[gameprogrammer] RES: Re: RES: Re: RES: RES: Re: RES: Re: DirectX Line and Triangle
- From: "Edilson Vasconcelos de Melo Junior" <dirso@xxxxxxxxxxxxxxxxxx>
- To: <gameprogrammer@xxxxxxxxxxxxx>
- Date: Mon, 21 Jul 2008 16:44:15 -0300
Thank you very much for your help!!! It took me a while until a figure out
that the problem was totally about the 2d solution is not totally effective.
If anyone is interested, I?m showing my solution, based on Alan?s.
1) Find the 3d segment line (AB) middle point (M)
2) Normalize AB and call it DIR1
3) CrossProduct DIR1 and NEGATIVE_Y (0,-1,0), creating a VEC1 vector
and normalize it.
4) CrossProduct DIR1 and NEGATIVE_Z (0,0,-1), creating a VEC2 vector
and normalize it.
5) CrossProduct DIR1 and NEGATIVE_X (-1,0,0), creating a VEC3 vector
and normalize it.
6) Create a Vector3 point downVertex = M - DIR1*TriangleLength)/2.0f)
7) Create a Vector3 point upVertex = M + DIR1*TriangleLength)/2.0f)
8) We?ll make 3 triangles to be sure we have a visible arrow no matter
what the line inclination
a. Triangle1 = (VEC1*TriangleWidth + downVertex, upVertex,
-VEC1*TriangleWidth + downVertex)
b. Triangle2 = (VEC1*TriangleWidth + downVertex, upVertex,
-VEC2*TriangleWidth + downVertex)
c. Triangle3 = (VEC1*TriangleWidth + downVertex, upVertex,
-VEC3*TriangleWidth + downVertex)
It becomes a good looking screen.
Thanks again,
Dirso
De: gameprogrammer-bounce@xxxxxxxxxxxxx
[mailto:gameprogrammer-bounce@xxxxxxxxxxxxx] Em nome de Alan Wolfe
Enviada em: terça-feira, 15 de julho de 2008 20:29
Para: gameprogrammer@xxxxxxxxxxxxx
Assunto: [gameprogrammer] Re: RES: Re: RES: RES: Re: RES: Re: DirectX Line
and Triangle
drunken hyena is good, i am also a fan :P
there's a great book "introduction to 3d game programming with directx 9.0"
written by Frank D Luna too:
http://www.amazon.com/Introduction-Programming-DirectX-Wordware-Graphics/dp/
1556229135/ref=pd_bbs_sr_2?ie=UTF8
<http://www.amazon.com/Introduction-Programming-DirectX-Wordware-Graphics/dp
/1556229135/ref=pd_bbs_sr_2?ie=UTF8&s=books&qid=1216164488&sr=8-2>
&s=books&qid=1216164488&sr=8-2
good luck!
On 7/15/08, Edilson Vasconcelos de Melo Junior <dirso@xxxxxxxxxxxxxxxxxx>
wrote:
Thank you so much!!! It looks an amazing idea. I have not used DirectX in
the past and I think my Ogre3D experience is not helping me much. The best
tutorial I found for this is
http://www.drunkenhyena.com/pages/projects/d3d8/d3d_lesson5.php Do you know
anything better (and still quick)? I'll try to port this code to my C# appl,
how hard can it be J?
Thanks again for your help,
Dirso
De: gameprogrammer-bounce@xxxxxxxxxxxxx
[mailto:gameprogrammer-bounce@xxxxxxxxxxxxx] Em nome de Alan Wolfe
Enviada em: terça-feira, 15 de julho de 2008 14:10
Para: gameprogrammer@xxxxxxxxxxxxx
Assunto: [gameprogrammer] Re: RES: RES: Re: RES: Re: DirectX Line and
Triangle
Well in your case i think going w/ a pyramid might be easier because if you
use a flat triangle you might want to make it billboarded (or partially
billboarded) where it is always perpendicular to how the person is looking
at it which involves a lot more math!
Since you are in 3d and not 2d what you might have better luck with is
making a pyramid "model" that has a center of 0,0 and is pointing to the
right (like you would see on a regular horizontal line).
Then what you do is when you want to render one of these pyramids on a line,
you calculate how much you should rotate the pyramid on the Y and Z axis to
point along the line (by finding the angles of the line), then render the
pyramid rotated that amount at the midpoint of the line.
you could store this pyramid in a vertex buffer if you wanted to and it
should render really quickly.
