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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2
votes
1answer
978 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 ...
2
votes
2answers
1k 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 ...
9
votes
4answers
4k 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
338 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 ...
2
votes
1answer
706 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 ...
6
votes
1answer
653 views

How can I attach a model to the bone of another model?

I am trying to attach one animated model to one of the bones of another animated model in an XNA game. I've found a few questions/forum posts/articles online which explain how to attach a weapon ...
4
votes
1answer
335 views

How to transform mesh components?

I am attempting to transform the components of a mesh directly using a 4x4 matrix. This is working for the vertex positions, but it is not working for the normals (and probably not the tangents ...
1
vote
0answers
329 views

Drawing two orthogonal strings in 3d space in Android Canvas?

I want to draw two strings in canvas. The first string must be rotated around the Y axis, for example 45 degrees. The second string must start at the end of the first string and also it must be ...
2
votes
2answers
376 views

How should I organize my matrices in a 3D game engine?

I'm working with a group of people from around the world to create a game engine (and hopefully a game with it) within the next upcoming years. My first task is to write a camera class for the engine ...
6
votes
4answers
1k views

How can I generate a view or projection matrix for OpenGL 3.+

I'm transitioning from OpenGL 2 to OpenGL 3.+ and to GLSL 1.5. I'm trying to avoid using the deprecated features. My question how do we now generate the view or projection matrix. I was using the ...
0
votes
1answer
252 views

Stage3D: Camera pans the whole screen

I am trying to create a 2D Stage3D game where you can move the camera around the level in an RTS style. I thought about using Orthographic Matrix3D functions for this but when I try to scroll the ...
1
vote
0answers
307 views

Matrix.CreateBillboard centre rotation problem

I'm having an issue with Matrix.CreateBillboard and a textured Quad where the center axis seems to be positioned incorrectly to the quad object which is rotating around a center point: Using: ...
3
votes
2answers
2k views

The purpose of using invert and transpose

In openGl ES and the World of 3D - why use the invers matrix? The thing is that I dont have any intuition to, why it is used, therefore please correct me: As fare as I understand, it is used in ...
1
vote
1answer
181 views

Deformation of Sphere using Transformations

I have a graphic related question. I need to have a transformation matrix that I have no idea about what it is. The problem is to create right image from the right sphere. I created those images in ...
1
vote
1answer
234 views

Camera lookAt target changes when rotating parent node

have the following issue.I have a camera with lookAt method which works fine.I have a parent node to which I parent the camera.If I rotate the parent node while keeping the camera lookAt the target , ...
0
votes
1answer
146 views

coordinate transformation

I have two coordinate systems, like so How can I transform a point on the one of the coordinate system to other ? Pxyz = M . Px'y'z' what is M ?
1
vote
0answers
243 views

How do I convert my matrix from OpenGL to Marmalade?

I am using a third party rendering API, Marmalade, on top of OpenGL code and I cannot get my matrices correct. One of the API's authors states this: We're right handed by default, and we treat y ...
2
votes
2answers
1k views

How can I reflect a point with respect to the plane?

How can I reflect a point with respect to a plane? Example: I have three points (0,0,2), (4,0,0) and (0,8,0). And I have a point (x,y,z). From these, I want derive a composite transformation matrix. ...
5
votes
1answer
191 views

How can I convert OBJ data into CSS3D transformations?

I want to convert the data in a 3D .obj file (vertices, normals, faces) to CSS3D (width, height, rotateX,Y,Z and/or similar transforms). I found a bunch of formulae and what-not, but 3D isn't my ...
0
votes
1answer
104 views

How to Draw texture between 2 Vector3

My scenario: RTS combat style, 1 unit fires beam on another unit My problem is i want to draw a flat texture between 2 Vector3 points. I have looked at various Billboarding styles but that doesn't ...
8
votes
1answer
12k views

How does gluLookAt work?

From my understanding, gluLookAt( eye_x, eye_y, eye_z, center_x, center_y, center_z, up_x, up_y, up_z ); is equivalent to: glRotatef(B, 0.0, 0.0, 1.0); ...
2
votes
1answer
236 views

Movement on the X an Z axis are combined?

This is probably a stupid question, but I'm trying to simply move a 3D object up, down, left, and right (Not forward or backward). The Y axis works fine, but when I increment the object's X position, ...
58
votes
9answers
21k views

Why do we move the world instead of the camera?

I heard that in an OpenGL game what we do to let the player move is not to move the camera but to move the whole world around. For example here is an extract of this tutorial: OpenGL View matrix ...
2
votes
1answer
578 views

Billboarding restricted to an axis (cylindrical)

I have succesfully created a GLSL shader for a billboarding effect. I want to tweak this to restrict the billboarding to an arbitrary axis, i.e. a billboarded quad only rotates itself about the ...
3
votes
2answers
1k views

How can I implement smooth rotation from one direction to another?

