# Tagged Questions

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

126 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 ...
311 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: ...
743 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 ...
183 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 ...
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 ...
3k 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 ...
168 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 ...
4k views

### 2D isometric: screen to tile coordinates

I'm writing an isometric 2D game and I'm having difficulty figuring precisely on which tile the cursor is. Here's a drawing: where xs and ys are screen coordinates (pixels), xt and yt are tile ...
247 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 ...
3k 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> ...
422 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 ...
4k 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 ...
1k 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 ...
179 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?
119 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 ...
5k 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 ...
379 views

### Partial recalculation of visibility on a 2D uniform grid

Problem Imagine that we have a 2D uniform grid of dimensions N x N. For this grid we have also pre-computed a visibility look-up table, e.g. with DDA, which answers the boolean query is cell X visible ...
120 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 ...
163 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 ...
58 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 ...
1k 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 ...
724 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 ...
514 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 ...
466 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 = [ ...
558 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 ...
613 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 ...
1k 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 ...
952 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 ...
2k 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 ...
279 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 ...
190 views

### Intersect of vector and triangle side

I'm trying to create a triangular touch surface for iOS where the user can drag around a point inside this triangle. Using information from this page, it is easy to figure out if the dragged point is ...
1k views

### Repairing back-facing triangles without user input

My 3D application works with user-imported 3D models. Frequently, those models have a few vertices facing into the wrong direction. (For example, there is a 3D roof and a few triangles of that roof ...
914 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 ...
559 views

### Intersection points of plane set forming convex hull

Mostly looking for a nudge in the right direction here. Given a set of planes (defined as a normal and distance from origin) that form a convex hull, I would like to find the intersection points that ...
1k views

### How to perform simple collision detection?

Imagine two squares sitting side by side, both level with the ground like so: A simple way to detect if one is hitting the other is to compare the location of each side. They are touching if all of ...
644 views

### How do I make a low pass filter (average of readings over time) for compass?

I'm making a prototype for android that pulls compass data from the phone. I want to stabilize it so it is less jerky, by taking the average of the last couple of readings. I have done this for ...
541 views

### Calculate path of laser beam?

Lets say we have a laser beam emitter that has a position and an angle (in a 2D world to simplify things). The laser emitted from that emitter will start at that position, and continue heading in the ...
383 views

### High school-level geometry book focusing on game dev for struggling student?

Here's the situation. My brother, a freshman in high school, isn't doing too well in geometry. Partially because he doesn't do half the work, but partially because he seems to have genuine ...
1k views

### Testing whether two cubes are touching in space

Does anyone have any clean ideas on testing whether two cubes in 3D space touch? By touch I mean, touch at corners or on a face or on an edge. Say that the cubes are axis aligned and there is no ...
294 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 ...
413 views

### Running geometry shader only once

(Unfortunately couldn't find the answer myself) Does a neat way to cache the geometry shader results in Direct3D10 or OpenGL exist? (preferably Direct3D10). I'm building my geometry based on texture ...
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 ...
550 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, ...
1k 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 ...
374 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 ...
238 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 ...
342 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.
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### 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 ...