Re: [Gimp-developer] Extrude-filter and lots of triangles
On Mon, 2 Aug 2004 05:39:09 + Markus Triska [EMAIL PROTECTED] wrote: Hello, a week or so ago, there was a request on comp.graphics.apps.gimp about the availability of the PS extrude-filter, used for example in this tutorial: Current version of the plug-in: http://stud4.tuwien.ac.at/~e0225855/extrude.c Horrible picture mentioned: http://stud4.tuwien.ac.at/~e0225855/extrude.png Hello, This was an interesting plug-in, the latest one more interesting than the first. Do you intend to have a user Dialogue interface for the plug-in? -- Owen ___ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Extrude-filter and lots of triangles
On Sunday 15 August 2004 12:56 am, you wrote: This was an interesting plug-in, the latest one more interesting than the first. Thank you, the current version produces even better results (all sides are now drawn in correct order). Do you intend to have a user Dialogue interface for the plug-in? Yes, now that I have got the basics somewhat right, the following parameters could be set/changed in a dialog: *) height of pyramids / random height? (boolean toggle) *) size of pyramids *) viewing distance *) direction of light vector (later: pyramids/blocks; don't hide partially visible objects) I still need to figure out useful default values for the settings (currently height = 80, size = 50, distance = 250, light vector = constantly changing to test the shading code, in the .c-file on the web it is (1,0,0), but need not be normalized). If you are interested in coding up (parts of) the dialog, just fetch the .c-file from the web and insert the code wherever you see fit, I can merge your changes later with my own latest version. The most appealing part of this task is probably the representation of the light vector - of course, 3 text-boxes each holding an integer would suffice (certainly for the initial version of the plug-in), but you may find an easy way to actually show and let users interactively edit the vector in pseudo-3D. Best regards, Markus. ___ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Extrude-filter and lots of triangles
On Monday 02 August 2004 11:20 pm, you wrote: Well, the quick-and-dirty way of doing it would be to select a triangle shape and use the GIMP's fill function. :) This is exactly what I want. For this I #include libgimp/gimpselection_pdb.h and #include libgimp/gimpedit_pdb.h Is there a drawback of this method or something else I should know (I found no core plug-in including a header ending _pdb.h, but I guess this is because none uses this)? I'm afraid I don't see why there is a lack of locality here: each triangle to be filled indeed has locality. Of course, if the triangle is sufficiently small, only one tile needs to be involved. Yes, each triangle has locality and of course, the whole effect also has locality (the drawable), but I meant locality with regards to tiles when using a tile iterator: I see no easy method to set up a tile iterator and iterate by some constant amount, because no matter how big I make that amount, there are always cases where triangles will cross a tile intersection. I did not look at the select and fill code, so I am not sure (especially wrt anti-aliasing) if a triangle started on tile A can be continued on tile B without visible jags. When I have the effect working, I will try such things, but it is not that important for now. Markus. ___ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Extrude-filter and lots of triangles
On Tuesday 03 August 2004 06:35 pm, Markus Triska wrote: This is exactly what I want. For this I #include libgimp/gimpselection_pdb.h and #include libgimp/gimpedit_pdb.h Can anybody beat this amount of stupidity? I just found out that these files are included via libgimp/gimp.h. Markus. ___ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Extrude-filter and lots of triangles
On Tuesday 03 August 2004 05:35 pm, Michael Schumacher wrote: May I suggest that you start from the gimp plug-in template? It help you to get e.g. the build configurations and the i18n of your plug-in right. Thank you for this suggestion. I have successfully used the plug-in template before and will add i18n and so on later. I currently work only on one single file (which can be conveniently compiled using gimptool), but as soon as I add Gtk UI code in a separate file, I will switch to using autotools. Markus. ___ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Extrude-filter and lots of triangles
Markus Triska wrote: On Tuesday 03 August 2004 06:35 pm, Markus Triska wrote: This is exactly what I want. For this I #include libgimp/gimpselection_pdb.h and #include libgimp/gimpedit_pdb.h Can anybody beat this amount of stupidity? I just found out that these files are included via libgimp/gimp.h. May I suggest that you start from the gimp plug-in template? It help you to get e.g. the build configurations and the i18n of your plug-in right. See http://developer.gimp.org for hints. HTH, Michael -- The GIMP http://www.gimp.org| IRC: irc://irc.gimp.org/gimp Wiki http://wiki.gimp.org | .de: http://gimpforum.de Sodipodi http://sodipodi.sf.net | IRC: irc://irc.gimp.org/sodipodi ___ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Extrude-filter and lots of triangles
Actually I would go about this differently: Start by making a list of all of the triangles, recording their vertices. Then go through the image, and for each pixel, figure out which triangle is visible there, and render its color. I think this would be a lot faster, and it lets you work with a tile iterator as well. If you start searching from the center of the image, and work outward, then the first triangle you find that overlies the point will be the one that is visible, so the search can be done pretty efficiently. In fact, there may even be a way of calculating which triangle is visible above a given pixel without having to do any searching. Best, -- Bill __ __ __ __ Sent via the KillerWebMail system at primate.ucdavis.edu ___ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Extrude-filter and lots of triangles
On Mon, 2 Aug 2004, Markus Triska wrote: I'm for now using a quick and terrible hack to fill the triangles (see attached source if you are curious) and want to ask: Which method do you recommend to fill lots of triangles from within a plug-in? Is there a (fast?) Gimp function for this that I can use, maybe capable of anti-aliasing? Well, the quick-and-dirty way of doing it would be to select a triangle shape and use the GIMP's fill function. :) I'm afraid I don't see why there is a lack of locality here: each triangle to be filled indeed has locality. Of course, if the triangle is sufficiently small, only one tile needs to be involved. Perhaps what you are really saying is that the tile cache needs to be really large to be effective because there is not much between-triangle locality. Rockwalrus ___ Gimp-developer mailing list [EMAIL PROTECTED] http://lists.xcf.berkeley.edu/mailman/listinfo/gimp-developer
[Gimp-developer] Extrude-filter and lots of triangles
Hello,
a week or so ago, there was a request on comp.graphics.apps.gimp about the
availability of the PS extrude-filter, used for example in this tutorial:
http://www.voidix.com/cystal.html
I spent a couple of hours working on a GIMP equivalent and I am attaching a
horrible sample picture created with the plug-in as it stands so far (it
currently uses random values for the colours of the pyramids and knows
nothing about anti-aliasing). I'm for now using a quick and terrible hack to
fill the triangles (see attached source if you are curious) and want to ask:
Which method do you recommend to fill lots of triangles from within a
plug-in? Is there a (fast?) Gimp function for this that I can use, maybe
capable of anti-aliasing?
