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

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11
votes
3answers
599 views

Are the first three values that describe a 3D plane actually a 3D vector?

A 3d plane is typically defined as a,b,c,d. Are a,b,c actually the x,y,z coordinates of a 3d vector, with d defining the rotation of the plane, something like axis-angle rotation data?
2
votes
1answer
115 views

map the section of a procedurally generated surface on a plane

I'll try to be as clearer as I can. I have a surface on a 3D space which is not flat, it has hills and depths. My goal would be intersect it with a plane so that I can map the section of the surface ...
2
votes
1answer
117 views

How do I compute the point of a triangle-ray intersection?

I have a line (the direction vector of the player) and a triangle representing the face of a model (so composed of 3 points). I can't find the mathematical operation to check if that vector is ...
2
votes
1answer
443 views

2d grappling hook for platformer?

What are the options and mechanics for creating a grappling hook in a 2D game? In the prototype for this feature, the person runs around in a platformer world and can throw the hook at any wall, ...
1
vote
2answers
101 views

How can I compute the movement of an object along a parabola?

I am working on a simple 2D game. In the game, I have a 'robot' that throws a ball towards another robot, in the shape of a parabola. Both 'robots' have the same Y coordinate. The program knows the ...
0
votes
1answer
67 views

How to modify normal vectors with a tranformation matrix

Transformation is quite simple when it comes to Position or Color of the vertex, for Position just multiply matrix * vector and for color just don't do anything, but my question now is: How to handle ...
2
votes
1answer
474 views

Decomposing a concave mesh into a set of convex meshes

I'd like to be able to decompose a concave mesh into a set of convex meshes for 2 reasons: Transparent rendering Physics shapes Is there an algorithm that takes a set of triangles (concave) as ...
-1
votes
2answers
158 views

Using Geometric Slerp to move Camera

I'm writing a program in C++ using OpenGL and GLM; I'm trying to get my camera to follow my car. So far it successfully follows it around the screen, but I'm having trouble adjusting the Camera's ...
4
votes
3answers
2k views

How can I draw a quad in wireframe with modern OpenGL, without rendering the interior bisecting edge?

I want to draw a quad (not two triangles). I actually know that triangles are faster, as I answered this question. But let's say I am building a 3D modeling tool. It makes sense to draw a quad for ...
0
votes
3answers
3k views

Spherical coordinate from cartesian coordinate

I am implementing a type for Ogre 3D rendering engine to provide spherical coordinates. So far everything is working fine, until I try to build spherical coordinates from a cartesian vector. Here is ...
4
votes
2answers
424 views

Allowing a player to walk up and down slopes without resistance

I am trying to implement a platformer where both the player and the level are made up of arbitary polygons. One requirement is that the player can stand still on slopes, and walk up and down them ...
7
votes
2answers
800 views

How does Unity3D lower an imported .obj vertex count?

I have a question regarding how Unity3D handles importing of .obj files. I'm importing this teapot: http://groups.csail.mit.edu/graphics/classes/6.837/F03/models/teapot.obj The number of vertices ...
1
vote
1answer
296 views

How to generate AABB, OBB & Sphere from polygon soup

How can I generate AABB, OOBB and Sphere from a polygon soup, where the bounding volumes are defined as follows: AABB should be specified by min(x,y,z) max(x,y,z) OOBB should be specified by ...
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
1answer
111 views

“Walking” along a rotating surface in LimeJS

I'm trying to have a character walk along a plank (a long, thin rectangle) that works like a seesaw, being rotated around a central point by box2d physics (falling objects). I want the left and right ...
1
vote
1answer
88 views

How can I find a position between 4 vertices in a fragment shader?

I'm creating a shader with SharpDX (DirectX11 in C#) that takes a segment (2 points) from the output of a Vertex Shader and then passes them to a Geometry Shader, which converts this line into a ...
4
votes
2answers
319 views

a flexible data structure for geometries

What data structure would you use to represent meshes that are to be altered (e.g. adding or removing new faces, vertices and edges), and that have to be "studied" in different ways (e.g. finding all ...
2
votes
1answer
161 views

Why is there high performance hit with many meshes?

I am currently reading upon Geometry Instancing, as I want to render a lot of animatable objects on the screen. However I have come to a more fundamental question first: Why do I even need to use it? ...
0
votes
2answers
2k views

How to determine the point of intersection of two lines? [closed]

I have two lines say P1( 0, -1, 0, -1 ) and P2( -1, 0, 0, -1 ). Since I'm working in 2D, there is no Z component. The x,y,z components are normals and the w component is the distance from origin. I am ...
1
vote
0answers
375 views

Geometry shader and triangle adjacency

I'm currently trying to change my project to use GL_TRIANGLE_ADJACENCY instead of GL_TRIANGLES. Following this question, I have managed to construct my index buffer fine, but when it comes to the ...
2
votes
1answer
83 views

GL_TRIANGLE_ADJACENCY and glDrawElements

So I've not been able to find much online about how data should be stored for triangle adjacency. Currently I calculate my adjacent using half-edges (mention in an answer here). But do I store this ...
2
votes
2answers
93 views

Decomposing a collision grid into a set of boxes

I'm looking for a decent algorithm to decompose a collision grid (e.g. bool[w,h])... ...into a non-overlapping set of boxes (e.g. List<Rectangle>). The solution does not have to be the ...
1
vote
1answer
925 views

How do I find the circumcenter of a triangle in 3D?

I want to find the circumcenter of a triangle. Wolfram only shows how to find the circumcircle of a triangle in R2. How can I find the circumcenter of a triangle in R3?
1
vote
1answer
235 views

Batching and performances

I'm trying to understand batching and I'm not sure to understand how to do that, can I have more informations please? Here is what I found for the moment: Batching informations There is many types ...
10
votes
2answers
455 views

World Bounds - (0, Size) or (-HalfSize, HalfSize)?

