Tagged Questions

Rotation is the circular movement of an object around a specific axis.

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11
votes
2answers
2k views

Arbitrary Rotation about a Sphere

I'm coding a mechanic which allows a user to move around the surface of a sphere. The position on the sphere is currently stored as theta and phi, where theta is the angle between the z-axis and the ...
3
votes
1answer
1k views

Convert rotation from Right handed System to left handed

I have Euler angles from a right handed system that I am trying to convert to a left handed system. All the information that I have read online says that to convert it simply multiply the axis and ...
3
votes
2answers
458 views

3D rotation matrices deform object while rotating

I'm writing a small 3D renderer (using an orthographic projection right now). I've run into some trouble with my 3D rotation matrices. They seem to squeeze my 3D object (a box primitive) at certain ...
5
votes
1answer
3k views

How do I rotate a sprite so that it is 'pointing' in the direction it is moving?

I have a sprite, e.g a missile, heading in a certain direction (using a velocity vector). How do I figure out its how much to rotate it so that it gets drawn 'pointing' in the direction it is ...
1
vote
0answers
191 views

Camera not staying behind model while moving in circle

I have a camera behind a model (3rd Person) and I'm having problems KEEPING it behind the model. When I first start my game, you see the back of the model. If the model moves forward, backward or ...
1
vote
1answer
152 views

Camera wont stay behind model after pitch, then rotation

I have a camera position behind a model. Currently, if I push the left thumbstick making my model move forward, backward, or strafe, the camera stays with the model. If I push the right thumbstick ...
7
votes
2answers
635 views

Rotate a vector

I want my first-person camera to smoothly change its viewing direction from direction d1 to direction d2. The latter direction is indicated by a target position t2. So far I have implemented a ...
4
votes
2answers
1k views

XNA 2D Rotated Rectangle Collision Response

I am using Rotated Rectangles which collide using the Separating Axis Theorem and they work perfectly fine for collision detection using Intersects and Contains. However, I am starting to use faster ...
0
votes
1answer
2k views

rotate sprite and shooting bullets from the end of a cannon [duplicate]

Possible Duplicate: How to Align Gun with Bullets Hi all i have a problem in my Andengine code, I need , when I touch the screen, shoot a bullet from the cannon (in the same direction of ...
2
votes
2answers
1k views

Rotating a child shape relative to its parent's orientation

When rotating a shape using a quaternion value I also wish rotate its child shape. The parent and child shapes both start with different orientations but their relative orientations should always be ...
2
votes
3answers
579 views

OpenGL Get Rotated X and Y of quad

I am developing a game in 2D using LWJGL library. So far I have a rotating box. I have done basic Rectangle collision, but it doesn't work for rotated rectangles. Does OpenGL have a function that ...
1
vote
1answer
4k views

Rotate to a set degree then stop Unity [closed]

I'm trying to make an object rotate up on the Y axis 90 degrees, then stop. I've got the rotating up bit working fine, it's getting it to stop once it hits 90. Some of the things I've tried include ...
1
vote
1answer
479 views

How to I get a rotated sprite to move left or right?

Using Java/Slick 2D, I'm using the mouse to rotate a sprite on the screen and the directional keys (in this case, WASD) to move the spite. Forwards and backwards is easy, just position += ...
1
vote
1answer
877 views

Rotate triangle so that its tip points in the direction of the point on the screen that we last touched

OpenGL ES - Android. Hello all, I am unable to rotate the triangle accordingly in such a way that its tip always points to my finger. What i did : Constructed a triangle in by GL.GL_TRIANGLES. Added ...
0
votes
2answers
593 views

Can't get sprite to rotate correctly? [closed]

I'm attempting to play with graphics using Java/Slick 2d. I'm trying to get my sprite to rotate to wherever the mouse is on the screen and then move accordingly. I figured the best way to do this was ...
8
votes
4answers
273 views

Keeping rotation between two objects

In my XNA game I have two objects that collide. When the first object collides with the other it is able to latch on to it and move it about the world. I am having a problem with the math here (Math ...
4
votes
2answers
6k views

How can I move a sprite in the direction it is facing?

