A branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space.
1
vote
0answers
29 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
55 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
110 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) ...
0
votes
0answers
47 views
Top down 2D camera in relation to keyboard commands
I have a basic 2D camera:
transform =
Matrix.CreateTranslation(-position.X, -position.Y, 0) *
Matrix.CreateRotationZ(-rotation) *
Matrix.CreateScale(new Vector3(zoom, zoom, 1)) *
...
1
vote
2answers
98 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 ...
2
votes
0answers
88 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 ...
3
votes
2answers
184 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 ...
1
vote
1answer
64 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
0answers
59 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. ...
1
vote
1answer
76 views
Moving an object toward another object on sphere knowing their quaternions
I have a sphere centered in world origin. On the sphere surface I have two objects and I know their quaternions (rotation around sphere).
Currently my movement works on Vector2 inputs (cannot change ...
0
votes
1answer
122 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 ...
1
vote
3answers
143 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 ...
-5
votes
3answers
200 views
in the shadow of a sphere [duplicate]
(Related, but somewhat different, to my previous question)
How can I determine in a fragment shader if a fragment is in the shadow of a sphere?
That is, if it is occluded by the sphere and is past ...
1
vote
1answer
54 views
Build a Cube/Prism from other varied Cubes/Prisms [closed]
I'm wondering, are there any algorithms or theories in existence (that aren't patented/proprietary/protected) that would take a series of 3d rectangular prisms (or cubes but a cube is a prism) and ...
2
votes
1answer
259 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" ...
3
votes
1answer
146 views
How do I render a filled and stroked path using OpenGL?
I want to render a 2-dimensional geometric path consisting of Bézier curves and straight lines. Paths can be concave.
What is the most efficient way to draw this using modern OpenGL? Can I do this ...
0
votes
1answer
33 views
How to linearly blend between multiple points, deviating from a default point?
I have a set of 3D points that I need to "blend" between. Lets say I have points [A,B,C] and I have the amount I want to blend each as [0.5, 0.2, 0.8], how can I blend between these points with the ...
1
vote
1answer
74 views
How to linearly “blend” between multiple 3D points?
I have a set of 3D points that I need to "blend" between. Lets say I have points [A,B,C] and I have the amount I want to blend each as [0.5, 0.2, 0.8], how can I blend between these points with the ...
6
votes
3answers
370 views
Transforming a primitive tetrahedron into a primitive icosahedron?
I've created a tetrahedron by creating a BoundingBox and building the faces of the tetrahedron within the bounding box as follows (see image as well):
VertexPositionNormalTexture[] vertices = new ...
5
votes
6answers
230 views
How do I calculate distance from a point to a rectangle?
I have a 2D rectangle with x, y position, height and width, and a randomly positioned point nearby.
Is there a way to check if this point might collide with the rectangle if it is closer than a ...
23
votes
1answer
744 views
How do you turn a cube into a sphere?
I'm trying to make a quad sphere based on an article, which shows results like this:
I can generate a cube correctly:
But when I convert all the points according to this formula (from the page ...
2
votes
2answers
91 views
Splitting Graph into distinct polygons in O(E) complexity
If you have seen my last question:
trapped inside a Graph : Find paths along edges that do not cross any edges
How do you split an entire graph into distinct shapes 'trapped' inside the graph(like ...
5
votes
1answer
97 views
trapped inside a Graph : Find paths along edges that do not cross any edges
This is a graph based platformer level and the round shapes are creatures.
I am looking for a path traveling along edges that does not cross other edges(To simulate the creature crawling on the ...
1
vote
2answers
792 views
Rotate an object given only by its points?
I was recently writing a simple 3D maze FPP game. Once I was done fiddling with planes in OpenGL, I wanted to add support for importing Blender objects. The approach I used was triangulization of the ...
2
votes
1answer
93 views
Finding the normals of an oriented bounding box?
Here is my problem.
I'm working on the physics for my 2D game.
All objects are oriented bounding boxes (OBB) based on the separate axis theorem.
In order to do collision resolution, I need to be ...
18
votes
5answers
475 views
Moving CW or CCW?
Lets say we have a jagged shape:
And two creatures moving along it's outline.
Then we smooth the shape completely by pulling the corners out.
We get this:
It is easy to see now that Orange is ...
0
votes
1answer
390 views
“LNK2001: unresolved external symbol” when trying to build my program
I get the following error(s) on my program that captures the mouse and then draws a line.
Errors:
1>------ Build started: Project: Capture_Mouse_Line, Configuration: Debug Win32 ------
1> ...
8
votes
2answers
544 views
Arbitrary Rotation about a Sphere
I'm coding a mechanic which allows a user to move around the surface of a sphere. The position on the sphere is currently stored as theta and phi, where theta is the angle between the z-axis and the ...
