A branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.
3
votes
1answer
58 views
Suboptimal A* Pathfinding Solution Example using Manhattan Distance Heuristic
I believe using an overestimating heuristic with A* is not guaranteed to find the shortest path. Assuming an agent can travel as a bird using euclidean distances, the manhattan distance provides just ...
31
votes
9answers
6k views
How can I quantify a drawn line's straightness?
I'm working on a game which requires players to draw a line from a point A(x1,y1) to the other point B(x2,y2) on the screen of an Android device.
I want to find how well that drawing fits to a ...
0
votes
0answers
22 views
Outline of plane slice of arbitrary object
How would you extract the outline of a shape from slicing a plane through an arbitrary object?
Note: This is related to my Unity Answers question, but not exactly the same.
0
votes
1answer
61 views
Rotate Object Towards Direction in 2D
For my RTS game's physics engine, I'm trying to find out a clever way to make a unit face the direction it's moving in. Given a Vector2d direction of movement (its normalized velocity), how can I ...
0
votes
1answer
16 views
Maya 2015 Collada mesh transforms not applied
I am trying to load a dae (Collada) model into my 3d engine. The problem is they export the vertices and transforms seperately. So in Maya 2015 it looks like this
In the game engine I have it simply ...
2
votes
1answer
40 views
Mapping Coplanar Vertices in 3D space on to a 2D Plane
Say I have a plane specified by a normal vector and point on the plane.
I want to specify a 2-D co-ordinate system that lies 'across' the plane, and then use that to find the 2-dimensional distance ...
0
votes
2answers
57 views
Moving OBB vs. triangle intersection test
Requirements: to write a test function that, given a moving OBB (oriented bounding box) and a triangle, returns true whenever the OBB hits the triangle.
The OBB is described by its half extents (h1, ...
0
votes
0answers
25 views
Rotating between two coordinate frames
I have two coordinate frames, A and B. I want to create the rotation matrix RAB which takes you from A to B. A is a right-handed system, and B is a left-handed system. Furthermore, after moving from a ...
0
votes
1answer
77 views
Collision Detection algorithm using Line Detection
For a 2D physics sandbox I am working on, I need a way of detecting detecting a collision using lines. This sandbox uses a class called Particle, which has a x and a y (stored as a struct called ...
0
votes
1answer
64 views
How can i calculate that normal lays in same part of plane with point?
I.e. n0 for A and n1 for B. Plane divided by plane CD.
0
votes
0answers
43 views
Fat geometry shader
I've seen this video: all the geometry seems to grow and become fat. Nice effect.
I'm just approaching the shader matter, and I'm still have to learn a lot about how to change geometry via shaders. ...
0
votes
0answers
22 views
How does collision detection work? [duplicate]
I was curious on how hit collision works in games. I know there is a simple method that gives every object in a 2D or 3D world a recengular hitbox that makes it easy to detect a collision, but when ...
12
votes
6answers
2k views
What's the fastest way checking if two moving AABBs intersect?
I have two AABBs that are moving, what's the fastest way to check if they will intersect under a frame?
By moving I mean not just to check with the usual rectangle intersection method, I mean some ...
5
votes
5answers
2k views
How can I test whether points are within a polygon?
I have 2D-points, which boundaries depict a polygon. The points are at integer positions (no fractions possible).
Now I want to build an enumerator in C# that returns all points that are inside the ...
1
vote
3answers
124 views
How do I interpret the dot product of non-normalized vectors?
I know that if you take the dot-product of two normalized vectors, you get the cosine of the angle between them.
But if I take the dot-product of two non-normalized vectors (or one normalized, one ...
0
votes
0answers
38 views
How can I keep vertex order the same on every Instantiate()?
While trying to resolve another question, I have discovered that if I Instantiate() from a prefab, the order of the mesh vertices (and therefore triangles) is inconsistent between instances. This is ...