I'm using Java/Slick 2D. I'm trying to use the mouse to rotate the sprite and the arrow keys to move the sprite. I can get the sprite to rotate no problem, but I cannot get it to move in the direction ...
1
vote
1answer
509 views

Pitch camera around model

Currently, my camera rotates with my model's Y-Axis (yaw) perfectly. What I'm having trouble with is rotating the X-Axis (pitch) along with it. I've tried the same method for cameraYaw() in the form ...
0
votes
1answer
355 views

(Quaternion based) Trouble moving foward based on model rotation

Using quaternions, I'm having trouble moving my model in its facing direction. Currently the model moves can move in all cardinal directions with no problems. The problem comes when I rotate the move ...
6
votes
1answer
303 views

How can I get a 2D texture to rotate like a compass in XNA?

I'm working on a small maze puzzle game and I'm trying to add a compass to make it somewhat easier for the player to find their way around the maze. The problem is: I'm using XNA's draw method to ...
2
votes
2answers
4k views

Rotate sphere in Javascript / three.js while moving along x/z plane

I have a sphere/ball in three.js which I want to "roll" around on the x/z plane. For the z axis I could simply do this no matter what the current x and y rotation is: sphere.roll_z = ...
6
votes
3answers
2k views

How do I make an entity move in a direction?

I have an Entity instance which is updated every game tick. Let's just assume that entity moves forward constantly. I'd like to be able to give the entity's angle to a function that makes it move in ...
9
votes
1answer
1k views

Xbox thumbstick used to rotate sprite, basic formula makes it “stick” or feel “sticky” at 90 degree intervals! How do you get smooth rotation?

I am using a very basic formula to calculate what angle my sprite (spaceship for example) should be facing based on the Xbox controller thumbstick i.e. you use the thumbstick to rotate the ship. In ...
0
votes
1answer
193 views

Move model forward base on model orientation

My model rotates on it's own Y-axis regardless of where it is in the world. Here are the controls for the left ThumbStick: UP (move model forward on Z-Axis) DOWN (move model backward on Z-Axis) LEFT ...
0
votes
1answer
588 views

rotating model around own Y-axis XNA

I'm have trouble with my model rotating around it's own Y-axis. The model is a person. When I test my world, the model is loaded at a position of 0, 0, 0. When I rotate my model from there, the ...
3
votes
2answers
549 views

How to derive euler angles from matrix or quaternion?

Currently working on steering behavior for my AI and just hit a little mathematical bump. I'm in the process of writing an align function, which basically tries to match the agent's orientation with ...
8
votes
2answers
357 views

Render 3d object to 2d surface (embedded system)

i am working on an embedded system of a sort, and in some free time i would like to test its drawing capabilities. System in question is ARM Cortex M3 microcontroller attached to EasyMX Stellaris ...
6
votes
2answers
2k views

How to implement friction in a physics engine based on “Advanced Character Physics”

I have implemented a physics engine based on the concepts in the classic text Advanced Character Physics by Thomas Jakobsen. Friction is only discussed very briefly in the article and Jakobsen himself ...
1
vote
1answer
877 views

Scene graph in Unity3D

I was wondering if any scene graph-like mechanism is implemented into Unity3D? For example if I have a GameObject, can I add child cubes to it so when I rotate the parent GameObject, the siblings will ...
1
vote
0answers
245 views

Getting and Setting Rotation in XNA around the Center of my Model with XNA

Alright, so I'm currently debating how I want to do this. Basically this is what I'm trying to accomplish. I've created a system to allow me to make my environment a little bit easier. I'm ...
2
votes
2answers
2k views

Rotation matrix derived from quaternion is opposite of expected direction

When I calculate a rotation matrix from a quaternion, it seems to be in the opposite direction. For instance: For a rotation of +45 degrees about the Y-axis, I would expect to get the following ...
1
vote
1answer
2k views

Vector movement in space type game (Mouse rotation)

I'm having an issue with my movement in my 'game' prototype. It's basically not working and admittedly my knowledge with vectors is lacking. The issue I'm running into is that the ship won't move in ...
3
votes
1answer
934 views

Rotating To Face a Point

I am trying to rotate a line to point to the mouse's world coordinates (rather where the mouse lies on the plane where y=0). I am running into a couple of problems though: Whilst it follows the ...
4
votes
3answers
1k views

