sprites.h

The <sprites.h> Header File

Simple sprite routines

Functions

ClipSprite8: Safely draws a sprite with a width of 8 pixels or less on the screen.
ClipSprite16: Safely draws a sprite with a width of 16 pixels or less on the screen.
ClipSprite32: Safely draws a sprite with a width of 32 pixels or less on the screen.
Sprite8: Draws a sprite with a width of 8 pixels or less on the screen.
Sprite16: Draws a sprite with a width of 16 pixels or less on the screen.
Sprite32: Draws a sprite with a width of 32 pixels or less on the screen.

Predefined Types

SprtModes: An enumeration to describe possible modes of sprite drawing.

For lots of advanced drawing routines, we recommend you to download either the ExtGraph static library by the TI-Chess Team or Genlib "kernel"-based dynamic library by the Time To Team.

ClipSprite8

void ClipSprite8 (short x, short y, short height, const unsigned char *sprite, void *vm_addr, short mode);

Safely draws a sprite with a width of 8 pixels or less on the screen.

ClipSprite8 works exactly like Sprite8, but it doesn't draw out of the boundaries of a 240x128 screen, unlike Sprite8 if given x < 0, y < 0, x > 232 or y > 128 - height.

See Sprite8 for more info about sprites.

ClipSprite16

void ClipSprite16 (short x, short y, short height, const unsigned short *sprite, void *vm_addr, short mode);

Safely draws a sprite with a width of 16 pixels or less on the screen.

ClipSprite16 works exactly like Sprite16, but it doesn't draw out of the boundaries of a 240x128 screen, unlike Sprite16 if given x < 0, y < 0, x > 224 or y > 128 - height.

See Sprite8 for more info about sprites.

ClipSprite32

void ClipSprite32 (short x, short y, short height, const unsigned long *sprite, void *vm_addr, short mode);

Safely draws a sprite with a width of 32 pixels or less on the screen.

ClipSprite32 works exactly like Sprite32, but it doesn't draw out of the boundaries of a 240x128 screen, unlike Sprite32 if given x < 0, y < 0, x > 208 or y > 128 - height.

See Sprite8 for more info about sprites.

Sprite8

void Sprite8 (short x, short y, short height, const unsigned char *sprite, void *vm_addr, short mode);

Draws a sprite with a width of 8 pixels or less on the screen.

Sprite8 draws a sprite with a width of 8 pixels or less on the screen. See ClipSprite8 for a version that handles out-of-screen sprites gracefully, and Sprite16, ClipSprite16, Sprite32 or ClipSprite32 for wider sprites. This routine is much faster than TIOS routines such as DrawIcon, BitmapPut, etc. x and y are the coordinates of the upper left corner of the sprite. height is the height of the sprite. sprite is a pointer to the array of unsigned characters which define the shape of the sprite (line by line). vm_addr is the pointer to the video plane; it should be LCD_MEM if you are not using grayscale or the PortSet function. mode is the drawing mode, and it may have one of the following values (these constants are defined in the enum SprtModes):

SPRT_XOR XOR the sprite into a background. This is used only for non-masked sprites. XOR mode switches every pixel with a corresponding '1' bit in the sprite array from white to black and verse vica.

SPRT_OR OR the sprite into a background. This is mainly used for masked sprites together with SPRT_AND. OR means that every pixel with a corresponding '1' bit in the sprite array will be set to black, but all other pixels stay the same. If you want to turn all other pixels to white instead, use SPRT_RPLC.

SPRT_AND AND the sprite into a background. This is used for masked sprites together with SPRT_OR. AND turns off every pixel with a corresponding '0' bit in the sprite array, but all other pixels remain untouched. If you want to turn all other pixels to black instead, use SPRT_RPLC.

SPRT_RPLC RePLaCe the sprite into a background. RPLC sets every pixel with a corresponding '1' bit to black and every pixel with a corresponding '0' bit to white. This is equivalent to calling Sprite8(x,y,h,sprite,plane,SPRT_AND); Sprite8(x,y,h,sprite,plane,SPRT_OR);.

In fact, you can use one of two techniques to draw sprites:

Non-masked sprites. Using this method, the sprites are simply XORed into the background. This technique was popular in many games on old 8-bit computers. To erase the sprite, it is enough to call the routine again on the same position.
Masked sprites. This is the more advanced method, which needs more programming practice, but produces much better results. Using this method, you first need to erase a part of the background which occupies a space where the sprite need to be displayed, then to draw the actual sprite shape. To do this, AND the inverse of the sprite mask to the background, then OR the sprite at the same location. However, it is not so easy to restore the background later. For solving this problem, a lot of advanced methods are developed (like "double-buffering", etc.). These methods are quite common in advanced ASM games, and they are explained in many ASM tutorials.

