Login
Username:

Password:

Remember me



Lost Password?

Register now!

Sections

Who's Online
59 user(s) are online (43 user(s) are browsing Forums)

Members: 0
Guests: 59

more...

Support us!
Donate

Headlines
Recent files - OS4Depot - Your one stop for AmigaOS4 files

 
Jump to the bottom of the page Bottom    View previous topic Previous Topic    View next topic Next Topic

  Register To Post  

elfpipe
Trapezoids??
Posted on: 2012/3/15 20:23    #1
Just can't stay away
Just can't stay away


See User information
The Qt X11 renderer uses trapezoids to render with XRenderCompositeTrapezoids. I am trying to use the code to render with CompositeTags, but all I get is this mishmash of triangles.

XRender defines a trapezoid as

{
A,B,C,D
top, bottom
}

...where A,B,C and D are points (x,y) and top and bottom are floats.

Now my question is this: What role does the top and bottom values play?? As far as I can see, it is enough with four points to define a trapezoid, so why are the top and bottom values needed??
Go to top
broadblues
Re: Trapezoids??
Posted on: 2012/3/15 22:10    #2
Home away from home
Home away from home


See User information
I found

typedef struct _XTrapezoid {
            XFixed  top, bottom;
            XLineFixed  left, right;
        } XTrapezoid;


where

typedef struct _XPointFixed {
            XFixed  x, y;
        } XPointFixed;

        typedef struct _XLineFixed {
            XPointFixed p1, p2;
        } XLineFixed;


This from :
http://www.x.org/archive/X11R7.5/doc/libXrender/libXrender.txt

Is your information correct?
Blender For OS4.x : Blues : Walker Broad
Go to top
elfpipe
Re: Trapezoids??
Posted on: 2012/3/16 15:46    #3
Just can't stay away
Just can't stay away


See User information
@broadblues

Yes, that's the information I have. Eg. they use fixed point and not floating point, but apart from that I think my description fits.

I might have to write my own triangulator, which is dull, but I would rather that than have to invoke the glu triangulator (trying to get rid of opengl alltogether).
Go to top
Gazelle
Re: Trapezoids??
Posted on: 2012/3/17 9:53    #4
Just popping in
Just popping in


See User information
@alfkil

from renderproto.txt (Trapezoids)
Quote:
[...] For each trap, the area between the left and right edges is filled from the top to the bottom. [...]


So my guess would be they are some sort of limitation for the fill operation?
Go to top
elfpipe
Re: Trapezoids??
Posted on: 2012/3/17 15:47    #5
Just can't stay away
Just can't stay away


See User information
@Gazelle

Yes, I think that is it. Managed to make it work with some copy/pasted code from the OpenGL triangulator .
Go to top
spotUP
Re: Trapezoids??
Posted on: 2012/3/17 15:52    #6
Just can't stay away
Just can't stay away


See User information
Alfkil: yeah!
Go to top

  Register To Post

 
Jump to the top of the page Top    View previous topic Previous Topic    View next topic Next Topic




Currently Active Users Viewing This Thread: 1 ( 0 members and 1 Anonymous Users )



Polls
Running AmigaOS 4 on?
AmigaOne SE/XE or microA1 12% (26)
Pegasos2 3% (8)
X5000 22% (48)
X1000 14% (30)
A1222 8% (19)
Sam 440/460 18% (40)
Classic PowerPC Amiga 2% (6)
WinUAE emulation 7% (16)
Qemu emulation 9% (21)
Total Votes: 214
The poll closed at 2025/12/1 12:00
6 Comments


Powered by XOOPS 2.0 © 2001-2024 The XOOPS Project