You could also make these pyramids rotate on the X axis over time so that
they were slowly spinning when the player was looking at them which might be
a cool effect for your purposes (:
to calculate how much to rotate the pyramid you are going to have to use
something like arc tangent (make sure and use atan2 instead of atan, check
the docs on those to find out why).
On 7/14/08, Edilson Vasconcelos de Melo Junior <dirso@xxxxxxxxxxxxxxxxxx>
wrote:
BTW: The flat triangle was just an idea. It could be a cone or a pyramid or
anything else that could indicate the driving way. Anything easy and of
course that DirectX could draw 5,000 on screen without drastically reducing
de frame rate.
Thanks,
Dirso
De: gameprogrammer-bounce@xxxxxxxxxxxxx
[mailto:gameprogrammer-bounce@xxxxxxxxxxxxx] Em nome de Edilson Vasconcelos
de Melo Junior
Enviada em: segunda-feira, 14 de julho de 2008 20:41
Para: gameprogrammer@xxxxxxxxxxxxx
Assunto: [gameprogrammer] RES: Re: RES: Re: DirectX Line and Triangle
The triangle is really a flat triangle, it's just something to indicate a
path. And the line segments do have x,y and z values. I work on this project
like google earth 3d client and my task is to draw lines representing
streets and make triangles over them pointing the allowed driving way.
Thanks,
Dirso
De: gameprogrammer-bounce@xxxxxxxxxxxxx
[mailto:gameprogrammer-bounce@xxxxxxxxxxxxx] Em nome de Alan Wolfe
Enviada em: segunda-feira, 14 de julho de 2008 19:22
Para: gameprogrammer@xxxxxxxxxxxxx
Assunto: [gameprogrammer] Re: RES: Re: DirectX Line and Triangle
the triangle you want to put on the lines, do you want it to be 3
dimensional (ie a pyramid, not a triangle?) or do you want it to just really
be a triangle.
also, when you say you are in 3d do you mean that your line segments all
have different X,Y and Z values? or are they all on the same Z value?
On 7/14/08, Edilson Vasconcelos de Melo Junior <dirso@xxxxxxxxxxxxxxxxxx>
wrote:
Hi,
I'm in 3d? can you help me a little more?
Thank you very much for your help,
Dirso
De: gameprogrammer-bounce@xxxxxxxxxxxxx
[mailto:gameprogrammer-bounce@xxxxxxxxxxxxx] Em nome de Alan Wolfe
Enviada em: segunda-feira, 14 de julho de 2008 17:38
Para: gameprogrammer@xxxxxxxxxxxxx
Assunto: [gameprogrammer] Re: DirectX Line and Triangle
Hey Dirso,
Here's a plan of attack (assuming you are in 2d)
Calculate the normal of the line segment to get a normalized vector
perpendicular to the line, this will be useful to figure out the vertices
for the flat back side of the triangle. Call this NX and NY.
Calculate the normalized vector of the line, call this LX and LY.
Find the midpoint of the line call this MX and MY.
Figure out how wide and how tall you want the triangle to be, call this
TWidth and THeight.
If you do the above, here's how to find each of the 3 vertices for the
triangle for each line:
Vertex 1:
*start at the midpoint
*subtract LX,LY multiplied by TWidth/2
*add NX,NY * THeight/2
Vertex 2:
*start at the midpoint
*add LX,LY * TWidth/2
Vertex 3:
*start at the midpoint
*subtract LX,LY multiplied by TWidth/2
*subtract NX,NY * THeight/2
That will give you the vertices in a clockwise order, so watch out for back
face culling if you have clockwise culled (:
On 7/14/08, Edilson Vasconcelos de Melo Junior <dirso@xxxxxxxxxxxxxxxxxx>
wrote:
Hi,
I have a CustomVertex.PositionColored[] object that represents a line and I
use the DrawUserPrimitives(PrimitiveType.LineStrip, this.linePoints.Length -
1, this.linePoints); to draw it on screen
Now I need to draw a small triangle aligned to each line segment and one of
each vertex must "pointy" to the finish point of the segment. How can I do
that?
Something like the attached picture, but not that ugly.
Thanks,
Dirso.
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