Tagged Questions

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

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1answer
290 views

libgdx rotation (animation, arrays) issues and help needed

well i am a noob at java and libgdx. i got the homing bullet working with the help of someone. now i am smashing my head as to how i can make it rotate so it faces the ball (which is the main ...
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2answers
101 views

what's wrong with my lookAt and move forward code?

so am still in the process of getting familiar with libGdx and one of the fun things i love to do is to make basics method for reusability on future projects, and for now am stacked on getting a ...
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0answers
27 views

How to rotate a trigger actor in UDK?

Working on a project and I need a trigger actor to detect a custom projectile type I've made. I would use a KActor with a TakeDamage event, but KActors despawn my projectiles. The issue is that I ...
4
votes
3answers
434 views

How to rotate a set of points on z = 0 plane in 3-D, preserving pairwise distances?

I have a set of points double n[] on the plane z = 0. And I have another set of points double[] m on the plane ax + by + cz + d = 0. Length of n is equal to length of m. Also, euclidean distance ...
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0answers
51 views

Issue with turntable rotation openGL

I am trying to implement turn table like rotation in my openGL app. In turn-table like rotation, z-axis is not supposed to roll. But in my app z-axis rolls like anything when I try to rotate the ...
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votes
1answer
116 views

Can I have a fixed-angle sprite with a non-fixed-angle CircleCollider2D?

In Unity2D, can I have a fixed-angle sprite with a non-fixed-angle CircleCollider2D? I would like to move my character using the circle physics (without fixed-angle), but display him always as if he ...
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2answers
92 views

How can I find the difference between rotations represented as angles in [0, 360]?

What is the easiest way to find the difference between two 2D rotations/directions? I want to test if one rotation is within 10° of another. I would just subtract, but there are some problems ...
1
vote
1answer
633 views

LibGdx sprite rotation vs Box2D physics rotation problem

LibGdx sprite rotation vs Box2D physics rotation problem Tearing my hair out on this one. I am an experienced software developer, but very new to LibGdx and Box2D development. I am writing a game ...
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0answers
31 views

Why the rotation matrix of X(θ1)Y(θ2)Z(θ3) can be viewed as extrinsic rotation of order ZYX and intrinsic order of XYZ?

As title, from wiki and OpenGL red book(7e) I found the expression v' = R_x * R_y * R_z * v can be viewed as Rotate vector v about local x axis, and y axis, finally z axis. Rotate vector v about ...
0
votes
1answer
74 views

Incomplete mesh using DrawIndexedPrimitives after rotating mesh

Through help on this site I was able to draw the triangles of an unrotated, nonscaled nontransformed mesh created in Blender and exported to OBJ, accurately imported through Assimp and rendered in XNA ...
1
vote
1answer
146 views

Bullets won't shoot out of barrel in top-down shooter

So I am working on a top down shoot and have been stumped on why my bullets refuse to come out of the barrel of the gun. I know about the rotation equation which is x2 = x * cos(theta) - y * ...
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0answers
127 views

Unity crashes completely when I rotate my objects [closed]

I've started my first tiny Unity project and after 20 minutes I run into a brick wall. My goal was to create a Android 2D game with falling polygons, that you have to click and they disappear. ...
3
votes
3answers
226 views

How do I disassemble a 3x3 transformation matrix into rotation and scaling matrices?

I have a transformation matrix that rotates and scales. Is there any easy way to disassemble it into the original rotation and scaling matrices? For instance: M = R * S; // I need f and h such that ...
2
votes
1answer
116 views

Unity - Quaternion - Rotate / Unrotate Error

I'm trying to unrotate a quaternion, aligning it with the axis, and then rotate it back to where it was originally. But with every iteration it seems to lose precision and just after 20 iterations the ...
1
vote
2answers
318 views

Matrix rotation wrong orientation LibGDX

I'm having a problem with matrix rotation in libgdx. I rotate it using the method matrix.rotate(Vector3 axis, float angle) but the rotation happens in the model orientation and I need it happens in ...
0
votes
1answer
89 views

Camera rotation around point, but without centering

Let's say i have the following: Point somewhere in space Camera with position and orientation (up, right, forward) I want to rotate camera around the point, but also keep this point in same place ...
2
votes
0answers
114 views

Quaternion - rotating rigidBody to particular angle over time

Using Bullet Physics. There's a rigid body that is rotated. For some delta-time I need to rotate that body to have rotation of (0, y, 0) - keep the old y value rotation but reset x and z. The ...
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0answers
80 views

How do I get a sprite's angle after collision?

