A branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.

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28
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4answers
2k views

Why does my object move faster at 45 degrees than at 90 degrees?

I have objects in my game that move faster at 45 degrees then at 90 degrees. Each object has Point (x,y) position Vector2D (x,y) direction Int speed And what I do during a update is that new ...
4
votes
2answers
1k views

What is a good way to determine if a vector is between two other vectors?

I could operate with the angles, but I do not have the angles calculated yet (and would like to avoid having to do that). It would be possible to calculate and cache the local-coordinate-frame angles, ...
1
vote
1answer
326 views

How do I determine if a tile is a slope based on the tile image?

In my game, every tile is a 32x32 texture. All the slopes are a 0 - 45 degree angle. I would like to determine, at the time I load the tile, if the is sloped by examining its texture/bitmap data. How ...
6
votes
2answers
200 views

How do you calculate if a line is facing a curve?

Given the 2 points describing a line segment, and the 3 points describing a quadratic bezier curve, how do you calculate if the line is facing towards or away from the curve? The line has a fixed ...
0
votes
0answers
93 views

Drawbacks for using only quads for model geometry [duplicate]

Possible Duplicate: Why do game engines convert models to triangles compared to keeping it as four side polygon What are the main drawbacks for using "only" quads for model geometry? Does ...
3
votes
1answer
1k views

Generating spherical world from heightmapped terrain

I am using a standard heightmapped procedural terrain in my project. However, I want the terrain to appear spherical when the user zooms out. This is an attempt to simulate the appearance of a ...
14
votes
3answers
561 views

How do you calculate the nearest point on 2 curves?

Given the points of a line and a quadratic bezier curve, how do you calculate their nearest point? .... Similarly, given the points of 2 curves, how do you get the nearest point?
9
votes
2answers
307 views

How do you calculate if 2 lines are facing toward or away?

Given the 4 points describing 2 line segments, how do you calculate if line A is towards or away from line B? The 2 lines have a fixed length, and can be measured as distance from x1/y1 to x2/y2.
2
votes
2answers
1k views

How can I transform a point from world space to object space?

If I have an object space described by transformation matrix that should be applied to object to transform it to world space, what I have to do to transform point (world space) to that object space. ...
0
votes
2answers
542 views

Ways to define a curve

I'm trying to give shapes in my physics engine roundness/ curvature. I am aware of various methods for mathematically defining curves; such as bezier-cruves, ellipses, etc. However I am not sure ...
5
votes
1answer
7k views

How to calculate a 3x3 rotation matrix from 2 direction vectors?

I've got 2 direction vectors, for the X axis and the Y axis of the object. How do I calculate the rotation matrix of the object using these?
4
votes
2answers
496 views

OpenGL, Offset and Camera Space

I was reading chapter 4 of the Arcsyntesis OpenGL tutorial when I came across this line in the GLSL shader. vec4 cameraPos = position + vec4(offset.x, offset.y, 0.0, 0.0); About it, the tutorial ...
2
votes
1answer
655 views

Can Bullet Physics (or another 3d physics engine) use callbacks in my engine to check static geometry?

I'm wondering if it's possible to use or hack Bullet 3d Physics (or another free 3D physics engine) so that I don't need to "import" my static geometry into Bullet - instead I want to do it the other ...
21
votes
4answers
2k views

Is there a 3D equivalent of hex tile maps?

Probably the biggest advantage of a hex-based versus square-based map tiling is that the center of each hex has the same distance to all its neighboring hexes. Is there a similar shape that tiles this ...
7
votes
2answers
2k views

How do I align the matrix used in SpriteBatch and the matrix used in BasicEffect?

I'm writing a Windows tool that uses XNA and allows the user to place textures on the screen. I'm using a 'camera' for the SpriteBatch used to draw the textures, e.g: Matrix matrixForSpriteBatch = ...
7
votes
1answer
495 views

How can I determine the first visible tile in an isometric perspective?

