Tagged Questions

2
votes
2answers
149 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 ...
0
votes
1answer
54 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?
0
votes
0answers
126 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
147 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 ...
0
votes
0answers
88 views

Camera Projection back Into 3D world, offset error

I'm using XNA to simulate a robot in a 3D world and then do image analysis on what the camera sees. I have my camera looking down in front of the direction that the robot is going, and I have the ...
6
votes
1answer
243 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 ...
1
vote
0answers
143 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: ...
2
votes
1answer
204 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, ...
2
votes
1answer
88 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 = ...
2
votes
1answer
220 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 ...
1
vote
0answers
168 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
1answer
237 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 ...
2
votes
1answer
421 views

Why use 3d matrix and camera in 2D world for 2d geometric figures?

I'm working in XNA on a 2d isometric world/game and I'm using DrawUserPrimitives to draw some geometric figures... I saw some tutorials about creating dynamic shadows but I didn't understood why they ...
0
votes
2answers
296 views

Vectors from matrix

In XNA you can get front/back/left/right vector of Matrix class. How get these vectors without XNA, through C++ using standart 4x4 matrix ? I dont understand what exactly they mean but found them very ...
3
votes
1answer
229 views

Retrieving model position after applying modeltransforms in XNA

For this method that the goingBeyond XNA tutorial provides, it would be really convenient if I could retrieve the new position of the model after I apply all the transforms to the mesh. I have edited ...
0
votes
2answers
3k views

Scaling Model in XNA, keep position

I am trying to create a little fun 3D game in XNA, but I am having some problems with scaling my models. I use models from random sites, so my battleship is for an example 10 times larger than my ...
3
votes
1answer
1k views

Moving a rotated model in XNA

This seems like a simple problem with an equally simple solution that is invisible to me. I have a model that spawns at the origin and looks at my player model wherever it goes. I would like it to ...
1
vote
4answers
1k views

Rotating a model AND translating it forward in XNA

I have this enemy class, and I want it to 1) Spawn at a certain place Vector3 pos 2) Rotate to face my player position 3) Move forward As this code is now, it will appear at it's specified place: ...
5
votes
1answer
342 views

How do I create weapon attachments?

My question is; I am developing a game for XNA and I am trying to create a weapon attachment for my player model. My player model loads the .md3 format and reads tags for attachment points. I am able ...
0
votes
3answers
359 views

Xna Equivalent of Viewport.Unproject in a draw call as a matrix transformation

I am making a 2D sidescroller and I would like to draw my sprite to world space instead of client space so I do not have to lock it to the center of the screen and when the camera stops the sprite ...
2
votes
2answers
415 views

Passing an objects rotation down through its children

In my topdown 2d game you have a player with a sword, like an old Zelda game. The sword is a seperate entity, and its collision box "rotates" around the player like an orbit, but always follows the ...
8
votes
1answer
1k views

Screen space to world space

I am writing a 2D game where my game world has x axis running left to right, y axis running top to bottom, and z axis out of the screen: Whilst my game world is top-down, the game is rendered on a ...
1
vote
2answers
597 views

Transformation order when dealing with Meshes

I have created a player model out of primitive types. To do this I have created a Model class and Component (mesh) class. Each model consists of one or more components my problems start when you have ...
1
vote
1answer
286 views

How to prevent 2D camera rotation if it would violate the bounds of the camera?

I'm working on a Camera class and I have a rectangle field named Bounds that determines the bounds of the camera. I have it working for zooming and moving the camera so that the camera cannot exit its ...
2
votes
2answers
616 views

What is the difference between Vector2.Transform and this method?

I've been working on some steering behaviors and ran into trouble with my logic for converting points in world space into points in local space. I had this (it's not optimized for multiple points yet, ...
2
votes
1answer
258 views

How do you extract a Vector3 positions only from a world matrix in an array of positions (from Kinect)

've just started building a physical camera class for the depth data you get from a Kinect. I have a Vector3 array of [imageWidth, imageHeight] describing the LOCAL positions I get in from the kinect ...
2
votes
1answer
315 views

Confused about order of operation when using a Matrix in XNA, C#

Here are two different pieces of code This is what I started with Vector2 hold = Vector2.Transform(pos1, mat1); Matrix inv = Matrix.Invert(mat2); Vector2 pos2 = Vector2.Transform(hold, inv); And ...
2
votes
1answer
705 views

How can I use a 3x3 matrix within a 4x4 matrix representation?

In XNA there is only one Matrix class which is actually 4x4 matrix. How to use it to represent a 3x3 matrix? I am trying to represent the inertia tensor of a body which is a 3x3 matrix, so I have ...
2
votes
1answer
373 views

Transformed Pretransformed coordinates?

I am creating a minecraft like terrain engine thing in XNA and C#, and I am trying to create a item/block selector tool. The thing is I would like to have 3D objects on the tool. So I thought for the ...
7
votes
3answers
980 views

How do I adjust the origin of rotation for a group of sprites?

I am currently grouping sprites together, then applying a rotation transformation on draw: private void UpdateMatrix(ref Vector2 origin, float radians) { Vector3 matrixorigin = new ...
6
votes
3answers
663 views

Why is my model's scale changing after rotating it?

I have just started a simple flight simulator and have implemented Roll and pitch. In the beginning, testing went very well; however, after about 15-20 seconds of constantly moving the thumbsticks in ...
2
votes
2answers
959 views

How should I calculate world and projection matrices in this scenario?

I'm trying to understand transformation matrices. Suppose I use the camera from this StackOverflow answer, this is how my view matrix would look: Matrix.Identity * ...
5
votes
3answers
1k views

XNA 4.0: 2D Camera Y and X are going in wrong direction

I asked this question on stackoverflow but assumed this might be a better area to ask it as well for a more informed answer. My problem is that I am trying to create a camera class and have it so ...
1
vote
1answer
633 views

XNA 2D Transform Matrix Scale at Zoom Question

This is the complete code I am currently using for my camera. It is incomplete and only partially understood by me (I am working off an example), but I have managed to hack some functionality with ...
2
votes
2answers
835 views

How do I calculate an offset from an Object based on the Objects Rotation rather than the World Space

I have a Matrix of a player & I want to create a second location a set distance away from the first location but I want the second matrix to be set a set distance based on the rotation of the ...
4
votes
4answers
919 views

From camera coordinates to world coordinates

I want to calculate world coordinates from camera coordinates. However, I seem to have problems with my understandings of how matrices in HLSL work. From world to camera is clear: cameraPosition = ...
2
votes
3answers
869 views

Interpolating Matrices

Apologies if I am missing something very obvious (likely!) but is there anything wrong with interpolating between two matrices by: float d = (float)(targetTime.Ticks - keyframe_start.ticks) / ...