/* tristrip.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"

#define WIN_GEOM	"500x500+50+50"

/* Structure ID */
static PEXStructure	struct_id;

/* Miscellaneous constants we use. */
#define NUM_TRIANGLES		21
#define NUM_VERTICES		(NUM_TRIANGLES + 2)
#define X_START			0.2
#define X_END			0.8
#define Y0			0.7
#define Z0			0.5
#define STRIP_HALF_WIDTH	0.15
#define TWIST_ANGLE		M_PI

static void
create_structure( dpy )
    Display	*dpy;
{
    PEXColor		color;
    PEXCoord		vertices[NUM_VERTICES];
    PEXVertexRGB	vertices_with_color[NUM_VERTICES];
    PEXArrayOfVertex	verts;
    PEXArrayOfFacetData dummy;
    unsigned int	i, facet_data_flag, vertex_data_flag;
    double		dx, delta, angle;
    
    /* Generate the points for the band. */
    dx = (X_END - X_START) / (NUM_VERTICES - 1);
    delta = TWIST_ANGLE / (NUM_VERTICES - 1);

    /* The top vertices. */
    for ( i = 0; i < NUM_VERTICES; i += 2 ) {
	vertices[i].x = X_START + i * dx;
	angle = i * delta;
	/* Compute the vertices for the hollow strip. */
	vertices[i].y = Y0 + STRIP_HALF_WIDTH * cos( angle );
	vertices[i].z = Z0 + STRIP_HALF_WIDTH * sin( angle );

	/* Set the coordinates and colors for the shaded strip. */
	vertices_with_color[i].point = vertices[i];
	vertices_with_color[i].point.y -= 0.4;
	vertices_with_color[i].rgb.red = 1.0;
	vertices_with_color[i].rgb.green = 0.0;
	vertices_with_color[i].rgb.blue = 0.0;
    }

    /* The bottom vertices. */
    for ( i = 1; i < NUM_VERTICES; i += 2 ) {
	vertices[i].x = X_START + i * dx;
	angle = i * delta;
	/* Compute the vertices for the hollow strip. */
	vertices[i].y = Y0 - STRIP_HALF_WIDTH * cos( angle );
	vertices[i].z = Z0 - STRIP_HALF_WIDTH * sin( angle );

	/* Set the coordinates and colors for the shaded strip. */
	vertices_with_color[i].point = vertices[i];
	vertices_with_color[i].point.y -= 0.4;
	vertices_with_color[i].rgb.red = 1.0;
	vertices_with_color[i].rgb.green = 1.0;
	vertices_with_color[i].rgb.blue = 1.0;
    }

    /* Make the ends of the band square. */
    vertices[1].x = X_START;
    vertices[NUM_VERTICES - 2].x = vertices[NUM_VERTICES - 1].x;
    vertices_with_color[1].point.x = X_START;
    vertices_with_color[NUM_VERTICES - 2].point.x
	= vertices[NUM_VERTICES - 1].x;
    
    /* Create the structure. */
    struct_id = PEXCreateStructure( dpy );
    
    /* Set the interior style and color. */
    PEXSetInteriorStyle( dpy, struct_id, PEXOCStore,
			 PEXInteriorStyleHollow );
    SET_COLOR( 1, 1, 1, color ); /* white */
    PEXSetSurfaceColor( dpy, struct_id, PEXOCStore,
		        PEXColorTypeRGB, &color );
    
    /* Distinguish between front and back faces. */
    PEXSetFacetDistinguishFlag( dpy, struct_id, PEXOCStore, True );

    /* Set the back interior style and color. */
    PEXSetBFInteriorStyle( dpy, struct_id, PEXOCStore,
			   PEXInteriorStyleHollow );
    SET_COLOR( 1, 1, 0, color ); /* yellow */
    PEXSetBFSurfaceColor( dpy, struct_id, PEXOCStore,
			  PEXColorTypeRGB, &color );
    
    /* Create the hollow triangle strip. */
    facet_data_flag = PEXGANone;
    vertex_data_flag = PEXGANone;
    verts.no_data = vertices;
    PEXTriangleStrip( dpy, struct_id, PEXOCStore,
		      facet_data_flag, vertex_data_flag,
		      PEXColorTypeRGB, dummy,
		      NUM_VERTICES, verts );
	
    /* Set the attributes for the shaded strip. */
    PEXSetInteriorStyle( dpy, struct_id, PEXOCStore,
			   PEXInteriorStyleSolid );
    PEXSetSurfaceInterpMethod( dpy, struct_id, PEXOCStore,
			       PEXSurfaceInterpColor );
    
    /* Stop distinguishing between front and back faces. */
    PEXSetFacetDistinguishFlag( dpy, struct_id, PEXOCStore, False );

    /* Create the shaded triangle strip. */
    vertex_data_flag = PEXGAColor;
    verts.rgb = vertices_with_color;
    PEXTriangleStrip( dpy, struct_id, PEXOCStore,
		      facet_data_flag, vertex_data_flag,
		      PEXColorTypeRGB, dummy,
		      NUM_VERTICES, verts );
}

static void
redraw( dpy, window, renderer )
    Display	*dpy;
    Window	window;
    PEXRenderer	renderer;
{
    XClearWindow( dpy, window );
    PEXRenderNetwork( dpy, window, renderer, struct_id );
    XFlush( dpy );
}

main( argc, argv )
    int		argc;
    char	*argv[];
{
    Display			*dpy;
    Window			window;
    XEvent			event;
    XVisualInfo			vis_info;
    XColor			bkgd_color;
    XStandardColormap		cmap_info;
    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 );
    
    /* Create the structure and Set up the PEX renderer. */
    if ( STRUCTURE_SPT( pexinfo ) ) {
	create_structure( dpy );
	renderer = ora_setup_renderer( dpy, window, &capx_info,
				       &rattrs );
    } else {
	fprintf( stderr, "Structures not supported.\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;
}