I'm having a problem with animating rotations with 1Matrix.CreateRotationY() with my basic 3D game. Based on where you click the mouse, I want the 3D object to rotate to that direction and then move. ...
3
votes
2answers
491 views

3D rotation matrices deform object while rotating

I'm writing a small 3D renderer (using an orthographic projection right now). I've run into some trouble with my 3D rotation matrices. They seem to squeeze my 3D object (a box primitive) at certain ...
1
vote
1answer
715 views

how can i get rotation vector from matrix4x4 in xna?

i want to get rotation vector from matrix to realize some parent-children system for models. Matrix bonePos = link.Bone.Transform * World; Matrix m = Matrix.CreateTranslation(link.Offset) * ...
0
votes
1answer
1k views

Building View Matrix in Direct3D11

Am I doing it right? I converted this. m_ViewMatrix = XMMatrixLookAtLH(XMLoadFloat3(&m_Position), lookAtVector, upVector); to this one. XMVECTOR vz = XMVector3Normalize( lookAtVector - ...
0
votes
2answers
1k views

OpenGL, objects disappear at a certain z distance

I'm writing a managed OpenGL library in C++, and I'm having a pretty annoying problem. Whenever I set an objects Z coordinate to -2.0 or lower, the object disappears. And at coordinates 0 through ...
3
votes
1answer
164 views

How to make an object stay relative to another object

In the following example there is a guy and a boat. They have both a position, orientation and velocity. The guy is standing on the shore and would like to board. He changes his position so he is ...
3
votes
1answer
182 views

Extract derived 3D scaling from a 3D Sprite to set to a 2D billboard

I am trying to get the derived position and scaling of a 3D Sprite and set them to a 2D Sprite. I have managed to do the first part like this: var p:Point = sprite3d.local3DToGlobal(new ...
2
votes
2answers
1k views

Rotating a child shape relative to its parent's orientation

When rotating a shape using a quaternion value I also wish rotate its child shape. The parent and child shapes both start with different orientations but their relative orientations should always be ...
1
vote
1answer
162 views

Orthogonal projection and world transform

I'm reading about projection matrix. Needs of perspective projection is obvious, but I'm not sure about orthogonal projection. Because orthogonal projection effect looks possible with only world ...
2
votes
1answer
100 views

Camera closes in on the fixed point

I've been trying to create a camera that is controlled by the mouse and rotates around a fixed point (read (0, 0, 0)), both vertical and horizontal. This is what I've come up with: camera.Eye = ...
0
votes
1answer
134 views

What's the standard location of a 3D clipping box?

The way I understand 3D rendering, polygons are transformed using several matrices, and they are then clipped if they are not inside a certain box, before projecting the box onto the screen. Before ...
2
votes
1answer
366 views

Does XNA 4 support 3D affine transformations for 2D images?

Looooong story short I'm essentially trying to code Mode 7 in XNA. Before I continue bashing my brains out in research and various failed matrix math equations; I just want to make sure that XNA ...
3
votes
1answer
448 views

D3DXMatrixDecompose gives different quaternion than D3DXQuaternionRotationMatrix

In trying to solve this problem, I tracked down the problem to the conversion of the rotation matrix to quaternion. In particular, consider the following matrix: -0.02099178 0.9997436 -0.008475631 0 ...
3
votes
2answers
691 views

How to derive euler angles from matrix or quaternion?

Currently working on steering behavior for my AI and just hit a little mathematical bump. I'm in the process of writing an align function, which basically tries to match the agent's orientation with ...
2
votes
1answer
221 views

Problem with D3DXMatrixReflect

Currently I am trying to reflect a sky sphere into a flat piece of geometry which is acting as water. The sphere is very small, it follows the camera on all 3 axis and the z-buffer is turned off so it ...
0
votes
1answer
546 views

Correct Rotation and Translation with a 4x4 matrix

I am using a 4x4 matrix to transform verts in a shader. I multiply an identity matrix by a rotation matrix by a translation matrix. I am trying to first rotate the verts and then translate them, ...
3
votes
2answers
419 views

Rotating voxels in 3d space amongst the x axis

I have a very simple voxel engine and so far it works based on coordinates, e.g. x, y, z. I was wondering if there is a formula for rotating groups of voxels/coordinates from the x axis(e.g. [0, 1, ...
0
votes
2answers
261 views

get coordinates of origin of coordinate system in second coordinate system by knowin matrices of one point in bith systems

Situation, two coordinate systems A, B. origins Oa, Ob. I have one point, for which i know modelview matrix (translatoin/orientation) in both systems. And what i need to get is modelview matrix of Ob ...
1
vote
1answer
175 views

Can't work out how matrix is applied to 2D vertices

I have a texture, some 2D vertices, and a matrix. The matrix is used to calculate the texture coordinates for each vertex, but the problem is that the matrix comes with absolutely no documentation and ...
2
votes
3answers
2k views

glGetFloatv – should it be avoided? Can it be replaced?

Platform is OpenGL ES 1.x. I am using glGetFloatv() to get MODELVIEW matrix. This allows me to compute points, where I need to draw a shadow effect. This is very handy, as I can forget about ...
1
vote
0answers
267 views

Getting and Setting Rotation in XNA around the Center of my Model with XNA

Alright, so I'm currently debating how I want to do this. Basically this is what I'm trying to accomplish. I've created a system to allow me to make my environment a little bit easier. I'm ...
0
votes
2answers
1k views

OpenGL matrix vs DirectX matrix

I'm working on an animation and model exporter from Maya to use within my game. Currently, models work perfectly, and animations have some issues with the joints. Since Maya works in an OpenGL ...
1
vote
0answers
214 views

what space is this Matrix in? [closed]

In Blender 2.6 API, PoseBone is used for animating a bone. PoseBone.matrix is one way to do that. API says PoseBone.matrix is in "object space". ...
2
votes
1answer
283 views

Transformation matrix that maps a window

I'm currently learning OpenGL at uni, and they give us questions to help us learn (these are not worth anything), however I'm stuck on this one question and would have to travel over an hour and a ...
-2
votes
1answer
236 views

Why doesn't my MatrixStack class work? [closed]

I've been trying to get openGLES2 to work on my Android device and this is starting to drive me insane. I've spent well over ten hours now trying to get this to work. I just don't understand anymore. ...
2
votes
1answer
174 views

Understanding Tensors [closed]

I don't seem to be able to visualize tensors. I am reading The Morgan Kauffman Game Physics Engine Development and he uses tensors to represent aerodynamics but he doesn't explain them so I am not ...