An array of numbers, symbols or expressions, arranged in row and columns. The numbers, symbols or expressions themselves are called elements or entries.

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4
votes
3answers
274 views

Matrix multiplication - Scene Graphs

I wrote a MatrixStack class in C# to use in a SceneGraph. So, to get the world matrix for an object I am suposed to use: WorldMatrix = ParentWorld * LocalTransform But, in fact, it only works as ...
0
votes
1answer
117 views

Common way to store model transformations

I ask myself what's the best way to store the transformations in a model class. What I came up with is to store the translation and scaling in a Vector3 and the rotation in a Matrix4. On each update ...
1
vote
1answer
113 views

Matrix transforms in XNA

So in my most recent 2D game I draw objects like so. _spriteBatch.Draw(_sprite, Center(), null, Color.White, _rotation, new Vector2(_sprite.Width / 2, _sprite.Height / 2), _scale, ...
0
votes
1answer
594 views

What is the difference between a modelview-projection matrix and world-view-projection matrix?

So basically I wrote a shader a long time ago that uses all World and WVP matrices. Now I am working in an engine that will only give me access to ModelView, MVP, and model to world space matrices. ...
0
votes
2answers
254 views

Is this Rotation Matrix correct?

I'm having heavly troubles with setting up a View Matrix and a Projection Matrix. It simply doesnt work. So I think my problem is related to my rotationMatrix function. I'm using this tutorial to ...
2
votes
1answer
131 views

Manual GLU.gluUnproject

Before I used GLU.gluUnproject to calculate my picking ray in my OpenGL game. Recently I switched to my own calculated matrices, and now I can forget the gluUnproject. How can I calculate the picking ...
2
votes
1answer
163 views

Optimising skeletal animation

I am implementing a skeleton system for my latest game. I am using my own linear algebra classes which already have some optimisations, such as separate transformPoint and transformVector functions ...
3
votes
2answers
3k views

OpenGL - Understanding the relationship between Model, View and World Matrix

I am having a bit of trouble understanding how these matrixes work and how to set them up in relation to one another to get a proper system running. In my understanding the Model Matrix is the matrix ...
2
votes
1answer
153 views

OpenGL Calculate Matrices

Im trying to switch from the glTranslate etc to my own Matrices, but for some reason it does not work. Here are my 2 functions to create the view- and projection matrix: public Matrix4f ...
0
votes
1answer
216 views

Sharp DX Identity Matrix, Matrix.Forward vector pointing at negative Z

I'm trying to take a steady grip on Sharp DX. Already done some work like translating, scaling and rotating objects. Now i have to calculate the rotation matrix using only direction vector and ...
0
votes
1answer
86 views

What values to construct “Projection Matrix” from?

I am curious to what standard values I should use to create a camera's projection matrix, as well as if certain measurements need to be taken if I want to represent a very small world or a very big ...
0
votes
1answer
116 views

Getting Rotation Values From A Rotation Matrix

I'm trying to get rotation values along the x, y and z axis from a matrix that can include rotation, translation and scale data. Currently I have this function to return the y rotational value: float ...
3
votes
1answer
470 views

Rotating and Translating a Node in Horde3D with Matrices and Quaternions

I have been trying to learn how to use the Horde3D rendering engine for the past couple of days, and so far I have managed to learn a decent amount and integrate Bullet Physics with it as well. My ...
0
votes
1answer
126 views

XNA Camera Positioning All Wrong

I've been working in 3DSMax for years now and decided to give XNA 4.0 a try. I've got the majority of it working, however the camera is being a pain to me and I can't discern what's gone wrong. I ...
3
votes
2answers
167 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) ...
2
votes
1answer
330 views

Negative scale in Matrix 4x4

After some rotations and to from quaternion conversions I get negative scale from Matrix 4x4, is it possible? I need that scale to draw sprite on screen so I get sprite flipped, how to deal with this ...
2
votes
2answers
231 views

Java Tetris - Matrix Rotations

I'm building Tetris in Java and am trying to use linear algebra to rotate a piece composed of 4 tiles. My friend was explaining the way to do it is: He said: "To clarify, you do need to rotate ...
4
votes
3answers
972 views

Tetris - Rotations using Linear Algebra (Rotation Matrices)

I'm making Tetris in Java and am at the point of rotations... Originally I was hardcoding each rotation: if (direction.equals("right")) { if (shape.equals("Bar")) { if ...
2
votes
1answer
175 views

Translating Viewmatrix is inverted, why?

