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Type: Posts; User: MichaelA

1. ## Thread: Inverse Orthogonal Matrix

by MichaelA
Replies
6
Views
2,700

### Re: Inverse Orthogonal Matrix

Yes the matrix is orthonormal, I get those terms confused. I do not use scaling at all.
I cannot thank you enough for this information, I knew it was possible, I studied matrices in Linear Algebra,...
2. ## Thread: Inverse Orthogonal Matrix

by MichaelA
Replies
6
Views
2,700

### Re: Inverse Orthogonal Matrix

Thanks for your help, just one more question to clear it up for me a bit better.
So to get my inverse matrix, I separate the rotation and translation into their own matrices, transpose the rotation...

by MichaelA
Replies
6
Views
2,700

4. ## Thread: Inverse Orthogonal Matrix

by MichaelA
Replies
6
Views
2,700

### Re: Inverse Orthogonal Matrix

Just wanted to clarify:

If the first mat is M1 and its inverse, the second mat, is M1^-1 and I want to multiply M1^-1 by another matrix M2 to get the relative transform between M1 and M2, will I...
5. ## Thread: How do I code a spline path?

by MichaelA
Replies
1
Views
810

### Re: How do I code a spline path?

There is a lib called SGcore - there is a demo version available for download. It contains spline functions. Just keep in mind you need at least 3 points to define a spline using that lib.
6. ## Thread: Inverse Orthogonal Matrix

by MichaelA
Replies
6
Views
2,700

### Inverse Orthogonal Matrix

From what I understand (please correct if I'm wrong) if I have an orthogonal 4x4 matrix that contains no scaling and only rotation and translation, I can obtain the inverse matrix by transposing the...
7. ## Thread: How to remove material from Solids?

by MichaelA
Replies
3
Views
1,131

### Re: How to remove material from Solids?

For anyone who is interested, after an exhaustive web search, I found a most useful solids modelling library that works with OpenGL and I am sure other rendering engines. sgCore by Geometros.
I...
8. ## Thread: How to remove material from Solids?

by MichaelA
Replies
3
Views
1,131

### Re: How to remove material from Solids?

Thanks, CSG has now been added to my search terms.
Cheers!
9. ## Thread: How to remove material from Solids?

by MichaelA
Replies
3
Views
1,131

### How to remove material from Solids?

I have been given a project to work on that renders an object after it has intersected with another object, i.e one object "removes material" from another object. For instance, a drill enters a piece...
10. ## Thread: [SOLVED] How to swap Y and Z axes in a matrix?

by MichaelA
Replies
2
Views
2,551

### Re: [SOLVED] How to swap Y and Z axes in a matrix?

I forgot to add that your x-axis will be reversed after the second rotation.
11. ## Thread: [SOLVED] How to swap Y and Z axes in a matrix?

by MichaelA
Replies
2
Views
2,551

### Re: [SOLVED] How to swap Y and Z axes in a matrix?

You would rotate around the x-axis exactly positive 90 degrees (pi/2 radians), the positive z-axis will now be where the positive y-axis was, but the negative y-axis will be where the positive z-axis...

by MichaelA
Replies
5
Views
1,902

### Re: Matrix Rotations

I would like to help with this. Can you provide the actual code you are using inside your Multiply function, and also the snippet of code that surrounds the function call? I would like to see how...

by MichaelA
Replies
5
Views
1,955

### Re: Acceleration Problem

Thanks very much for your help with this everyone. I had a feeling I was going to run into a problem with this.

Just to give a better idea about what I'm trying to do, my application is a machine...

by MichaelA
Replies
5
Views
1,955

### Acceleration Problem

Hello again everyone,

I have worked out an acceleration profile for a special motion application that ends up looking like this:

d = (t + sin t)/2

(I took the integral of (1 - cos t)/2) so...
15. ## Thread: Rotation Parallel to Vector

by MichaelA
Replies
12
Views
4,052

### Re: Rotation Parallel to Vector

OK, we started with this

float az = atan2 (dy, dx) * RADDEG;
float el = asin (dz / length ) * RADDEG;

glPushMatrix ();
glRotatef ( az, 0,0,1);
glRotatef...
16. ## Thread: Rotation Parallel to Vector

by MichaelA
Replies
12
Views
4,052

### Re: Rotation Parallel to Vector

Thanks very much! I understand, I will put it to good use very soon.

Thanks again,
Mike
17. ## Thread: Rotation Parallel to Vector

by MichaelA
Replies
12
Views
4,052

### Re: Rotation Parallel to Vector

I think the problem is related to my original question. I want to draw a gluCylinder, which defaults to being drawn with its height along the Z-axis starting at the origin. Sorry, I forgot to...
18. ## Thread: Rotation Parallel to Vector

by MichaelA
Replies
12
Views
4,052

### Re: Rotation Parallel to Vector

MaxH,

Thanks very much, I am going to try both your method and the one suggested by KjuEnnDee and see how it goes.

My WorldUp vector is Z so I will modify accordingly. It took me a few...
19. ## Thread: Rotation Parallel to Vector

by MichaelA
Replies
12
Views
4,052

### Re: Rotation Parallel to Vector

So are you saying I build my own rotation matrix and then load that into the MODELVIEW matrix?

If so then I will try the math approach you suggested.
...
20. ## Thread: Rotation Parallel to Vector

by MichaelA
Replies
12
Views
4,052

### Rotation Parallel to Vector

Hi everyone. The problem is as follows:

I have a line drawn between two vertices and I would like to rotate a gluCylinder so that it is pointing in the same direction (parallel to the line).
I...
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