How to Align Gun with Bullets

I have a top-down 2D shooter. I have an image of a player holding a gun, that rotates to face the mouse. Please note that the gun isn't a separate image tethered to the player, but rather part of the ...
1
vote
3answers
338 views

Inverting matrix then decomposing gives different quaternion than decomposing then inverting the quat

I'm getting different signs when I convert a matrix to quaternion and invert that, versus when I invert a matrix and then get the quaternion from it: Quaternion a = Quaternion.Invert(getRotation(m)); ...
1
vote
2answers
252 views

How can I determine the direction of turn?

I want a function that gives me the turn direction for my object (1 or -1) I have two angles 1 - current rotation(A) 0 <= A <= 360 2 - target rotation(B) 0 <= B <= 360 int turnSide ...
2
votes
1answer
442 views

Finding a suitable axis-angle to avoid gimbal lock

In OpenGL the camera faces the -z axis with the +y axis pointing up. I am using quaternions to represent the orientation of my objects (which works well) and am trying to do the same for the camera. I ...
5
votes
1answer
5k views

Angle between two points

I have a character who walks to random points in my room in Unity. The problem is he always faces one direction, I want to write in C# a piece of code that will get the direction the character is ...
0
votes
1answer
469 views

Character rotating around target

I'm using xaitment plugin for Unity as the AI for a demo level but I have a problem. My character is supposed to walk to random points but while it's walking there it's rotating around the point. I ...
2
votes
1answer
711 views

XNA and Draw rotation

From Wikipedia the (image) conversion degrees / radians shows the quadrants so that the increase of radians causes a counter-clockwise rotation but when using the following code the sprite is rotated ...
0
votes
1answer
412 views

Joystick example problem for android 2D

I've searched all over the web for an answer to this, and there are simular topics but nothing works for me, and I have no Idea why. I just want to move my sprite using a joystick, since I'm useless ...
0
votes
2answers
976 views

XNA - positioning after rotation

I have a turret with a 2 gunbarrels. The turret rotates towards my mouse. So far no problem. When it creates a few bullets and positions them at the end of the gun barrels. Here is the problem. It ...
3
votes
1answer
453 views

Smoothing rotation

I've spent the last three days trying to work out how to rotate a sprite smoothly depending on the velocity.x value of the sprite. I'm using this: float Proportion = 9.5; float maxDiff = 200; float ...
0
votes
1answer
220 views

Rotation based on x coordinate and x velocity?

-(void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { float deceleration = 0.3f, sensitivity = 8.0f, maxVelocity = 150; // adjust velocity based on ...
6
votes
3answers
951 views

Tetris : Effective rotation

I rotate each piece by rotation formula. More detail, because rotation angle is 90 so : xNew = y; yNew = -x; But my method has met two problems : 1) Out of box : each type of pieces is fit in ...
7
votes
3answers
2k views

How to keep my Quaternion-using FPS camera from tilting and messing up?

I am using an FPS-like camera, and it uses quaternions. But, whenever I try looking up and then sideways, it tilts, and sometimes it can turn upside down. How can I fix this?
0
votes
3answers
604 views

Rotating Sprite around Y-Axis (2D)

I'm going to be creating a game soon, and part of it involves spinning sprites. The sprites will be spinning around the Y-Axis (imagine a spinning plate on top of a stick, where the stick stands up ...
7
votes
1answer
667 views

How To Approach 360 Degree Snake

I've recently gotten into XNA and must say I love it. As sort of a hello world game I decided to create the classic game "Snake". The 90 degree version was very simple and easy to implement. But as I ...
1
vote
1answer
287 views

rotating an object on an arc

I am trying to get a turret to rotate on a 90 degree arc (rotating about 2 orientations about the y-axis), and have hit a wall. I have 8 possible starting orientations (multiples of 45 degrees about ...
0
votes
2answers
1k views

Rotate object Up/Down/Left/Right in any orientation

I'm rendering model at the origin with a fixed camera looking at it positioned on the z axis. I want to be able to rotate the model up/down and left/right. Currently I have 2 variables, ...