So I've defined a Projectionmatrix, Viewmatrix and a Modelmatrix using OpenGL (LWJGL). But when I translate my Viewmatrix to +X it moves my object to the right (hence my camera is moving to the ...
0
votes
2answers
108 views

Transform translation relative to world space

What is common algorithm for translating a transform matrix relative to world space axis? E.g. Matrix M is representing some local space. When I want to translate M relative to it's own local axis, I ...
2
votes
1answer
182 views

Camera not strafing (GLSL)

I use this code in my GLSL vertex shader, where v_position is the vertex position: gl_Position = v_position * u_camera; and set u_camera as follows: meshShader.setUniformMatrix("u_camera", ...
2
votes
1answer
126 views

transformations of matrices

I'm in the process of reading up on 3d matrices and trying to following this powerpoint and had a few questions as to how to exactly determine the type of transformation from a matrix. If I have a ...
0
votes
1answer
205 views

Box2D OpenGL debug renderer convert box2d coordinates to world space

I made an OpenGL 3.x renderer for Box2D's debug draw (b2Draw base class). Unfortunately I've tried for a while now to convert the box2D units, which are meters to my internal units which are pixels. I ...
-1
votes
3answers
260 views

Directional light and matrix issues

I'm trying to implement basic directional lightning in OpenGL 3.3 by emulating the logic shown in this guide: http://www.arcsynthesis.org/gltut/Illumination/Tutorial%2009.html I do not understand ...
1
vote
0answers
102 views

Rotate Points with Object in world space

I posted this in the original stack overflow then realized that a game-dev specific one exists. I am working on personal project that requires me to have 4 points surrounding an object (1 at each of ...
2
votes
2answers
480 views

World space and model space the dummies version [closed]

I'm by no means a 3d programmer but have recently taken it upon myself to build a Voxel based game and I'm having a little trouble understanding some of the concepts around matrices (what with my ...
5
votes
1answer
345 views

Rotating plane to be parallel to given normal via change of basis

I have two planes and their respective normals. I would like to rotate the second plane, planeB, so that it is parallel to the first, planeA. To do this, I am using a change of basis to rotate each ...
1
vote
2answers
206 views

Accumulating rotations for camera

It seems there are three ways to store a camera's rotation: in angles, view matrix or quaternion. I was using euler angles since when I used a matrix it had a tendency to accumulate rounding errors ...
1
vote
1answer
160 views

Proper approach to handle transformation matrix and extract its components

Basically I have a Transformation component object with following structure(pseudo): TransformComponent{ Vec3 position; Vec3 rotation; //in euler angles Vec3 scale; Mat4 worldMatrix; ...
0
votes
1answer
243 views

Ways to “invert Z-axis” in shader-based core-profile OpenGL?

In my hobbyist shader-based (non-FFP) GL (3.2+ core) "engine", everything in world-space and model-space is by design "left-handed" (and to stay that way), so X-axis goes from -1 ("left") to 1 ...
2
votes
1answer
381 views

How can I create a 2D camera with upscaling and translation?

I've computed a Viewport that is fair in size (a proper aspect ratio to the given device) and then I calculate my ScaleMatrix like so: scaleMatrix = Matrix.CreateScale( (float) ...
1
vote
2answers
2k views

What matrix operations do I perform to translate then rotate then translate then rotate?

In an android game I want to draw a running leg. To output the thigh I do something like: // legCX,legCY is the location on screen about which the leg rotates. Matrix m = new Matrix(); ...
5
votes
3answers
2k views

Mapping 3D object coordinates to 2D screen coordinates with perspective projection

Sort of following on from where this person was in their topic: Matrix for 2D perspective What I have at the moment is a transformation matrix that's defined as follows: http://pastebin.com/GM6BhP0R ...
7
votes
2answers
1k views

How can you extract orientation from a transformation matrix?