I am trying to render the visible portion of a diamond-shaped isometric map. The "world" coordinate system is a 2D Cartesian system, with the coordinates increasing diagonally (in terms of the view ...
9
votes
1answer
3k views

Circle-Line Collision Detection Problem

I am currently developing a breakout clone and I have hit a roadblock in getting collision detection between a ball (circle) and a brick (convex polygon) working correctly. I am using a Circle-Line ...
11
votes
2answers
4k views

Are the Minecraft animations hardcoded into the game?

I would like to know how the animation system works in minecraft. I get a feeling that all the mobs are hardcoded into the game. Did notch really sit there and create the matrices for all the ...
10
votes
5answers
683 views

How would one determine the length of a path?

I have a game that requires each player to move along one specified path. I draw the path using Bézier curves. How can I determine the total real (not linear) length of the path and the distance that ...
5
votes
1answer
2k views

Creating similar effects of Geometry Wars in 2D only

I want to create a game with similar effects to that of "Geometry Wars"... for those who have never played the game, basically, massive amounts of 'bending' and 'warping' effects are done on the ...
6
votes
1answer
2k views

Moving a particle around an Archimedean spiral at a constant speed

I want to move a particle in a spiral at a constant speed. Note that that is not a constant angular speed. This is proving rather difficult, and I'll go through my method so far below. The spiral in ...
14
votes
3answers
7k views

How do you programmatically generate a sphere?

Could someone please explain how it would be possible to create a sphere vertices, indices and texture coordinates? There is a surprising lack of documentation on how to do so and it is something that ...
8
votes
1answer
2k views

Am I going to regret using a color based collision detection system?

I'm just getting started build my first game with XNA (I'm experienced with C# but not games). I'm building a pretty simple top down 2d shooter. I read this tutorial on using a color based collision ...
7
votes
2answers
1k views

Geometry System of Populous: The Beginning

I want to to develop a game like Populous: The Beginning with my friend. But we could not find out what type of geometry they have used for the world. We know that - all tiles have the same size - ...
2
votes
2answers
156 views

What is the purpose of glEdgeFlagv?

I know that what both glEdgeFlagv and glEdgeFlag do is toggle boundary edge status, but my question is why does the v version exist when the documentation specifies that the only difference is that ...
4
votes
3answers
886 views

scanline filling a trapezoid

I have computed the four corners of the viewable bit of 2d map in my 3d view. So I know the trapezoid that is visible, and I want to 'visit' these tiles in my map. So my algorithm is basically a ...
1
vote
1answer
839 views

Using Actionscript 3's Graphics API in Flixel

My question sounds pretty simple but awfully, I couldn't find much information on the internet. How can I draw a circle in my FlxSprite? I couldn't find much information about drawing geometric ...
1
vote
1answer
2k views

what algorithms exist for combining multiple triangle meshes into one mesh

Let's say I have a terrain mesh of some triangles, and several smaller meshes which I want to add to that terrain mesh (think ground and some small mounds or berms for example). What would I look for ...
0
votes
2answers
875 views

How to generate a rotation matrix or a quaternion (properly rotated in regards to texture coordinates) for each triangle of a mesh?

I'm trying to build a uniform grid made of 3D points over the surface of an arbitrary mesh (we have texture-coordinates for each vertex...) Or to reformulate: imagine a mesh textured with a texture ...
2
votes
1answer
1k views

How do I determine the collision normal in an axis aligned bounding box collision?

I have a 3d moving box and a stationary box. I can detect collisions ok but now I would like to slide the moving box against the stationary box as a collision response. For this I need the normal of ...
0
votes
1answer
292 views

How do I rotate a segment + normal so that the normal is (0,-1) and the segment is now axis aligned

I have an arbitrary line segment, which may or may not be axis aligned along with its normal eg: Segment(Coord(-1,-1), Coord(1,1), Coord(-1, 1).normalize) which represents a line segment with a 45 ...
3
votes
2answers
247 views

How to generate slopes that meet the plane, is using collision detection a good idea?

