main.c File Reference

16.16 fixed-point orbit demo (B5 capstone) More...

#include <snes.h>
#include <snes/fixed32.h>

Functions
int	main (void)

Variables
fixed32	g_angle
u8	g_angle8
fixed32	g_omega
fixed32	g_radius
s16	g_sx
s16	g_sy
static const u8	orbiter_pal [4]
static const u8	orbiter_tile [32]

Detailed Description

16.16 fixed-point orbit demo (B5 capstone)

A single 8x8 sprite orbits the screen centre. The orbit is driven entirely by the lib's <snes/fixed32.h> API — fix32Sin, fix32Cos, fix32Mul, plus straight Kl arithmetic on fixed32 accumulators.

What this example demonstrates

• fixed32 (s32 16.16) for an angle accumulator that stays smooth across many frames without 8.8 rounding drift.
• fix32Sin / fix32Cos lifted from the 8.8 LUT to 16.16 (8 bits of fractional precision, ~25 cycles each — adequate for sub-pixel animation).
• fix32Mul(radius, fix32Cos(angle)) as the canonical pattern for trig-driven motion: a radius * sin/cos term used in every 2D game that needs aim/orbit/parallax-around-a-point.

Inputs / interaction

None — the sprite orbits autonomously. The example is structured as the simplest possible fixed32 fixture; later examples (likemario, aim_target, breakout) compose the same primitives into game logic.

Modules Used

console, sprite, dma, background, fixed32, math

Function Documentation

main()

int main

(

void

)

Variable Documentation

g_angle

fixed32 g_angle

g_angle8

u8 g_angle8

g_omega

fixed32 g_omega

g_radius

fixed32 g_radius

g_sx

s16 g_sx

g_sy

s16 g_sy

orbiter_pal

const u8 orbiter_pal[4]

static

Initial value:

                            = {
    0x00, 0x00,
    0xFF, 0x7F,
}

orbiter_tile

const u8 orbiter_tile[32]

static

Initial value:

                             = {
    
    0xFF, 0, 0xFF, 0, 0xFF, 0, 0xFF, 0,   
    0xFF, 0, 0xFF, 0, 0xFF, 0, 0xFF, 0,   
    0, 0, 0, 0, 0, 0, 0, 0,               
    0, 0, 0, 0, 0, 0, 0, 0,               
}