qmk_firmware/quantum/led_matrix/animations/wave_left_right_anim.h

#ifdef ENABLE_LED_MATRIX_WAVE_LEFT_RIGHT
LED_MATRIX_EFFECT(WAVE_LEFT_RIGHT)
#    ifdef LED_MATRIX_CUSTOM_EFFECT_IMPLS

static uint8_t WAVE_LEFT_RIGHT_math(uint8_t val, uint8_t i, uint8_t time) {
    return scale8(sin8(g_led_config.point[i].x - time), val);
}

bool WAVE_LEFT_RIGHT(effect_params_t* params) {
    return effect_runner_i(params, &WAVE_LEFT_RIGHT_math);
}

#    endif // LED_MATRIX_CUSTOM_EFFECT_IMPLS
#endif     // ENABLE_LED_MATRIX_WAVE_LEFT_RIGHT