I have a terrain, which is defined by mesh. And there are a lot of other polygonal faces scattered throughout the terrain, they can be located above, or below or cutting through the terrain. You can ...
6
votes
2answers
585 views

Perspective in early pseudo-3d games

Please take a look at the screenshot below, from the old classic Space Harrier. My question regards the curved perspective on the chequerboard 'ground'. It's got a strangely curved geometry (I ...
4
votes
1answer
402 views

rotating an object from sourceAngle to destAngle, both 0-359, clockwise or counter clockwise?

I've got a game object i need to rotate. It's current angle is player.rotation, the destination is targetAngle, both in degress, 0 to 359. I've got a function named rotateDirection(float sourceAngle, ...
8
votes
1answer
198 views

What are some ways to implement variable body shapes?

Games like Ryzom and the Sims allow players to have human bodies with different shapes: wide or thin, tall or short, big noses or small, etc. It seems to me that it'd be impractical to pre-generate ...
1
vote
2answers
477 views

Rotating coordinate system

Lets say that you want to rotate simple cube around fixed point in center. Is it possible to use such coordinate system, that you need to use only sine and cosine in order to rotate? I have done ...
5
votes
2answers
1k views

Generating geometry when using VBO

Currently I am working on a project in which I generate geometry based on the players movement. A glorified very long trail, composed of quads. I am doing this by storing a STD::Vector, and removing ...
0
votes
3answers
301 views

exact point on a rotating sphere

I have a sphere that represents the Earth textured with real pictures. It's rotating around the x axis, and when user click down it has to show me the exact place he clicked on. For example if he ...
10
votes
2answers
11k views

How can I convert a mouse click to a ray?

I have a perspective projection. When the user clicks on the screen, I want to compute the ray between the near and far planes that projects from the mouse point, so I can do some ray intersection ...
1
vote
2answers
2k views

Voronoi regions of a (convex) polygon

I'm looking to add circle-polygon collisions to my Separating Axis Theorem collision detection. The metanet software tutorial (http://www.metanetsoftware.com/technique/tutorialA.html#section3) on ...
14
votes
2answers
4k views

How to find if circle and concave polygon intersect?

I have a polygon (sometimes convex, but often concave), and a bunch of circles with different radius. How can I find out if a circle is intersecting/overlapping with the polygon? If it makes it ...
1
vote
0answers
293 views

How can I draw a model perpendicular to a sloped surface? [duplicate]

Possible Duplicate: How do I find rotation in 3D based on a vector/normal? My models are axis-aligned. I know the normal of the surface I want to draw them on. How do I compute the ...
1
vote
1answer
273 views

Frenet frame and application

I have just been reviewing Frenet Frame math. It is an interesting geometrical issue. I know that common applications are: camera movement along a curve tube and ribbons surface Can someone ...
4
votes
3answers
1k views

Point line collision reaction

I am trying to program point line segment collision detection and reaction. I am doing this for fun and to learn. The point moves (it has a velocity, and can be controlled by the user), whilst the ...
5
votes
1answer
2k views

Morph a sphere to a cube and a cube to a sphere with GLSL

I'm getting started with GLSL with quartz composer. I have a patch with a particle system in which each particle is mapped into a sphere with a blend value. With blend=0 particles are in random ...
4
votes
1answer
3k views

How do I find rotation in 3D based on a vector/normal?

I've been playing with Blender and Python, doing basic things like accessing vertices/normals,etc. I can get the normal of each face of a mesh. I was wondering, how can I get the rotation of a face ...
7
votes
4answers
1k views

Implementing 2D CSG (for collision shapes)?

Are there any simple (or well documented) algorithms for basic CSG operations on 2D polygons? I'm looking for a way to 'add' a number of overlapping 2D collision shapes. These may be convex or ...