9
votes
2answers
317 views
How to limit click'n'drag movement to an area?
I apologize for the somewhat generic title. I'm really don't have much clue about how to accomplish what I'm trying to do, which is making it harder even to research a possible solution.
I'm trying ...
1
vote
2answers
107 views
ricocheting off a wall
I have a capsule (sphere sweep) that I've computed the collision on a mesh with.
I know the point of impact and normal of the face it collides with.
My moving object - I'm using a capsule to ...
1
vote
2answers
657 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 ...
5
votes
4answers
244 views
Would like some help in understanding rendering geometry vs textures
So I was just pondering whether it is more taxing on the GPU to render geometry or a texture. What I'm trying to see is whether there is a huge difference in rendering two scenes with the same setup:
...
9
votes
3answers
318 views
Are the first 3 parameters 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?
4
votes
3answers
239 views
How to get distance from point to line with distinction between side of line?
I'm making a 2d racing game. I'm taking the nice standard approach of having a set of points defining the center of the track and detecting whether the car is off the track by detecting its distance ...
1
vote
1answer
88 views
Intersection of player and mesh
I have a 3D scene, and a player that can move about in it.
In a time-step the player can move from point A to point B. The player should follow the terrain height but slow going up cliffs and then ...
0
votes
1answer
143 views
moving in the wrong direction
Solution:
To move a unit forward:
forward = Quaternion(0,0,0,1)
rotation.normalize() # ocassionally
...
pos += ((rotation * forward) * rotation.conjugated()).xyz().normalized() * speed
I think the ...
0
votes
1answer
48 views
applying rotation and speed to move user
My player has a position (vec3), rotation (quaternion) and speed.
I have a fixed time step. At each tick, I work out from key-state etc what rotation and speed adjustments to make.
How do I now ...
1
vote
2answers
145 views
The distance to a line from a point, find the constant values?
I have 3 points, (x1, y1), (x2, y2), (x3, y3)
I should find the AH height. For this i must use:
How can i find each "a", "b" and "c" values?
3
votes
3answers
673 views
Textureing subdivided Icosahedron in XNA, seam problem
*Look below for the updated source code*
I have started to to make some different types of objects and create them by code in XNA. Right now I have finished the code for creating a Icosahedron. And ...
14
votes
4answers
449 views
Algorithm for creating adjacent triangles
I have a system where you can click once to place a node in a scene. When you place 3 nodes, it forms a triangle. When you place any future nodes, it creates a new triangle by joining that node to the ...
4
votes
2answers
334 views
Geometry vs sprites
I'm developing an android game, where the enemies are geometrical shapes. Performance is a main goal for me so I was wondering if defining shapes directly in OpenGL would be more efficient than using ...
1
vote
2answers
208 views
Separation of axis theorem implementation
I have been following the this guide to implement this. My current implementation is the following:
class SAT {
SAT();
bool collides(Rectangle rect1, Rectangle rect2){
var axises = [
...
5
votes
2answers
205 views
Robust line of sight test on the inside of a polygon with tolerance
Foreword
This is a followup to this question and the main problem I'm trying to solve. My current solution is an hack which involves inflating the polygon, and doing most calculations on the inflated ...
3
votes
3answers
189 views
Adding tolerance to a point in polygon test
I've been using this method which was taken from Game Coding Complete to detect whether a point is inside of a polygon. It works in almost every case, but is failing on a few edge cases, and I can't ...
8
votes
2answers
855 views
How do I determine if one polygon completely contains another?
I have 2 polygons. I know the vertex coordinates of both polygons. What's the best way to check if one is completely inside the other? For example, the algorithm should only recognize the black ...
0
votes
1answer
259 views
Determining and culling non-visible vertices
Ahoy!
After posting my previous question on tile maps, i've been tinkering with an implementation i'm rather pleased with so far but would like to gather some more information about submitting ...
1
vote
2answers
632 views
Render a polyline with rounded joints
I have a list of points (3D) and want to draw a line connecting all points with a specified width. The line should be rendered in OpenGL (using OSG) as triangles.
The real challenge of this task is to ...
0
votes
2answers
209 views
ray polygon intersection
Hi, I am looking for an elegant way to do ray and polygon intersections in 2d. I don't care about languages.
Now what I'm doing is taking a line that lies on the ray (with a screen length) and ...
0
votes
1answer
334 views
Easy way to project point onto triangle (or plane)
I have a mesh of triangles (navigation mesh), and a point in 3d space. This point should be "over" one of the triangles all the times. I'm trying to determine which triangle is the one the point is ...
0
votes
1answer
134 views
Minimap Around Perimeter of Screen, Code Provided
What I'm essentially trying to do is what a lot of FPS's nowadays do in regards to their HUD. When an objective is off-screen, a small icon / symbol is shown on the perimeter of the screen, basically ...