When creating a game space in which to move, draw and collide objects, is it better to have the (0,0) point, or the (0,0,0) point, be in the very center of your space, such that the bounds of the ...
14
votes
3answers
6k 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 ...
7
votes
3answers
570 views

How do I target a tank turret with an offset barrel?

I have a tank model consisting of multiple parts, a body, a turret and the barrel of the gun. The turret is offset from the body origin and can rotate around the Y axis(up). The barrel is connected to ...
0
votes
1answer
253 views

DirectX 11, using Tessellation & Geometry shader in a single pass

Before all, sorry for my poor english ! With DirectX 11, i'm trying to create a random map full with GPU. Using Hull shader stage, I'm managing LOD with tessellation. Using Domain shader stage, I'm ...
1
vote
1answer
83 views

Which Graphics/Geometry abstraction to choose?

I've been thinking about the design for a browser app on the HTML5 canvas that simulates a 2D robot zooming around, sensing the world around it. I decided to do this from scratch just for fun. I need ...
5
votes
1answer
194 views

A* search in hexagonal grid with minimum turn radius

I need to run an A* search through a hexagonal grid. However, I have one nasty constraint: my vehicle can only turn so sharp. It has a specified minimum turn radius. I can't quite see how to translate ...
3
votes
1answer
117 views

Vertices shaking with large camera position values

Basicly when i set the position of my camera (my character in game) to a high value, the geometries seems to be shaking, the higher the position value, the more they shake. On low position values you ...
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 - ...
23
votes
4answers
2k views

Is the Manhattan distance monotonic when used as heuristic function?

I have a square-based map. Only horizontal and vertical movement is allowed (no diagonals). Movement cost is always 1. I'm implementing an A* algorithm on that map, using the Manhattan distance as a ...
2
votes
2answers
152 views

Calculating specific coordinate along a path

Let's say I have a path comprised of a sequence of points that are connect by lines and arcs. The entire path has some specific length. Let's call that length 100. What would be the mechanism to ...
2
votes
1answer
565 views

Collision avoidance (AI)

Now my 3D model has complete AI behaviours, but my model has no collision avoidance while he is moving towards the player! Because of this, he gets stuck in front of 3D blocks sometimes. I think the ...
6
votes
1answer
747 views

Procedural Geometry Generation

I have recently been looking into SceneKit for OS X and noticed that there are several factory methods to create geometric shapes such as: Box, Capsule, Cone, Cylinder, Plane, Pyramid, Sphere, Torus ...
0
votes
1answer
227 views

enemy View Range , chase player

for 3D: Q1 : I want to make zone range for each enemy in the game , so that when the player in the view range he will be chased . Q2 :if I want to make enemy walk a little bit around his position ...
-1
votes
1answer
119 views

chasing , zone range

here is an image show what I am gonna to do in my XNA game , I want to check if the player is inside zone range and if yes then attack the player , I tried to do this using checking ray but it's odd ...
2
votes
1answer
580 views

How to calculate collision normal between two AxisAlignedBox's?

I'm writing a physics simulation in Ogre3D and I'm trying to figure out how to calculate the collision normal between two Ogre::AxisAlignedBox's. I am checking for collisions using the "intersects" ...
1
vote
0answers
53 views

Blender: calculation of elevation and rotation angle from plane

I have a generic plane (any location, any rotation around every axis) with its normal axis passing by the center. Then I have a generic point and I need to find the elevation and the rotation angle ...
0
votes
1answer
218 views

Issues with Sine Wave Generation and Rotation

I'm working on generating objects in sine wave that lets you specify parameters that are start x, end x, start y, and end y position. Below is the method that I used to generate the debris void ...
3
votes
2answers
169 views

What kind of projection is ScreenX=X/Z, ScreenY=Y/Z?

I have an existing class which transforms 3D vectors and projects them on a 2D plane (Camera). The code is all written in C without help from an external library. To project a single vector (X,Y,Z) ...
1
vote
1answer
143 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: ...
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 ...
1
vote
2answers
1k views

Wrong faces culled in OpenGL when drawing a rectangular prism

I'm trying to learn opengl. I did some code for building a rectangular prism. I don't want to draw back faces so I used glCullFace(GL_BACK), glEnable(GL_CULL_FACE);. But I keep getting back faces also ...
1
vote
2answers
386 views

DirectX How to Gernerate Vertices for Diamond Shape and Render it?

How to generate vertices for 3D Diamond Shape in DirectX? EDIT: I am creating an application which receive DIAMETER, CROWN, GIRDLE and PAVILION as parameter and render a model of diamond according to ...
1
vote
3answers
185 views

Geometry problem for area of sight

My player have a line of sight and all objects between the white lines, turns red. To compute this, the following conditions are met: if the angle between the yellow line and the red line are small ...
3
votes
2answers
1k views

Displaying (3D) objects' name above them

The Elder Scrolls: Morrowind has a rather interesting way to display each focused objects' name. It's all a bit fuzzy in my memory right now, but the most important part I remember perfectly: the ...
2
votes
0answers
157 views

How to trace contour of shapes with holes?

I am experimenting with the RVO2 library for collision avoidance in a 2D simulation. This library supports specifying arbitrary obstacles as a list of vertices. The obstacles must be full shapes, i.e. ...
0
votes
1answer
641 views

Rotation of Rectangle along Y-axis transformed to parallelogram

After the rotation of a rectangular view along the Y-axis, about its center, transformed into parallelogram, how do I get the rotated parallelogram coordinates? By Y-axis, I mean perpendicular to the ...