I think there is no obvious way to use tile iterators for this effect (little
spatial locality), I am currently (g|s)etting the whole image at once - would
you recommend that I get and set a region for each triangle I draw or some
better compromise? I have not tried it yet - could it be too slow if there
are very many triangles, or slower than the swapping that could happen when
processing the whole image at once? I'm asking this because I could only
benchmark on my own system, which hardly is representative.
Best regards,
Markus.
External links:
Current version of the plug-in: http://stud4.tuwien.ac.at/~e0225855/extrude.c
Horrible picture mentioned: http://stud4.tuwien.ac.at/~e0225855/extrude.png
attachment: extrude.png/* The GIMP -- an image manipulation program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/* Plug-in (eventually) implementing Photoshop's Extrude effect
Written by Markus Triska [EMAIL PROTECTED]
August 2nd, 2004 - far from finished, just started working on it */
#include stdio.h
#include stdlib.h
#include libgimp/gimp.h
static void query (void);
static void run(const char*name,
gint nparams,
const GimpParam*param,
gint *nreturn_vals,
GimpParam **return_vals);
static void extrude_render (GimpDrawable *drawable);
struct MemImage {
long bpp;
guchar *data;
gint width, height, halfwidth, halfheight;
} theimage;
typedef struct pyramid_tag {
GimpVector3 triangles[4][3]; /* four triangles */
GimpRGB colours[4];
int order[4];
} Pyramid;
GimpPlugInInfo PLUG_IN_INFO =
{
NULL, /* init_proc */
NULL, /* quit_proc */
query, /* query_proc */
run, /* run_proc */
};
void
lines_intersection(GimpVector2 p1, GimpVector2 p2,
GimpVector2 p3, GimpVector2 p4,
GimpVector2 *intersectionpoint)
{
float a1,b1,c1, /* constants of linear equations */
a2,b2,c2,
det_inv, /* the inverse of the determinant of the coefficient */
m1,m2;/* the slopes of each line */
/* compute slopes, note the kludge for infinity, however, this will
be close enough */
if ((p2.x-p1.x)!=0)
m1 = (p2.y-p1.y)/(p2.x-p1.x);
else
m1 = (float)1e+10; /* close enough to infinity */
if ((p4.x-p3.x)!=0)
m2 = (p4.y-p3.y)/(p4.x-p3.x);
else
m2 = (float)1e+10; /* close enough to infinity */
/* compute constants */
a1 = m1;
a2 = m2;
b1 = -1;
b2 = -1;
c1 = (p1.y-m1*p1.x);
c2 = (p3.y-m2*p3.x);
/* compute the inverse of the determinant */
det_inv = 1/(a1*b2 - a2*b1);
/* use Cramer's rule to compute x and y */
intersectionpoint-x=((b1*c2 - b2*c1)*det_inv);
intersectionpoint-y=((a2*c1 - a1*c2)*det_inv);
}
static void
fill_triangle(struct MemImage memimg, GimpVector2 *points, GimpRGB rgb)
{
GimpVector2 tempvector,intersec1,intersec2;
gint curr_y, sortruns = 0;
if ((points[0].y == points[1].y) (points[1].y == points[2].y)) return;
/*
We enforce the following order on the points:
(a) non-decreasing y coordinates
(b) for y1 == y2, the point with lower x comes first
This leaves 4 types of triangles to handle:
0 10 0 0
/ \ /| |\
| / / \ 1 / | | \ 1
|/ |-\\ | | /
2 1 2 \|22|/
*/
GimpVector2 sortedpoints[3];
sortedpoints[0] = points[0]; sortedpoints[1] = points[1];
sortedpoints[2] = points[2];
for