I'm using Cocos2d (version 3) and I want my hero sprite to be jostled around by incoming enemy sprites. The Chipmunk-based physics work, but I need some way to track the rotation of the sprite after a ...
0
votes
0answers
84 views

rotating sprite with quaternion in scenegraph

I have been trying to set up a scenegraph in XNA, which I then use to draw sprites in the correct places. It uses matrix transformations to accomplish this. So far, I got position and scale working ...
0
votes
0answers
33 views

XNA 2D Stencil Buffer Rotation

I am currently working on a 2d game related to planets and am trying to get a stencil buffer working with rotation. I currently have a stencil buffer found from another related answer but it refuses ...
0
votes
0answers
33 views

How to find optimal perpendicular axis of rotation vector to draw arrows?

I am drawing lines on the screen. Each line has a point (x,y,z) and a direction (u,v,w). I want to draw arrow heads on these lines, like two lines that start from (x,y,z) and leave at a 15 degree ...
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0answers
73 views

GLM Rotating Combining Multiple Quaternions?

I have a camera which I want to control with my mouse. I want the mouse to control the pitch and yaw of the camera but not the roll. To avoid loss of significance, I am storing the quaternions for ...
0
votes
3answers
150 views

OpenGL: glRotatef cause performance drop while rotating -x and -y

I have made a rotating cube and I got some performance drops while using two glRotatef calls. So basically this code is giving me 80FPS: //code 1 GLrotate_x += 0.4f; GLrotate_y += 0.4f; ...
1
vote
1answer
237 views

How can I restrict the rotation of an object to a subset of axes using quaternions?

I've got a question about quaternions in my WebGL application. How can I rotate an object only around two axes? For example, how can I exclude/nullify rotation about the Y axis? The problem is that ...
1
vote
1answer
628 views

Unity objects not rotating around pivot point

Suddenly, for some reason, objects in the unity editor started rotating around their center of gravity (at least that's what I think is going on) instead of their pivot point. I tried placing the ...
2
votes
1answer
276 views

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 ...
1
vote
1answer
625 views

Movement and rotation of bodies in top down game

We are developing a 2D top down game with libgdx using the included box2d as physics engine. We don't want our bodies to accelerate but to instantly move with the wanted velocity. The bodies are ...
1
vote
1answer
122 views

libgdx get rotated sprite coords points

I would like to get the position of each edge of a sprite when he has been rotated. I have no idea how to do it, I made a image to explain it. I would like to get the X and Y position of each Red ...
1
vote
1answer
134 views

JavaScript: Rotating a canvas around its center for a 2D sidescroller

I've been making a 2D sidescrolling game using JavaScript and HTML. The game is set in space, where the player character can fly around (Up, Down, Left and Right keys) and rotate the world around him ...
1
vote
0answers
85 views

Rotating SpriteBatch clockwise [closed]

I have developed a 2D game that looks great on the Android. Now I want to make it cross-platform. For this I need to literally rotate everything when it is on desktop. I tried to do that by rotating ...
0
votes
1answer
55 views

Rotating image around a given point

Im trying to simulate shadows in a 2d RPG, So far I can make the shadows but i cant blit them properly, Im trying to rotate them according to where the "sun" is (just a position) I have looked at ...
2
votes
0answers
30 views

Xna 4 Model Rotation with inertia not working as expected with variable updates

I am trying to rotate a model with inertia damping with the keyboard. The code works great with a fixed time step but it doesn't behave the same with a variable update frequency. Update method: ...
4
votes
1answer
253 views

How do I make a cube move by rolling?