1
vote
1answer
51 views
Algorithm that cover one mesh by another mesh
Suppose I have two meshes (Let call me first MeshShirt and second - MeshBody)
Meshes are aligned (if i render both MeshShirt "covers" MeshBody). But some parts of the body are not "under" the ...
0
votes
1answer
117 views
Formula to measure uv-mapping distortion
Does anyone know a simple way of calculating (offline) the amount a texture is distorted when mapped to a triangle like the following?
Vertex Position UV Coordinates
A (Ax, Ay, Az) ...
1
vote
1answer
85 views
Chamfered cube geometry generator
I'm trying to create a geometry generator for a "Chamfered Cube". I've got the vertices working, but I'm stuck with creating the faces. I don't really know how I could re-arrange my algorithm to ...
0
votes
0answers
49 views
Calculation technique for 2D inertia tensors?
Just wondering what the techniques are out there. It's only 2D so I figured there'd be a good chance for there to be a "one size fits all" solution out there that's essentially an analytical solution.
...
0
votes
1answer
101 views
Given seams, how do I unfold a mesh?
If a user marks a seam on a mesh, how do 3D modelling programs (like Blender or Maya) unfold the mesh on to a 2D surface? I can only find papers trying to automate the seaming for you. Given ...
2
votes
1answer
141 views
Get quaternion between two objects on sphere
In a planetary gravity environment objects are represented in the following way:
struct object {
struct quaternion quat; // quaternion to represent the rotation between the object and the center ...
1
vote
1answer
121 views
How to access Maya Bonus Tools 2012 in Maya 2014
I have been trying to use the paint geometry tool for Maya 2014 but it isnt showing up. I downloaded Bonus Tools 2012 and installed it. Where can I find this tool in Maya 2014?
0
votes
1answer
231 views
How to determine the distance between a point and a rotated rectangle
This question is very similar to How do I calculate distance from a point to a rectangle?. But that question assumes that the rectangle is axis-alligned, or not rotated.
So just like in that ...
1
vote
1answer
205 views
In a TPS, how to aim bullets to the direction the camera is pointing, but make the shooting from the player?
(In C#/XNA.) I mean, I can't find an answer nowhere. I'm trying to learn how to make a Third Person Shooter, especially like the one I found in a game called "M.A.R.S.", from Epic Games. I don't want ...
2
votes
1answer
66 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 ...
0
votes
3answers
55 views
Calculating the center of a turning circle
I'm trying to understand how to calculate the midpoint of a turning circle. In the attached picture, my unit is at location U. I want to compute the trajectory of the unit as it turns toward the ...
3
votes
1answer
115 views
How can I animate characters' static-geometry eyes?
Here's a Nintendo example:
Specifically, the animation of the pupils seems not to animate the geometry.
How is this done?
0
votes
1answer
94 views
How to calculate “real” distance between cursor and away object?
I don't really know how to formulate the title, but the problem is the following:
I'm using a scripting language called "SQF" which has been created by a company named "Bohemia Interactive" (no, I do ...
1
vote
1answer
52 views
Rotating a square rendered on a Bitmap
I'm writing a Software Renderer for fun/learning. Basically, it's just a giant array of integers which contain hexadecimal values (representing colour) that are rendered to the screen....
int ...
2
votes
2answers
46 views
Calculating angle a segment forms with a ray
I am given a point C and a ray r starting there. I know the coordinates (xc, yc) of the point C and the angle theta the ray r forms with the horizontal, theta in (-pi, pi]. I am also given another ...
3
votes
2answers
341 views
How to calculate direction from initial point and another point?
I'm making a simple game where I shoot things from a certain point on screen (A).
I tap the screen and shoot the projectile from initial point(A) to the tap point(B).
But I want the projectile to ...
8
votes
3answers
744 views
How do I translate a spherical coordinate to a Cartesian one?
Could someone point me in the right direction as to how this might be achieved? 3D math / geometry often throws me.
