positive Y axis down and negative up, I've built my game's world space with that coordinate system too. However, I've ...
9k views

### How can I stop transform.position from being modified when adding a child object?

I suspect there is a well-known and easy to explain reason for the behavior I'm seeing, but I am having difficulty explaining it (and likely not able to Google for the answer). When adding a child ...
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### Why translation uses multiplication and not addition? [closed]

To translate an object from (x, y, z) to (a + x, b + y, c + z) it's done using: OK, that's cool, but why would we multiply in the first place when we can add the two matrices directly as: ...
320 views

### Keep Mini map static after rotating / zooming with camera

Hi I am making a 2D game, where the Camera is able to rotate / zoom in or out on the camera focus (the player usually). However my game also contains a mini-map, and so far whenever I have to rotate ...
321 views

### Are there multiple valid definitions for what translate, rotate and scale do?

Are there multiple valid definitions for what translate, rotate and scale do to the 4x4 matrix? I bring up this question, because I have a simple webgl program that draws a square and does a few ...
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### How to make child transforms honor parent origin

I'm working on a 2D transform system that has the following requirements: Transforms can have children Transforms have anchor points/origins that offset them Children should honor the parent's ...
3k views

### Unity3D Drag Object with Mouse Gives Invalid Position

I am trying to implement a simple script to drag a GameObject with the mouse in Unity. However, when the position of the object is updated with the following script, I get an error saying: transform....
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### Displaying normals of a geometry

I have a rectangle which is created by 2 triangles and it is in x-z plane, and i have object on it. Now, the normals of two triangles (face normals) are y axis i.e. (0,1,0). I want to display normals ...