qmk-firmware/quantum/rgb_matrix_animations/solid_reactive_nexus.h

#ifdef RGB_MATRIX_KEYREACTIVE_ENABLED
#if !defined(DISABLE_RGB_MATRIX_SOLID_REACTIVE_NEXUS) || !defined(DISABLE_RGB_MATRIX_SOLID_REACTIVE_MULTINEXUS)

#ifndef DISABLE_RGB_MATRIX_SOLID_REACTIVE_NEXUS
RGB_MATRIX_EFFECT(SOLID_REACTIVE_NEXUS)
#endif

#ifndef DISABLE_RGB_MATRIX_SOLID_REACTIVE_MULTINEXUS
RGB_MATRIX_EFFECT(SOLID_REACTIVE_MULTINEXUS)
#endif

#ifdef RGB_MATRIX_CUSTOM_EFFECT_IMPLS

static HSV SOLID_REACTIVE_NEXUS_math(HSV hsv,  int16_t dx, int16_t dy, uint8_t dist, uint16_t tick) {
    uint16_t effect = tick - dist;
    if (effect > 255)
        effect = 255;
    if (dist > 72)
        effect = 255;
    if ((dx > 8 || dx < -8) && (dy > 8 || dy < -8))
        effect = 255;
    hsv.v = qadd8(hsv.v, 255 - effect);
    hsv.h = rgb_matrix_config.hsv.h + dy / 4;
    return hsv;
}

#ifndef DISABLE_RGB_MATRIX_SOLID_REACTIVE_NEXUS
bool SOLID_REACTIVE_NEXUS(effect_params_t* params) {
    return effect_runner_reactive_splash(qsub8(g_last_hit_tracker.count, 1), params, &SOLID_REACTIVE_NEXUS_math);
}
#endif

#ifndef DISABLE_RGB_MATRIX_SOLID_REACTIVE_MULTINEXUS
bool SOLID_REACTIVE_MULTINEXUS(effect_params_t* params) {
    return effect_runner_reactive_splash(0, params, &SOLID_REACTIVE_NEXUS_math);
}
#endif

#endif // RGB_MATRIX_CUSTOM_EFFECT_IMPLS
#endif // !defined(DISABLE_RGB_MATRIX_SOLID_REACTIVE_NEXUS) || !defined(DISABLE_RGB_MATRIX_SOLID_REACTIVE_MULTINEXUS)
#endif // RGB_MATRIX_KEYREACTIVE_ENABLED