# Questions tagged [directxmath]

DirectXMath API provides common linear algebra and graphics math operations to DirectX applications

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### What's the relationship between the actor's pose and shape's pose in PhysX?

I have 2 Meshes and I want to add physics to them. The first is a primitive box, the second is a terrain. The box and terrain are made with DirectXMath Using the PhysX library, I made a copy of the ...
97 views

### What is wrong with my terrain lighting?

I've just implemented a simple algorithm to calculate terrain vertex normals and I'm using diffuse and ambient light currently, but for some reason the squares that make up my terrain are visible when ...
106 views

### Translate code to DIRECTX directxmath

How can i translate the code to directxmath code? ...
70 views

### XMMATRIX performance

Dears, I am facing a performance problem when I try to access cell 42 and 43 in XMMATRIX define in DirectXMath.h. The frames dropped by 100 FPS. Here is my code: ...
1k views

### What exactly does XMMatrixPerspective{L,R}H do?

There are generally three functions to create a perspective matrix in DirectXMath, XMMatrixPerspective{L,R}H, ...
2k views

### 2d Scale width and height based on distance

I'm drawing a health bar on top of each player. I transform 3d position to 2d. I would like to draw it smaller when distance increases. Any simple math for that? Let's say bar width is 30 and height ...
714 views

### Transforming quaternion between coordinate systems [duplicate]

Working in DirectX (with DirectXMath objects): If I have the rotation of an object relative to some coordinate space as quaternion Q, and I have a transformation matrix tx from that coordinate space ...
1 vote
124 views

### how to debug calculating tangent space

[][]2 there's problem calculating tangent space and look.... it seems there is no problem with UV code and my shader is 100% no problem. I just copy and pasted tutorial code which works well.. I ...
1 vote
701 views

### Why doesn't TriangleTests::Intersects from DirectXMath work correctly?

I am currently looking through the Introduction to 3D Game Programming with Direct X 11 by Frank Luna and I'm trying to implement the ray-triangle intersections. I already have a ray firing when the ...
303 views

### Is there something similar to XMFLOAT2 that has its operators overloaded?

Since XMFLOAT2 is just a structure, I'm sure it does not have operator overloading which is what I need to make things a lot simpler. Is there something like ...
137 views

### How to clip cut-off using different frustrum than that of original camera? How to cut plane by pyramid shape?

SOURCE : http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Mitchell_LightShafts.pdf This process is part of creating light draft effect. And I am suggested to do the described process in ...
1 vote
1k views

### Difference between column- and row vector matrix multiplication (vector transform)

Let's say we have a 4-by-4 matrix $A$ which represents some transformation. We can use this matrix to transform a vector in two ways. $Ax$ by assuming $x$ is a 4-by-1 column vector. $xA$ by ...
5k views

### Calculate matrix transformation components separately

It is possible to calculate the translation, rotation and scale that were used to build a matrix? I mean if I have a matrix M can I calculate the rotation, scale, ...
1 vote
2k views

### How to rotate camera using mouse?

I'm looking for a basic example of rotating camera using the mouse. the only problem is I'm not sure of how to rotating the camera around it target. should i do this by an algorithm or is there a ...
216 views

### How can I get projected coordinates of vertex on screen

I want to check picking for faces and for that I need projected X Y coordinates of my vertexes in -1 to 1 range: For that I multiply my vertex array with matrices and then get projected triangle ...
136 views

### Simulating aircraft movement with DirectX 9 [closed]

How would I go about simulating a planes movement in DirectX 9 using transforms (i.e. matrices). For example flying around an open space. When it moves it faces the direction it is going and ...
1 vote
2k views

### How do I correctly multiply an XMMATRIX by a scalar?

Using DirectXMath and its XMMATRIX structure in C++ and Direct X 11, how does one multiply that matrix structure by a single float scalar? I want to implement the ...
1 vote