[gameprogrammer] Re: RES: Re: RES: RES: Re: RES: Re: DirectX Line and Triangle
- From: "Alan Wolfe" <alan.wolfe@xxxxxxxxx>
- To: gameprogrammer@xxxxxxxxxxxxx
- Date: Tue, 15 Jul 2008 16:28:53 -0700
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&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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>
>
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> 06:49
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