I am learning jMonkeyEngine by making some small games with it. I have a simple rectangular cube that I want the player to be able to roll around the game world. When he presses the arrow keys, the ...
6
votes
1answer
712 views

OpenGL ES object rotation around z axis

I have an object on my screen which is presented rotated and panned, But i have 2 problems regarding the z axis rotations. It's a bit tricky to explain so i uploaded 2 videos to describe each problem. ...
1
vote
1answer
194 views

Bounding Box in Monogame for mouse picking

Hello guys so I'm implementing this mouse manager to be able to pick up objects. My application uses mainly textured quads in 3d space. I'm using bounding boxes in monogame to do so, however my ...
0
votes
1answer
389 views

How do I determine the look-at vector of a free-look camera?

I'm trying to create a free-look camera with DirectX 10. I've figured out how to get the directions for forward and back and left to right. However, I don't know how to rotate the look-at vector of ...
0
votes
0answers
291 views

Andengine Rotate Wheel with fast acceleration

I have a Wheel sprite and i am rotating it using Physics RevoluteJointDef. Its rotating. But problem is how i can make wheel to start moving fast. It took the speed after sometime like real. // ...
0
votes
0answers
216 views

Spin wheel with gesture in Andengine

I want to implement Fortune wheel in Andengine. The wheel would start spinning based on the speed of a finger fling. Then it would stop slowly like real Fortune wheel. What I am able to do now is to ...
0
votes
0answers
21 views

How do I scale and rotate around different points in Libgdx? [duplicate]

I'm using a SpriteBatcher to rotate and scale a TextureRegion in libGDX. I'd like to rotate the texture around an origin outside of the region, but have the texture scaled around the region's center. ...
0
votes
1answer
65 views

How to spin an object on its own axis?

I'm trying to spin up my own 3D vector graphics engine, so I'd like to do this without an existing library. And I don't seem to be able to find the math for the correct approach in rotating an object ...
0
votes
1answer
467 views

How to get plane rotation by known normal vector

I have a FPP quaternion Camera and Plane with known normal vector. I want to find the orientation of this Plane so I can replace it to the Camera orientation to put the camera forward vector to a ...
3
votes
4answers
163 views

Calculate turn rate between xy and target xy on a moving sprite with variable speed

My First question on here so be kind... I am writing an aerodrome simulator in as2, I need to calculate a turn rate between 2 points so that the aircraft turns nicely. I have tried a few things but ...
0
votes
0answers
115 views

LWJGL Rotating is moving

I am trying to rotate my QUAD even just a little bit. I have read pages like http://www.java-gaming.org/topics/lwjgl-tutorial-series-moving-and-rotating-triangle/30679/view.html In my render() ...
1
vote
1answer
46 views

Find out which way to rotate based on current rotation and final rotation [duplicate]

I have one object that I want to rotate to a certain angle with 'smooth' rotation. I looked up on how to solve that and I came up with this: enter image description here But how do I know in what ...
1
vote
1answer
315 views

Rotating a GameObject around its center

I'm trying to rotate a GameObject that consists of several cubes around its center of gravity on an axis. When using transform.Rotate(), it rotates around its pivot point (as shown in picture 1) and ...
0
votes
1answer
97 views

Jittery Rotational Movement with Arcball implementation

I have an assignment where I need to implement arcball using Opengl (~2.0). I have it more or less implemented but I have a some problems/issues/bugs and I'm not sure whats either causing them or how ...
5
votes
3answers
336 views

How do you calculate the rotational velocity of a flying object?

When a arrow shaped object is fired it slowly adjusts it's rotation to match the direction it is moving. But what is the actual physics behind it? The question is: How many degrees does the ship ...
-1
votes
1answer
161 views

lerp z rotation towards mousepointer

I am trying to get transform.rotation.z to chase the mouse pointer at a rotation speed. But I get a very weird results and can't figure out what I am doing wrong. var mp = Input.mousePosition; ...
1
vote
0answers
41 views

Calculating Friction due to rotation from ball bounce? [duplicate]

In this question asked by codemonkey, The rotation will depend upon: upon impact, on: Initial Speed of the ball hitting the surface (magnitude of ball velocity vector) Friction co-efficient of ball ...
2
votes
0answers
52 views

How should I model rotation caused by bounce friction? [duplicate]

In my Java2D simulation, I have a disc which, when it bounces off the boundary of a 2D region, begins to rotate, as if it had gotten some spin from the wall. I'm having trouble relating the ...