Tagged Questions
3
votes
1answer
93 views
Matrix represents same rotation with different euler angles
I have Transform component storing it's rotation as Quaternion.
Transform has set/getEulerAngles (rotation order oy, ox, oz).
I want to rotate object in any direction but while testing I get ...
0
votes
1answer
53 views
Need help with a complex 3d scene (using Ogre and bullet)
In my setup there is a box with a hole on one side, and a freely movable "stick" (or bar, tube). This stick can be inserted/moved through the hole into the box. This hole is exactly as wide as the ...
2
votes
1answer
109 views
Negative scale in Matrix 4x4
After some rotations and to from quaternion conversions I get negative scale from Matrix 4x4, is it possible? I need that scale to draw sprite on screen so I get sprite flipped,
how to deal with this ...
1
vote
1answer
67 views
A controlled trapezoid transformation with perspective projecton
I'm trying to implement a controlled trapezoid transformation in Adobe Flash's ActionScript using the built-in perspective projection facility. To give you an idea of how the effect looks like:
...
1
vote
2answers
108 views
Accumulating rotations for camera
It seems there are three ways to store a camera's rotation: in angles, view matrix or quaternion. I was using euler angles since when I used a matrix it had a tendency to accumulate rounding errors ...
2
votes
1answer
178 views
Get intersected volume of two planes in 3D
I'm working on AABB - AABB collision response and I'm having trouble figuring one part out. My situation is as follows (see image).
I have a player AABB (blue) and an object which collides (brown). ...
1
vote
1answer
93 views
Movement constrained to the faces of a cube
The basic setup I'm working with is a cube rendered in-Engine (Panda3d, although I only am looking for a generalized solution) as well as a 2d square on one face of the cube. The eventual outcome I'm ...
5
votes
2answers
146 views
Plotting entities on a radar
I'm trying to build a radar system like the one in the original X-Wing games. The way it works is that there are two circular radar systems, one for behind the ship, and one for infront.
So, I've ...
5
votes
1answer
378 views
3D isometric depth sorting
How is it possible to depth sort tiles and objects in an isometric environments without any limitations? I've been researching this for a while now and there seems to be no publicly available answers ...
3
votes
2answers
188 views
How does a point squared equal the radius squared?
I am working on a simple ray tracer but I don't understand some of the formulas.
One that is bugging me at the moment is this:
If a sphere is centred at origin, a point p lies on a sphere of ...
2
votes
0answers
162 views
Catmull Rom Spline - Constant Speed
Given the equations found in the answer here:
Determine arc-length of a Catmull-Rom spline
How would one A) Apply this to a 3D Catmull-Rom Spline, and B) write A out programmatically (for the math ...
-1
votes
2answers
171 views
What kind of math should I be expecting in advanced programming? [duplicate]
Possible Duplicate:
What math should all game programmers know?
And I don't mean just space shooters and such, because in non-3D environments it's obvious that not much beyond elementary ...
0
votes
1answer
162 views
Normalizing the direction to check if able to move
i have a a room with 4 walls along the x and z axis respectively. My player who is in first person (therefore the camera) should have collision detection with these walls. I'm relatively new to this ...
2
votes
0answers
135 views
Portal View/Projection Matrix near plane
For RenderToTexture/Camera based portal rendering, the basics seems simple enough.
However, with a free camera, most of the time it is going to be looking at such portals at an angle:
Now a ...
0
votes
1answer
68 views
Vector transform equation explanation
I'm trying to understand the maths of moving points in a 3d space by making a game written in C#.
I'm looking at this wolfire blog series which explains some basic 3d maths. I've read the first two ...
1
vote
2answers
97 views
How do I apply a force using the object direction and speed?
I have a 3D object moving and I need to be able to apply forces to it such as gravity. In 2D, I would simply store its movement in dx and dy, but since this is in 3D, I am using a Vector3D direction ...
3
votes
2answers
294 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 ...
3
votes
3answers
134 views
Determining a point that reached another point
I have two points, one is moving and one is stationary. I would like to know if the moving point has reached that point or not. I tried to calculate the distance between two vectors and the distance ...
2
votes
2answers
239 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
2answers
1k 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 = ...
3
votes
2answers
205 views
Rotating voxels in 3d space amongst the x axis
I have a very simple voxel engine and so far it works based on coordinates, e.g. x, y, z. I was wondering if there is a formula for rotating groups of voxels/coordinates from the x axis(e.g. [0, 1, ...
8
votes
2answers
291 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 ...
5
votes
2answers
378 views
How to render metaballs?
How to render metaballs?
I am a Python programmer familiar with the Panda3d and Blender3d APIs. My math kinda sucks, but I know enough to write game logic code and procedural model generation code, ...
1
vote
1answer
881 views
global transform to local transform?
If an object is attached to another one and you need to set its position, rotation and scale in global space, what do you do to get the local versions of these values, knowing the same values for the ...
0
votes
1answer
182 views
Optimizing hierarchical transform
I'm transforming objects in 3D space by transforming each vector with the object's 4x4 transform matrix. In order to achieve hierarchical transform, I transform the child by its own matrix, and then ...
3
votes
1answer
291 views
Finding closest object to a location within a specific perpendicular distance to direction vector
I have a location and a direction vector indicating facing, I want to find the closest object to that location that is within some tolerance distance (perpendicular distance) to the ray formed by the ...
0
votes
3answers
403 views
Checking for collisions on a 3D heightmap
I have a 3D heightmap drawn using OpenGL (which isn't important). It's represented by a 2D array of height data. To draw this I go through the array using each point as a vertex. Three vertices are ...
