// Includes
#include <PA9.h> // Include for PA_Lib
// Graphics Includes
// --- Sprites ---
// gfx2gba -D -fsrc -pSprites.pal -t8 SpaceShip.bmp
#include "gfx/Pig.raw.c"
#include "gfx/Sprites.pal.c"
// Global Variables
u8 Sprite1_X = 31; // X position of Sprite 1
u8 Sprite1_Y = 63; // Y position of Sprite 1
u8 Sprite2_X = 159; // X position of Sprite 2
u8 Sprite2_Y = 63; // Y position of Sprite 2
u8 Sprite3_X = 31; // X position of Sprite 3
u8 Sprite3_Y = 63; // Y position of Sprite 3
u8 Sprite4_X = 159; // X position of Sprite 4
u8 Sprite4_Y = 63; // Y position of Sprite 4
u16 Rotate = 0; // Rotation angle (0-512)
u16 Zoom_X = 128; // Amount to zoom horizontally
u16 Zoom_Y = 128; // Amount to zoom vertically
bool increment = true; // Used to zoom in or out
// Function: main()
int main(int argc, char ** argv)
{
PA_Init(); // Initializes PA_Lib
PA_InitVBL(); // Initializes a standard VBL
//PA_LoadSplash(); // PA_Lib splash screen
// Setup text system and write labels to the screens
PA_InitText(0, 0);
PA_InitText(1, 0);
PA_SetTextCol(0, 31, 31, 31);
PA_SetTextCol(1, 31, 31, 31);
PA_OutputSimpleText(1, 3, 7, "Sprite #1");
PA_OutputSimpleText(1, 5, 15, "Plain");
PA_OutputSimpleText(1, 19, 7, "Sprite #2");
PA_OutputSimpleText(1, 21, 15,"Rotate");
PA_OutputSimpleText(0, 3, 7, "Sprite #3");
PA_OutputSimpleText(0, 6, 15, "Zoom");
PA_OutputSimpleText(0, 19, 7, "Sprite #4");
PA_OutputSimpleText(0, 17, 15,"Rotate + Zoom");
// Load palettes
PA_LoadPal(PAL_SPRITE0, Sprites_Palette);
PA_LoadPal(PAL_SPRITE1, Sprites_Palette);
// Load sprites
PA_CreateSprite(1,0,(void*)Pig_Bitmap,OBJ_SIZE_64X64,
1,0,Sprite1_X,Sprite1_Y); // Sprite 1
PA_CreateSpriteEx(1,1,(void*)Pig_Bitmap,OBJ_SIZE_64X64,
1,0,0,0,0,0,0,0,Sprite2_X,Sprite2_Y); // Sprite 2
PA_CreateSpriteEx(0,0,(void*)Pig_Bitmap,OBJ_SIZE_64X64,
1,0,0,0,0,0,0,0,Sprite3_X,Sprite3_Y); // Sprite 3
PA_CreateSpriteEx(0,1,(void*)Pig_Bitmap,OBJ_SIZE_64X64,
1,0,0,0,0,0,0,0,Sprite4_X,Sprite4_Y); // Sprite 4
// Enable rotate & zoom
PA_SetSpriteRotEnable(1,1,0); // Sprite 2
PA_SetSpriteRotEnable(0,0,0); // Sprite 3
PA_SetSpriteRotEnable(0,1,1); // Sprite 4
// *** Set initial rotate & zoom amounts ***
PA_SetRotset(1,0,Rotate,256,256); // Sprite 2
PA_SetRotset(0,0,0,Zoom_X,Zoom_Y); // Sprite 3
PA_SetRotset(0,1,Rotate,Zoom_X,Zoom_Y); // Sprite 4
// Infinite loop to keep the program running
while (1)
{
// Increment Rotate angle
(Rotate<512) ? ++Rotate : Rotate=0;
// De/Increase Zoom amount
if (increment) {
Zoom_Y = (Zoom_X += 4);
if (Zoom_X == 512) increment=false;
} else {
Zoom_Y = (Zoom_X -= 4);
if (Zoom_X == 128) increment=true;
}
// Rotate and/or zoom sprites
PA_SetRotset(1,0,Rotate,256,256); // Sprite 2
PA_SetRotset(0,0,0,Zoom_X,Zoom_Y); // Sprite 3
PA_SetRotset(0,1,Rotate,Zoom_X,Zoom_Y); // Sprite 4
PA_WaitForVBL();
}
return 0;
} // End of main()
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Code
Explanation
u16 Rotate = 0;
This will be used in the PA_SetRotset() function later. The main
thing to remember is that the rotation angle goes from 0 - 512 (not
360!).
u16 Zoom_X = 128; u16 Zoom_Y = 128;
This will also be used in the PA_SetRotset() function later. The
key here is that 128 = 2x zoom, 256 = no zoom, and 512 = 1/2 zoom.
PA_SetSpriteRotEnable();
This is used to setup the rotation for a sprite. Its parameters are
screen - 0 or 1
sprite - slot of sprite you want to rotate
rotset-
rotation set to assign a sprite. There can be from 0-31
rotsets per screen. You can assign multiple sprites to the same
rotset if you plan on rotating/zooming them identically. You
should notice that sprite 2 is on screen 1, in slot 1, and assigned
rotset 0. Sprite 3 is on screen 0, in slot 0, and assigned rotset
0. Sprite 4 is on screen 0, in slot 1, and assigned rotset 1.
Sprite 1, of course, doesn't get rotated or zoomed, so that's why
it's not included here.
(Rotate<512) ? ++Rotate : Rotate=0;
I used this type of command in a previous tutorial, so I hope you know
it by now. Basically I am incrementing the rotation angle
variable from 0-512 (and around and around again).
if (increment) {...}
This section of code just increments the zoom variables from 0-512 (by
4 each time) and then back down to 0 (where it starts over again).
This gives you the effect of zooming in and then back out of a
sprite.
PA_SetRotset(1,0,Rotate,256,256); // Sprite 2
PA_SetRotset(0,0,0,Zoom_X,Zoom_Y); // Sprite 3
PA_SetRotset(0,1,Rotate,Zoom_X,Zoom_Y); // Sprite 4
This is where all of the work of the program is taking place.
Hopefully you are able to run the demo on hardware so you can see
what is going on - that will make this much easier to understand!
The parameters are as follows:
screen - 0 or 1
rotset - rotset you want to change. See PA_SetSpriteRotEnable() above.
angle - rotation angle, can be from 0 - 512 (not 0 - 360!)
zoomx - horizontal zoom, 128 is 2x, 256 is no zoom, and 512 is 1/2 zoom
zoomy - vertical zoom, 128 is 2x, 256 is no zoom, and 512 is 1/2 zoom
That's it! It's just that easy... well, pretty much. One
note, the first set of calls to PA_SetRotset() were included because
the default setting for rotate/zoom were not set in PA_Lib and
therefore you would get a weird graphical glitch if you called this
function more than one VBL later than PA_SetSpriteRotEnable().
This behavior will be changed in the next version of PA_Lib.
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