I'm looking for something like this (ideally in C#):
public Vector3 ...
1
vote
1answer
28 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 ...
0
votes
1answer
56 views
Picking a local origin as the centroid of given three points in 3D
Given three points non-collinear P, Q, R in 3D, I need a generic method to generate x', y', z' unit vectors that behave like origin of local coordinate system.
x' and y' vectos should be on the plane ...
1
vote
1answer
72 views
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, ...
0
votes
1answer
50 views
Geometry design and buffers
I'm making some tests with rendering stuff and I'm wondering how to design my Geometry class. For the moment, here is how I do:
Init: Stock array with positions, array with colors, array with ...
1
vote
2answers
106 views
How to find the points of intersection of two OBBs
In my game I need to be able to find the points of intersection between two OBBs.
I'm using Separate Axis Theorem to check if there's an intersection and get the penetration vector if there is one.
...
0
votes
2answers
127 views
which quarter of a triangle the point is in
I've got a world made out of squares. The square are devided in four triangles like this:
The corners have their heights stored in a 2D array and the center height is the average of the corners. To ...
3
votes
1answer
375 views
Explain this line segment intersection code
I've been reading this article on pathfinding over polygon meshes using line-of-sight, and in the article are several code snippets. One of them, the one I'm trying to understand, is a simple function ...
3
votes
2answers
244 views
How to make a projectile align correctly with the entity that shot it
I'm developing a 2D game. In the game, all entities can rotate 360 degrees. Each entity holds an angle value, and every frame it is drawn rotated around it's center by it's current angle value. For ...
1
vote
1answer
91 views
XY Location scaling with varying density screens
I have a phone with resolution H=1280,W=720,Density=2
I have a tablet with resolution H=1216,W=800,Density=1.331
I drew a rectangle on my phone with corners Left,Top (-1.6,1.55), Right,Bottom ...
0
votes
0answers
45 views
Equation / formula to determine an objects position on an ellipitcal path
I'm making a space game, as such I need objects to follow an elliptical path (orbit).
I've worked out how to calculate all the important aspects of my orbits, the only remaining thing is how to have ...
1
vote
1answer
85 views
Point in Polygon, Ray Method: ending infinite line
Having a bit of trouble with point in polygon collision detection using the ray method
i.e. http://en.wikipedia.org/wiki/Point_in_polygon
My problem is I need to give an end to the infinite line ...
1
vote
1answer
75 views
Reflection velocity
I'm trying to get a moving circular object to bounce (elastically) off of an immovable circular object. Am I doing this right? (The results look right, but I hate to trust that alone, and I can't ...
8
votes
1answer
881 views
Tessellation vs Geometry Shader
Correct me if I'm wrong, but both the Geometry Shader and the Tessellation Shader jobs are to generate vertices in the Graphic Pipeline. What I would like to know is how they are different and when ...
2
votes
1answer
326 views
Sphere-Sphere intersection and Circle-Sphere intersection
I have code for circle-circle intersection. But I need to expand it to 3-D.
How do I calculate:
Radius and center of the intersection circle of two spheres
Points of the intersection of a sphere ...
3
votes
2answers
320 views
Find the next cell in a grid from a point and direction
I'm trying to solve a very simple problem but I'm unable to come-up with an efficient solution so far. What I'm really trying to do is voxelize triangles in a three dimensional environment but I'll ...
2
votes
2answers
104 views
Connecting two arbitrary points with 2 lines
DEFINITIONS:
Any "Point (x, y)" mentioned below is really the bottom left coordinates of a 1 unit by 1 unit rectangle. A "Line" is a defined as a rectangle that is either 1 unit tall and 1 unit or ...
3
votes
3answers
374 views
Throwing a ball and estimating its path using a Physics engine
The problem:
A player entity wishes to throw a ball from a known position with a known initial velocity. The surrounding environment contains physical objects that can alter the trajectory of the ...
