Starfield

Source: src/starfield.c · 61 lines · 4 functions.

Module entry points

These functions are exposed to the rest of the project. Open one to follow its decisions and the helpers it calls.

starfield_initialize()starfield_update()starfield_draw()

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Functions in this file

paletteCount starfield_initialize starfield_update starfield_draw

paletteCount() · source line 14

static unsigned paletteCount(starfield_palette_t palette)

Exit this functionreturn palette == STARFIELD_COLOUR ? sizeof(colour_colours) / sizeof(colour_colours[0]) : sizeof(greyscale_colours) / sizeof(greyscale_colours[0]);

Read original function source

static unsigned paletteCount(starfield_palette_t palette)
{
    return palette == STARFIELD_COLOUR ? sizeof(colour_colours) / sizeof(colour_colours[0]) :
        sizeof(greyscale_colours) / sizeof(greyscale_colours[0]);
}

starfield_initialize() · source line 20

void starfield_initialize(starfield_t *field, unsigned count, int left, int top,
                          int width, int height, starfield_palette_t palette)

Calls into this documentation:

paletteCount()

Decisionfield == NULL || width <= 0 || height <= 0
True
1. Exit this functionreturn;
False
Continue after this decision.
Executefield->count = count > STARFIELD_MAX_STARS ? STARFIELD_MAX_STARS : (uint8_t)count;
Executefield->palette = palette;
Executeconst unsigned shades = paletteCount(palette);
FOR loopunsigned i = 0; i < field->count; ++i
Repeat body while the loop condition permits; then continue below.
1. 1. Executefield->stars[i] = (starfield_star_t){ .x = (uint16_t)(left + esp_random() % (unsigned)width), .y = (uint16_t)(top + esp_random() % (unsigned)height), .twinkle_delay = 150U + esp_random() % 651U, .shade = (uint8_t)(esp_random() % shades), };

Read original function source

void starfield_initialize(starfield_t *field, unsigned count, int left, int top,
                          int width, int height, starfield_palette_t palette)
{
    if (field == NULL || width <= 0 || height <= 0) return;
    field->count = count > STARFIELD_MAX_STARS ? STARFIELD_MAX_STARS : (uint8_t)count;
    field->palette = palette;
    const unsigned shades = paletteCount(palette);
    for (unsigned i = 0; i < field->count; ++i) {
        field->stars[i] = (starfield_star_t){
            .x = (uint16_t)(left + esp_random() % (unsigned)width),
            .y = (uint16_t)(top + esp_random() % (unsigned)height),
            .twinkle_delay = 150U + esp_random() % 651U,
            .shade = (uint8_t)(esp_random() % shades),
        };
    }
}

starfield_update() · source line 37

void starfield_update(starfield_t *field, uint32_t elapsed_ms)

Calls into this documentation:

paletteCount()

Decisionfield == NULL
True
1. Exit this functionreturn;
False
Continue after this decision.
Executeconst unsigned shades = paletteCount(field->palette);
FOR loopunsigned i = 0; i < field->count; ++i
Repeat body while the loop condition permits; then continue below.
1. 1. Executestarfield_star_t *star = &field->stars[i];
  2. Decisionelapsed_ms < star->twinkle_delay
    True
    Executestar->twinkle_delay -= elapsed_ms;
    False
    Executestar->shade = (uint8_t)((star->shade + 1U + esp_random() % (shades - 1U)) % shades);
    Executestar->twinkle_delay = 150U + esp_random() % 651U;

Read original function source

void starfield_update(starfield_t *field, uint32_t elapsed_ms)
{
    if (field == NULL) return;
    const unsigned shades = paletteCount(field->palette);
    for (unsigned i = 0; i < field->count; ++i) {
        starfield_star_t *star = &field->stars[i];
        if (elapsed_ms < star->twinkle_delay) {
            star->twinkle_delay -= elapsed_ms;
        } else {
            star->shade = (uint8_t)((star->shade + 1U + esp_random() % (shades - 1U)) % shades);
            star->twinkle_delay = 150U + esp_random() % 651U;
        }
    }
}

starfield_draw() · source line 52

void starfield_draw(uint16_t *frame, const starfield_t *field)