Here is a simple example (called "Masked Sprite"), which first draws a simple "background", then draws a "masked" sprite (which is a simple 8x8 square with solid edges and blank interior) at (30,30):

// Display a masked sprite over an arbitrary background

#define USE_TI89              // Compile for TI-89
#define USE_TI92PLUS          // Compile for TI-92 Plus
#define USE_V200              // Compile for V200

#define OPTIMIZE_ROM_CALLS    // Use ROM Call Optimization
#define MIN_AMS 100           // Compile for AMS 1.00 or higher
#define SAVE_SCREEN           // Save/Restore LCD Contents

#include <tigcclib.h>         // Include All Header Files

// Main Function
void _main(void)
{
  static const unsigned char sprite[] = {0xFF,0x81,0x81,0x81,0x81,0x81,0x81,0xFF};
  static const unsigned char imask[] = {(unsigned char)~0xFF,(unsigned char)~0xFF,
    (unsigned char)~0xFF,(unsigned char)~0xFF,(unsigned char)~0xFF,
    (unsigned char)~0xFF,(unsigned char)~0xFF,(unsigned char)~0xFF};
  int i;
  ClrScr ();
  for (i = 0; i <= LCD_WIDTH; i++)
    DrawLine (i, 0, i, LCD_HEIGHT, A_SHADE_NS);  // A simple background
  Sprite8 (30, 30, 8, imask, LCD_MEM, SPRT_AND);
  Sprite8 (30, 30, 8, sprite, LCD_MEM, SPRT_OR);
  ngetchx ();
}

Here the sprite mask is {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}, but it needs to be inverted before passing it to the Sprite8 function. For this purpose, the operator '~' may be very useful. Note that '~' is "bitwise NOT". Of course, ~0xFF is the same as 0x00, but this notation makes the program more clear (and it does not increase the code size, because the inverting will be performed at compilation time). And if you want to use Sprite16, ClipSprite16, Sprite32 or ClipSprite32, the notation ~0xFF will still be valid in a short int array, or in a long int array if you add the 'L' suffix (see the respective info about Sprite32 and ClipSprite32). Without this notation, you must use 0x00 in Sprite8, but 0xFF00 in Sprite16/ClipSprite16, and 0xFFFFFF00 in Sprite32/ClipSprite32. This is why a notation like ~0xFF is more universal.

You can use binary numbers to define your sprites. On the one hand, it makes the program incompatible with some other C dialects. On the other hand, it makes designing a sprite much easier and also allows for editing the sprite at a later time without having to reconvert it. The binary representation of the sprite presented above would look like this:

static const unsigned char sprite[]={
0b11111111,
0b10000001,
0b10000001,
0b10000001,
0b10000001,
0b10000001,
0b10000001,
0b11111111};

Sprite16

void Sprite16 (short x, short y, short height, const unsigned short *sprite, void *vm_addr, short mode);

Draws a sprite with a width of 16 pixels or less on the screen.

Sprite16 works exactly like Sprite8, but it takes sprites with a width of 16 pixels. sprite is now a pointer to the array of unsigned short integers which defines the sprite. So, to define a sprite (or sprite mask), use something like

static const unsigned short sprite[] = {...};

See Sprite8 for more info about sprites, and ClipSprite16 for a version that handles out-of-screen sprites gracefully.

Sprite32

void Sprite32 (short x, short y, short height, const unsigned long *sprite, void *vm_addr, short mode);

Draws a sprite with a width of 32 pixels or less on the screen.

Sprite32 works exactly like Sprite8, but it takes sprites with a width of 32 pixels. sprite is now a pointer to the array of unsigned long integers which defines the sprite. So, to define a sprite (or sprite mask), use something like

static const unsigned long sprite[] = {...};

Note: If you define a sprite mask and invert it with the '~' operator, you need to take care of the possibility of the first two bytes being zero in one constant. In this case, the constant will be assumed to be a 16 bit value, so only 16 bits will be inverted. Then the constant is promoted to an unsigned long integer, and the first 16 bits are still zero as if they actually belonged to the mask. To take care of this problem, add the 'L' (long) suffix to the end of the value.

If you want to use sprites wider than 32 pixels (which is not very likely), one solution is to use a "kernel"-based program and graphlib::put_sprite (see Frequently Asked Questions for more info about how to do it). If you don't want to use kernel-based programs, the proposed method depends on what the use of the sprite will be:

If you don't need too fast action, the built-in TIOS function BitmapPut may be good enough.
If you need a very fast sprite routine for very large sprites, then you must write it yourself, or use prewritten ones in ExtGraph or Genlib.

See Sprite8 for more info about sprites, and ClipSprite32 for a version that handles out-of-screen sprites gracefully.

SprtModes

enum SprtModes {SPRT_XOR, SPRT_OR, SPRT_AND, SPRT_RPLC};

An enumeration to describe possible modes of sprite drawing.

This type is used by all sprite functions.

SPRT_XOR	XOR the sprite into a background. This is used only for non-masked sprites. XOR mode switches every pixel with a corresponding '1' bit in the sprite array from white to black and verse vica.
SPRT_OR	OR the sprite into a background. This is mainly used for masked sprites together with SPRT_AND. OR means that every pixel with a corresponding '1' bit in the sprite array will be set to black, but all other pixels stay the same. If you want to turn all other pixels to white instead, use SPRT_RPLC.
SPRT_AND	AND the sprite into a background. This is used for masked sprites together with SPRT_OR. AND turns off every pixel with a corresponding '0' bit in the sprite array, but all other pixels remain untouched. If you want to turn all other pixels to black instead, use SPRT_RPLC.
SPRT_RPLC	RePLaCe the sprite into a background. RPLC sets every pixel with a corresponding '1' bit to black and every pixel with a corresponding '0' bit to white. This is equivalent to calling `Sprite8(x,y,h,sprite,plane,SPRT_AND); Sprite8(x,y,h,sprite,plane,SPRT_OR);`.