I have a 4x4 transformation matrix M, and I want to find out the shape of a sphere when transformed by M. (Sphere is at the origin and has radius 1.) I know I can find the center by just multiplying ...
0
votes
1answer
62 views

Assigning bone transform in every draw a good idea?

In my Draw method, I am doing the following: thisMesh.CopyAbsoluteBoneTransformsTo(transforms); Is this a good idea? Or should I do this once at the constructor level?
1
vote
1answer
408 views

2D Matrix Transformation (with a Player and Ground)

I have a simple game that I'm trying to do for learning purposes, but Matrices are a bit hard, especially in DirectX. I currently have a tilesystem that renders tiles at the screen and a character ...
0
votes
1answer
740 views

All of my matrix functions not working? OpenGL ES 2.0

I am trying to make a projection matrix scaling the screen and making a coordination system. For some reason I don't think any of my matrix calling is working... the 3 function I am using are ...
3
votes
1answer
845 views

Rotating 3d plane to XY plane

I have a triangle in 3d space and would like to create a grid over the triangle, such as in the image below. The purpose of this is to store information about each block of the grid. In order to ...
1
vote
0answers
377 views

Stacking Drawing Matrix for SpriteBatch in XNA

I'm trying to make a 2D engine for XNA with SpriteBatch. My object unit is Entity, which can include other Entities as its children. However, when drawing them, the rotation and scaling stacking do ...
2
votes
1answer
305 views

Handling Origin/Anchor Points in a Scene Graph

I'm trying to implement a simple scene graph on iOS using GLKit but handling origin/anchor points is giving me fits. The requirements are pretty straightforward: There is a graph of nodes each with ...
1
vote
0answers
180 views

How do I implement a physics gun?

I'm currently trying to implement a physics gun for my game. What I want is for the entity to stay in the same position on the screen no matter how I wiggle the camera about, what is the correct way ...
1
vote
1answer
204 views

Is my idea of how to use matrices to layer 2D on top of 3D correct?

I'm new to using matrices, so I'd like some input on whether I've understood the use of them in the context described in the title. Right now I have a small Direct3D 11-based game engine which ...
0
votes
0answers
64 views

Transform a Screen Delta

I have a delta in screen coordinates that I want to transform to a 3d delta in world space. The delta is in this case a movement across the (x,y) coordinates in screen space on the near projection ...
1
vote
2answers
662 views

Matrix Rotation with three Angles

I want to rotate a form with three given angles fo each of the three axis. But the GLM rotation function takes only one angle and a vector as arguments. How can I convert between both formats?
4
votes
1answer
238 views

How attach a model with another model on a specific bone?

I meet a difficulty attached to a model to another model on a "bone" accurate. I searched several forums but no result. I saw that many people have asked the same question but no real result see no ...
2
votes
1answer
543 views

Scaling along an arbitrary axis (Dealing with non-uniform scale)

I'm trying to build my own little engine to get more familiar with the concepts of 3D programming. I have a transform class that on each frame it creates a Scaling Matrix (S), a Rotation Matrix from ...
1
vote
2answers
702 views

convert orientation vec3 to a rotation matrix

I've got a normalized vec3 that represents an orientation. Each frame of animation, an object's orientation changes slightly, so I add a delta vector to the orientation vector and then normalize to ...
8
votes
4answers
3k views

Staggered Isometric Map: Calculate map coordinates for point on screen

I know there are already a lot of resources about this, but I haven't found one that matches my coordinate system and I'm having massive trouble adjusting any of those solutions to my needs. What I ...
0
votes
1answer
222 views

Y Axis inverted on vertex output

I've got my project running and somehow it seems my vertex y components are inverted. 10 in the positive on Y goes down and 10 negative on the Y axis goes up. I can't find anything with the ...
1
vote
1answer
567 views

How to do geometric projection shadows?

I have decided that since my game world is mostly flat I don't need better shadows than geometric projections - at least for now. The only problem is I don't even know how to do those properly - that ...