0
votes
1answer
746 views
as3 3D camera lookat
I'm making a 3D camera scene in Flash, draw using drawTriangles() and rotated and translated using a Matrix3D. I've got the camera to look after a specific point, but only on the Y-axis, using the x ...
2
votes
1answer
433 views
When to use Euler vs Axis angles vs Quaternions?
I understand the theory behind each but I was wondering if people could share their experiences in when one would use one over the other
For instance, if you were implementing a chase camera, a ...
-1
votes
1answer
150 views
Camera not working
I made a camera in DX9. To move forward I press the Up arrow. To rotate on the Y axis I use the mouse. When I perform these movements on their own the camera moves at the speed I want.
However, if I ...
2
votes
2answers
144 views
Get all triangles that are < N dist from you?
Does anyone know of a way I could add a radius to this code for p? Like basically saying "this is true if the triangle is < N dist from the point"
public boolean isPointInTriangle( Vector3f p, ...
2
votes
1answer
214 views
Transform 3D vectors between coordinate systems
I've got 6 points in 3D space: A,B,C,D,E,F, that represent 4 vectors. AB is perpendicular to AC and DE is perpendicular to DF.
I need to find a transformation matrix M, that transforms AB to DE and ...
0
votes
0answers
125 views
way to do if(x > x2) x = x2 with rotation?
Alright, so I got this walking code, and some collision detection, now the collision detection returns a Vector3f of the closest point on the triangle that the projected position is at (pos + move), ...
2
votes
1answer
389 views
Is it possible to billboard a sprite using a transformation matrix?
None of the current topics on billboarding seemed to answer this question.
But, given
a sprite (or quad) that has it's own 4x4 transformation matrix
a camera with a view matrix (a standard 4x4 ...
2
votes
2answers
584 views
How to rotate an object so it stands correctly (back always facing the camera)
I have the following scene:
And I have two 3D vectors, the camera position, and the focus position. The focus vector is always behind the monster. I know how to rotate the camera around the focus ...
1
vote
3answers
375 views
Missing z-axis rotation for transforming between two vectors
I'm trying to rotate a cube so that it's facing up, but am getting hung up on the final implementation details. It now reliably will rotate the x,y axis to the correct side, but the z-axis is never ...
0
votes
2answers
294 views
Collision, then what?
I know how to check collision for example 2 spheres. But my question is how do I use the collsion response in a good way?
How do I make my character unable to walk in to the Sphere? I've got to the ...
1
vote
2answers
444 views
Rotate 3D cube so nearest side is facing user
How do I figure out the new angle and rotation vectors for the most visible side of the cube?
Why: The user can rotate cube, but when finished I'd like the cube to snap to a side facing the user.
...
0
votes
2answers
605 views
3D: First Person Movement
I've searched and searched for a solution today but haven't found one.
I have a Camera with Vector3 and also the camera has an angle.
If I use this:
hero.position.x += speedX;
hero.position.z += ...
0
votes
1answer
128 views
Directional and orientation problem
I have drawn 5 tentacles which are shown in red. I have drew those tentacles on a 2D Circle, and positioned them on 5 vertices of the that circle. BTW, The circle is never be drawn, I have used it to ...
-1
votes
1answer
266 views
Rotating points on a circle
I have drawn a 2D circle in X,Y,Z. I wanted to draw something on specific vertices of that circle and I managed to do it. When I wanted to move the circle, I wanted the vertices to get the updated ...
5
votes
1answer
1k views
How do I calculate the normal of a plane defined using homogeneous coordinates?
I can define a plane in 3D space using three 3D points (p0, p1, p2) that all lie in the plane and that form a non-degenerate triangle. Calculating the normal of the plane is as simple as calculating ...
5
votes
3answers
617 views
Arbitrary projection matrix from 6 arbitrary frustum planes
A projection matrix represent a tranformation from the camera view space to the rendering system clip space. In other words, it defines the transormation between a 6-sided frustum to the clip cube.
...
2
votes
2answers
542 views
How to interpolate a height-map with normals
My Task
I want to interpolate a heightmap by using the normal of each nearby point of the heightmap which is calculated before. When having 4 Points before i gonna have 9 points after it. ( See this ...
4
votes
2answers
302 views
Box-box contact information
I have two colliding boxes, How i can calculate contact information like (contact normal, contact point and penetration) .
Is there any simple algorithm .
Note: i'm using XNA .
5
votes
3answers
651 views
What's a pre-multiplied 4x4 matrix?
I'm using a 3d game engine, that uses a 4x4 matrix to modify the camera projection.
The matrix is in the regular 4x4 format:
r r r x
r r r y
r r r z
- - - zoom
The description for the ...
3
votes
3answers
3k views
How to get translation from view matrix
How can I retrieve the camera's world-space position from its view matrix?
The only answers I've seen to this question suggest the translation is in the last row/col but this wouldn't work since the ...
0
votes
2answers
420 views
Moving along a flat plane with accordance to camera view
I'm making a 3D game, and I'm stuck on a little experiment.
I currently have a flat plane with a free camera running around, and a sphere (really, a light approximated as a sphere) that rests above ...
3
votes
1answer
259 views
How do you triangulate a 3D point from a pair of stereo images?
I'm working with a stereo pair of photos, and trying to obtain a set of 3D points from matching points on these 2 images. How exactly is the point triangulated? Do you throw a ray from the camera ...
2
votes
2answers
616 views
Converting from different handedness coordinate systems
I am currently porting a demo from XNA to DirectX which, as I understand it, both have coordinate systems with different handednesses.
What are the things I need to bare in mind when converting ...
