mirror of https://github.com/GNOME/gimp.git
126 lines
3.8 KiB
C
126 lines
3.8 KiB
C
/***************************************************************************/
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/* GCK - The General Convenience Kit. Generally useful conveniece routines */
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/* for GIMP plug-in writers and users of the GDK/GTK libraries. */
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/* Copyright (C) 1996 Tom Bech */
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/* */
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/* This program is free software; you can redistribute it and/or modify */
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/* it under the terms of the GNU General Public License as published by */
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/* the Free Software Foundation; either version 2 of the License, or */
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/* (at your option) any later version. */
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/* */
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/* This program is distributed in the hope that it will be useful, */
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/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
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/* GNU General Public License for more details. */
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/* */
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/* You should have received a copy of the GNU General Public License */
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/* along with this program; if not, write to the Free Software */
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/* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, */
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/* USA. */
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/***************************************************************************/
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/***************************/
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/* Misc. useful math stuff */
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/***************************/
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#include <math.h>
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#include <gck.h>
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double gck_deg_to_rad(double angle)
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{
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return((angle/360.0)*(2.0*M_PI));
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}
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double gck_rad_to_deg(double angle)
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{
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return((angle/(2.0*M_PI))*360.0);
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}
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void gck_mat_to_deg(double mat[4][4],double *a,double *b,double *c)
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{
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*a=180*(asin(mat[1][0])/M_PI_2);
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*b=180*(asin(mat[2][0])/M_PI_2);
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*c=180*(asin(mat[2][1])/M_PI_2);
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}
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/*************************************************/
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/* Quick and dirty (and slow) line clip routine. */
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/* The function returns FALSE if the line isn't */
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/* visible according to the limits given. */
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/*************************************************/
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int gck_clip_line(double *x1,double *y1,double *x2,double *y2,
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double minx,double miny,double maxx,double maxy)
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{
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double tmp;
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g_function_enter("gck_clip_line");
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g_assert(x1!=NULL);
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g_assert(y1!=NULL);
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g_assert(x2!=NULL);
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g_assert(y2!=NULL);
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/* First, check if line is visible at all */
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/* ====================================== */
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if (*x1<minx && *x2<minx) return(FALSE);
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if (*x1>maxx && *x2>maxx) return(FALSE);
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if (*y1<miny && *y2<miny) return(FALSE);
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if (*y1>maxy && *y2>maxy) return(FALSE);
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/* Check for intersection with the four edges. Sort on x first. */
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/* ============================================================ */
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if (*x2<*x1)
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{
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tmp=*x1;
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*x1=*x2;
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*x2=tmp;
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tmp=*y1;
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*y1=*y2;
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*y2=tmp;
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}
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if (*x1<minx)
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{
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if (*y1<*y2) *y1=*y1+(minx-*x1)*((*y2-*y1)/(*x2-*x1));
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else *y1=*y1-(minx-*x1)*((*y1-*y2)/(*x2-*x1));
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*x1=minx;
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}
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if (*x2>maxx)
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{
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if (*y1<*y2) *y2=*y2-(*x2-maxx)*((*y2-*y1)/(*x2-*x1));
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else *y2=*y2+(*x2-maxx)*((*y1-*y2)/(*x2-*x1));
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*x2=maxx;
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}
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if (*y1<miny)
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{
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*x1=*x1+(miny-*y1)*((*x2-*x1)/(*y2-*y1));
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*y1=miny;
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}
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if (*y2<miny)
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{
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*x2=*x2-(miny-*y2)*((*x2-*x1)/(*y1-*y2));
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*y2=miny;
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}
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if (*y1>maxy)
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{
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*x1=*x1+(*y1-maxy)*((*x2-*x1)/(*y1-*y2));
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*y1=maxy;
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}
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if (*y2>maxy)
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{
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*x2=*x2-(*y2-maxy)*((*x2-*x1)/(*y2-*y1));
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*y2=maxy;
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}
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g_function_leave("gck_clip_line");
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return(TRUE);
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}
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