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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1
vote
1answer
220 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
139 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
239 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
0answers
168 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
11k 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
233 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, ...
56
votes
9answers
19k 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
530 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
478 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
692 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
160 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
179 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
131 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
356 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
439 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
647 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
218 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
516 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
397 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
257 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
174 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
1k 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
259 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
281 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
170 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 ...
0
votes
1answer
328 views

3d world vertex translation to go to 2d screen coords

My technical english is a little rusty so to avoid misunderstands please be patient with me :) I will try to be brief and clear Situation: - I have a 2d sprite character on the screen - I've just ...
5
votes
1answer
430 views

apply non-hierarchial transforms to hierarchial skeleton?

I use Blender3D, but the answer might not API-exclusive. I have some matrices I need to assign to PoseBones. The resulting pose looks fine when there is no bone hierarchy (parenting) and messed up ...
1
vote
3answers
364 views

Inverting matrix then decomposing gives different quaternion than decomposing then inverting the quat

I'm getting different signs when I convert a matrix to quaternion and invert that, versus when I invert a matrix and then get the quaternion from it: Quaternion a = Quaternion.Invert(getRotation(m)); ...
1
vote
1answer
2k views

2D Quads : Translation with OpenGL ES 2.0 on Android [closed]

I have a simple 2D engine that renders 2D textured quads, and right now I can scale the quad or rotate it, but when I try to translate it I have a strange distortion (the quad is squashed in the half ...
2
votes
1answer
474 views

Finding a suitable axis-angle to avoid gimbal lock

In OpenGL the camera faces the -z axis with the +y axis pointing up. I am using quaternions to represent the orientation of my objects (which works well) and am trying to do the same for the camera. I ...
0
votes
0answers
481 views

Calculating the correct roll from a bone transform matrix

Read this forum topic for more info: http://blenderartists.org/forum/showthread.php?260602-transform-matrix-to-bone-%28head-tail-roll%29-bug I'm trying to get my Blender3d modeller importer to create ...
1
vote
0answers
173 views

reflection plane 3d

Hey there I'm trying to create a plane that can have a texture on it and reflect the 3d elements around it. for example a plane with a laminate floor texture and above it a cube rotating. I want the ...
1
vote
1answer
625 views

importing animations in Blender, weird rotations/locations

This is for the Blender 2.6 API. There are two problems: 1. When I import a single animation frame from my animation file to Blender, all bones look fine. But when I import multiple (all of the ...
0
votes
1answer
511 views

Optimizing hierarchical transform

I'm transforming objects in 3D space by transforming each vector with the object's 4x4 transform matrix. In order to achieve hierarchical transform, I transform the child by its own matrix, and then ...
0
votes
2answers
606 views

getting bone base and tip positions from a transform matrix?

I need this for a Blender3d script, but you don't really need to know Blender to answer this. I need to get bone head and tip positions from a transform matrix read from a file. The position of base ...
3
votes
0answers
278 views

Blender - creating bones from transform matrices [closed]

Notice: this is for the Blender 2.5/2.6 API. Back in the old days in the Blender 2.4 API, you could easily create a bone from a transform matrix in your 3d file as EditBones had an attribute named ...
6
votes
1answer
241 views

Matrices: Arrays or separate member variables?

I'm teaching myself 3D maths and in the process building my own rudimentary engine (of sorts). I was wondering what would be the best way to structure my matrix class. There are a few options: ...
4
votes
1answer
1k views

Multiplication for MVP matrices: Any benefits to doing so within the vertex shader?

I'd like to understand under what circumstances (if any) it is worth doing MVP matrix multiplication inside a vertex shader. The vertex shader is run once per vertex, and a single mesh typically ...
2
votes
1answer
683 views

Translate along local axis

I have an object with a position matrix and a rotation matrix (derived from a quaternion, but I digress). I'm able to translate this object along world-relative vectors, but I'm trying to figure out ...