/* curves.c 1.1 */
/*
    Copyright 1992, 1993 O'Reilly and Associates, Inc.  Permission to
    use, copy, and modify this program is hereby granted, as long as
    this copyright notice appears in each copy of the program source
    code.
*/

#include "book_utils.h"

static void
redraw( dpy, window, renderer )
    Display	*dpy;
    Window	window;
    PEXRenderer	renderer;
{
    static PEXCoord 	control_points[] = {
	{.1,.8,0},{.35,.9,0},{.6,.9,0},{.4,.7,0},{.7,.7,0},{.9,.88,0}};
    static float	knots_2ord[] = {1,1,2,3,4,5,6,6};
    static float	knots_3ord[] = {1,1,1,2,3,4,5,5,5};
    static float	knots_6ord[] = {1,1,1,1,1,1,2,2,2,2,2,2};

    int			order, num_knots, i;
    unsigned int	num_points = 6;
    double		tmin, tmax;
    PEXArrayOfCoord	cpts;
    PEXColor		color;
    
    XClearWindow( dpy, window );
    PEXBeginRendering( dpy, window, renderer ); {
	SET_COLOR( 1, 1, 1, color );
	PEXSetLineColor( dpy, renderer, PEXOCRender,
			 PEXColorTypeRGB, &color );
	PEXSetMarkerColor( dpy, renderer, PEXOCRender,
			   PEXColorTypeRGB, &color );

	/* Assign the control-point list. */
	cpts.point = control_points;

	/* Second order curve. */
	order = 2;
	num_knots = sizeof(knots_2ord)/sizeof(knots_2ord[0]);
	tmin = knots_2ord[order-1];
	tmax = knots_2ord[num_knots - order];
	PEXNURBCurve( dpy, renderer, PEXOCRender, PEXNonRational,
		      order, knots_2ord, num_points, cpts, tmin, tmax );
	
	/* Use markers to show the control points. */
	PEXMarkers( dpy, renderer, PEXOCRender, 6, control_points );

	/* Set the approximation criteria for the other curves. */
	PEXSetCurveApprox( dpy, renderer, PEXOCRender,
			   PEXApproxConstantBetweenKnots, (double)20 );

	/* Third order curve. */
	order = 3;
	num_knots = sizeof(knots_3ord)/sizeof(knots_3ord[0]);
	tmin = knots_3ord[order-1];
	tmax = knots_3ord[num_knots - order];
	for ( i = 0; i < 6; i++ ) /* shift it down a bit */
	    control_points[i].y -= 0.3;
	PEXNURBCurve( dpy, renderer, PEXOCRender, PEXNonRational,
		      order, knots_3ord, num_points, cpts, tmin, tmax );
	PEXMarkers( dpy, renderer, PEXOCRender, 6, control_points );

	/* Sixth order curve. */
	order = 6;
	num_knots = sizeof(knots_6ord)/sizeof(knots_6ord[0]);
	tmin = knots_6ord[order-1];
	tmax = knots_6ord[num_knots - order];
	for ( i = 0; i < 6; i++ ) /* shift it down a bit */
	    control_points[i].y -= 0.3;
	PEXNURBCurve( dpy, renderer, PEXOCRender, PEXNonRational,
		      order, knots_6ord, num_points, cpts, tmin, tmax );
	PEXMarkers( dpy, renderer, PEXOCRender, 6, control_points );
    }
    PEXEndRendering( dpy, renderer, True );
    XFlush( dpy );
}

#define WIN_GEOM	"500x500+50+50"

main( argc, argv )
    int		argc;
    char	*argv[];
{
    Display			*dpy;
    Window			window;
    XEvent			event;
    XVisualInfo			vis_info;
    XStandardColormap		cmap_info;
    XColor			bkgd_color;
    PEXColorApproxEntry		capx_info;
    PEXRenderer			renderer;
    PEXRendererAttributes	rattrs;
    PEXExtensionInfo		*pexinfo;
    int				done = 0;
    
    /* Open a display and initialize PEX. */
    dpy = ora_init_pex( argv, &pexinfo );
    if ( !dpy ) exit(1);
    
    /* Determine the best visual to use. */
    ora_find_best_visual( dpy, &vis_info );
    
    /* Get a standard colormap for the visual. */
    if ( !ora_get_standard_colormap( dpy, &vis_info, &cmap_info ) ) {
	fprintf ( stderr, "Cannot find a standard colormap\n" );
	exit(1);
    }
    ora_set_stdcmap_approx( &vis_info, &cmap_info, &capx_info );

    /* Create the window, giving it a gray background. */
    bkgd_color.red = bkgd_color.green = bkgd_color.blue = 0x5555;
    bkgd_color.flags = DoRed | DoGreen | DoBlue;
    window = ora_create_window( dpy, &vis_info, &cmap_info, WIN_GEOM,
			        &bkgd_color );
    
    if ( IMMED_MODE_SPT( pexinfo ) ) {
	renderer = ora_setup_renderer( dpy, window, &capx_info,
				       &rattrs );
    } else {
	fprintf( stderr, "No immediate mode.\n" );
	exit(1);
    }
    
    /* Read and respond to X events. */
    XSelectInput( dpy, window, ExposureMask | ButtonPressMask );
    while ( !done ) {
	XNextEvent( dpy, &event );
	switch ( event.type ) {
	case Expose:
	    /* Flush remaining Expose events, then redraw. */
	    while ( XCheckTypedWindowEvent( dpy, window,
					    Expose, &event ) )
		; /* empty statement */
	    redraw( dpy, window, renderer );
	    break;
	case ButtonPress:
	    done = 1;
	    break;
	}
    }

    XCloseDisplay( dpy );
    return 0;
}