Calls into this documentation:

paletteCount()fill_rect()

Decisionframe == NULL || field == NULL
True
1. Exit this functionreturn;
False
Continue after this decision.
Executeconst uint16_t *colours = field->palette == STARFIELD_COLOUR ? colour_colours : greyscale_colours;
Executeconst unsigned shades = paletteCount(field->palette);
FOR loopunsigned i = 0; i < field->count; ++i
Repeat body while the loop condition permits; then continue below.
1. 1. Executeconst starfield_star_t *star = &field->stars[i];
  2. Executefill_rect(frame, star->x, star->y, 1, 1, colours[star->shade % shades]);

Read original function source

void starfield_draw(uint16_t *frame, const starfield_t *field)
{
    if (frame == NULL || field == NULL) return;
    const uint16_t *colours = field->palette == STARFIELD_COLOUR ? colour_colours : greyscale_colours;
    const unsigned shades = paletteCount(field->palette);
    for (unsigned i = 0; i < field->count; ++i) {
        const starfield_star_t *star = &field->stars[i];
        fill_rect(frame, star->x, star->y, 1, 1, colours[star->shade % shades]);
    }
}

Complete original file, including constants and data

/* Coded By JD(2026) */
#error "Reference listing only — not provided as build-ready source."
#include "starfield.h"
#include "esp_random.h"
#include "game_graphics.h"
#include <stddef.h>

static const uint16_t greyscale_colours[] = {
    RGB565(48, 48, 48), RGB565(88, 88, 88), RGB565(136, 136, 136),
    RGB565(192, 192, 192), RGB565(248, 248, 248),
};
static const uint16_t colour_colours[] = {
    COLOR_DARKCYAN, COLOR_CYAN, COLOR_YELLOW, COLOR_MAGENTA, COLOR_LIGHTGRAY, COLOR_RED,
};

static unsigned paletteCount(starfield_palette_t palette)
{
    return palette == STARFIELD_COLOUR ? sizeof(colour_colours) / sizeof(colour_colours[0]) :
        sizeof(greyscale_colours) / sizeof(greyscale_colours[0]);
}

void starfield_initialize(starfield_t *field, unsigned count, int left, int top,
                          int width, int height, starfield_palette_t palette)
{
    if (field == NULL || width <= 0 || height <= 0) return;
    field->count = count > STARFIELD_MAX_STARS ? STARFIELD_MAX_STARS : (uint8_t)count;
    field->palette = palette;
    const unsigned shades = paletteCount(palette);
    for (unsigned i = 0; i < field->count; ++i) {
        field->stars[i] = (starfield_star_t){
            .x = (uint16_t)(left + esp_random() % (unsigned)width),
            .y = (uint16_t)(top + esp_random() % (unsigned)height),
            .twinkle_delay = 150U + esp_random() % 651U,
            .shade = (uint8_t)(esp_random() % shades),
        };
    }
}

void starfield_update(starfield_t *field, uint32_t elapsed_ms)
{
    if (field == NULL) return;
    const unsigned shades = paletteCount(field->palette);
    for (unsigned i = 0; i < field->count; ++i) {
        starfield_star_t *star = &field->stars[i];
        if (elapsed_ms < star->twinkle_delay) {
            star->twinkle_delay -= elapsed_ms;
        } else {
            star->shade = (uint8_t)((star->shade + 1U + esp_random() % (shades - 1U)) % shades);
            star->twinkle_delay = 150U + esp_random() % 651U;
        }
    }
}

void starfield_draw(uint16_t *frame, const starfield_t *field)
{
    if (frame == NULL || field == NULL) return;
    const uint16_t *colours = field->palette == STARFIELD_COLOUR ? colour_colours : greyscale_colours;
    const unsigned shades = paletteCount(field->palette);
    for (unsigned i = 0; i < field->count; ++i) {
        const starfield_star_t *star = &field->stars[i];
        fill_rect(frame, star->x, star->y, 1, 1, colours[star->shade % shades]);
    }
}