#include <global.h>

Data Structures
struct	line_and_slope
Typedefs
typedef struct line_and_slope	line_and_slope
Functions
static void	determine_line (line_and_slope *dest, int sx, int sy, int ex, int ey)
int	add_color_to_surface (SDL_Surface *dest, Uint8 red, Uint8 green, Uint8 blue)
int	copy_pixel_to_pixel (SDL_Surface src, SDL_Surface dest, int x, int y, int x2, int y2, float brightness)
int	copy_vertical_line (SDL_Surface src, SDL_Surface dest, int src_x, int src_sy, int src_ey, int dest_x, int dest_sy, int dest_ey, float brightness, int extra)
SDL_Surface *	tile_stretch (SDL_Surface *src, int n, int e, int s, int w)
Variables
static int	std_tile_half_len []

Detailed Description

Tile stretching routines.

Tile stretching stretches all floor tiles and modifies y position of all other layer objects, for example, floor tile with "z 4" would be stretched, and all objects above it would have z increased by 4. Layer 2 objects are also stretched.

align_tile_stretch() calculates how much to stretch each tile in all 4 directions based on the surrounding tiles.

Todo:

Support for negative z (so surrounding tiles can have "z 0", and the middle one "z 4" to make it look like a hole, for example).

Most fmasks (grass, for example) are not properly stretched.

Author:: James "JLittle" Little; Documentation by: Karon Webb

Definition in file tilestretcher.c.

Typedef Documentation

typedef struct line_and_slope line_and_slope

Line information structure.

Function Documentation

int add_color_to_surface	(	SDL_Surface *	dest,
		Uint8	red,
		Uint8	green,
		Uint8	blue
	)

Adds a colour to the palette in a bitmap ("surface").

Definition at line 157 of file tilestretcher.c.

int copy_pixel_to_pixel	(	SDL_Surface *	src,
		SDL_Surface *	dest,
		int	x,
		int	y,
		int	x2,
		int	y2,
		float	brightness
	)

Copy a pixel from a source pixel map's co-ordinates to a target pixel map's co-ordinates, adjusting the pixel's brightness.

Pseudo-code:

   PIXEL(dest, x2, y2) = AdjustPixelBrightness(PIXEL(src, x1, y1), brightness)

Note:: The pixel colour is added to the palette in the destination bitmap if necessary.

Warning:: brightness above 1.0 is (apparently) allowed but brightness < 0 is not tested and could cause problems.

Definition at line 193 of file tilestretcher.c.

int copy_vertical_line	(	SDL_Surface *	src,
		SDL_Surface *	dest,
		int	src_x,
		int	src_sy,
		int	src_ey,
		int	dest_x,
		int	dest_sy,
		int	dest_ey,
		float	brightness,
		int	extra
	)

Copy a vertical line from a source pixel map's co-ordinates to a target pixel map's co-ordinates, adjusting all the pixels' brightness.

This also applies a transmutation, "stretching" or "shrinking the line as appropriate:

If the target is twice the length it will receive pairs of pixels from the source, and if half the length every other pixel.

brightness applies to all pixels: above 1.0 is (apparently) allowed but brightness < 0 is not tested and could cause problems.

Set extra non-zero to duplicate the top pixel if the target line height is shorter than the source.

Note:: To allow for rounding, it is recommended to set extra unless the target line is the same length or shorter.; There is no "smoothing" or "averaging" done at all - the result could benefit hugely by adding logic to do things like that.; This function would be horribly inefficient if ever used to shrink a long line down to a few pixels.

Definition at line 277 of file tilestretcher.c.

static void determine_line	(	line_and_slope *	dest,
		int	sx,
		int	sy,
		int	ex,
		int	ey
	)		`[static]`

Calculate line information given its start and end co-ordinates.

This populates a line_and_slope structure.

Parameters:

dest	What line information structure to populate.
sx	Starting X.
sy	Starting Y.
ex	Ending X.
ey	Ending Y. *

Definition at line 117 of file tilestretcher.c.

SDL_Surface* tile_stretch	(	SDL_Surface *	src,
		int	n,
		int	e,
		int	s,
		int	w
	)

Generates the bitmap ("surface") for displaying a tile after stretching.

Stretching takes place from the horizontal centre, so from a "standard" viewpoint (i.e. some distance away from the viewed object), horizontal stretching should be done with either e or w <= 0 and the other > 0 (the part of the object appearing the original size centres on the zero).

Their absolute difference controls the brightness of the edges, so at the moment a horizontal line of horizontally stretched objects will appear to have vertical "bars" - especially as the underlying pixel stretching only occurs vertically (i.e. the measured "width" doesn't change).

Recommended limit is that neither e nor w exceed n+9. Major problems may occur if the total horizontal stretching (i.e. ABS(e - w)) exceeds 25.

Parameter documentation repeated in the body:

In the isometric view, closer objects are displayed lower down
on the VDU (smaller y co-ordinate) and further objects are displayed higher up (larger y co-ordinate).
The SW corner moves closer the more West the tile is stretched.
The NE corner moves closer the more East the tile is stretched.
Both the SW and NE corners move further away the more North the tile is stretched.
Both the SE and NW corners move close the more South and further away the more North the tile is stretched

Definition at line 387 of file tilestretcher.c.

Variable Documentation

int std_tile_half_len[] [static]

Initial value:

{
    0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
    10, 10, 11, 11, 11, 11, 10, 10, 9, 9, 8, 8, 7, 7, 6, 6, 5,
    5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0
}

Pixel y-co-ordinate (offset) of the edge of a standard (i.e. un-stretched) tile for each x co-ordinate pixel. In our isometric view the displayed "depth" is half the width. The tile pixels then form a rhombus on the VDU:

                        //\\
  ^                   //    \\
  |                 //        \\
  y               //            \\
          W     //                \\    N
              //                    \\
            //                        \\
          //                            \\
        //                                \\
      //                                    \\
    //                                        \\
  //                                            \\
  \\                                            //
    \\                                        //
      \\                                    //
        \\                                //
          \\                            //
            \\                        //
              \\                    //
          S     \\                //    E
                  \\            //
                    \\        //
  |                   \\    //
  + -                   \\//                x - >

Definition at line 79 of file tilestretcher.c.

Data Structures

Typedefs

Functions

Variables

Detailed Description

Typedef Documentation

Function Documentation

Variable Documentation