// license:BSD-3-Clause // copyright-holders:Fabio Priuli /********************************************************************** Sega Master System "Light Phaser" (light gun) emulation Release data from the Sega Retro project: Year: 1986 Country/region: US Model code: 3050 Year: 1987 Country/region: EU Model code: ? Year: 1989 Country/region: BR Model code: 010470 Year: 198? Country/region: KR Model code: ? Notes: The Light Phaser gun doesn't work with the Sega Mark III. **********************************************************************/ #include "emu.h" #include "screen.h" #include "lphaser.h" //************************************************************************** // DEVICE DEFINITIONS //************************************************************************** DEFINE_DEVICE_TYPE(SMS_LIGHT_PHASER, sms_light_phaser_device, "sms_light_phaser", "Sega SMS Light Phaser") #define LGUN_RADIUS 6 #define LGUN_X_INTERVAL 4 READ_LINE_MEMBER( sms_light_phaser_device::th_pin_r ) { // The returned value is inverted due to IP_ACTIVE_LOW mapping. return ~m_sensor_last_state; } INPUT_CHANGED_MEMBER( sms_light_phaser_device::position_changed ) { if (newval != oldval) { sensor_check(0); } } static INPUT_PORTS_START( sms_light_phaser ) PORT_START("CTRL_PORT") PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_BUTTON1 ) // TL (trigger) PORT_BIT( 0x40, IP_ACTIVE_LOW, IPT_CUSTOM ) PORT_READ_LINE_DEVICE_MEMBER(DEVICE_SELF, sms_light_phaser_device, th_pin_r) PORT_BIT( 0x9f, IP_ACTIVE_LOW, IPT_UNUSED ) PORT_START("LPHASER_X") PORT_BIT( 0xff, 0x00, IPT_LIGHTGUN_X) PORT_CROSSHAIR(X, 1.0, 0.0, 0) PORT_SENSITIVITY(50) PORT_KEYDELTA(15) PORT_CHANGED_MEMBER(DEVICE_SELF, sms_light_phaser_device, position_changed, 0) PORT_START("LPHASER_Y") PORT_BIT( 0xff, 0x00, IPT_LIGHTGUN_Y) PORT_CROSSHAIR(Y, 1.0, 0.0, 0) PORT_SENSITIVITY(50) PORT_KEYDELTA(15) PORT_CHANGED_MEMBER(DEVICE_SELF, sms_light_phaser_device, position_changed, 0) INPUT_PORTS_END //------------------------------------------------- // input_ports - device-specific input ports //------------------------------------------------- ioport_constructor sms_light_phaser_device::device_input_ports() const { return INPUT_PORTS_NAME( sms_light_phaser ); } //************************************************************************** // LIVE DEVICE //************************************************************************** //------------------------------------------------- // sms_light_phaser_device - constructor //------------------------------------------------- sms_light_phaser_device::sms_light_phaser_device(const machine_config &mconfig, const char *tag, device_t *owner, const XTAL &clock) : device_t(mconfig, SMS_LIGHT_PHASER, tag, owner, clock), device_sms_control_port_interface(mconfig, *this), m_lphaser_pins(*this, "CTRL_PORT"), m_lphaser_x(*this, "LPHASER_X"), m_lphaser_y(*this, "LPHASER_Y"), m_sensor_last_state(0), m_lphaser_timer(nullptr) { } //------------------------------------------------- // device_start - device-specific startup //------------------------------------------------- void sms_light_phaser_device::device_start() { save_item(NAME(m_sensor_last_state)); m_lphaser_timer = timer_alloc(FUNC(sms_light_phaser_device::sensor_check), this); } void sms_light_phaser_device::device_reset() { m_sensor_last_state = 1; // off (1) } //------------------------------------------------- // sms_peripheral_r - light phaser read //------------------------------------------------- uint8_t sms_light_phaser_device::peripheral_r() { return m_lphaser_pins->read(); } /* Light Phaser (light gun) emulation notes: - The sensor is activated based on the brightness of individual pixels being drawn by the beam, in circular area where the gun is aiming. - Currently, brightness is calculated based only on single pixels. - In general, after the trigger is pressed, games draw the next frame using a bright pattern, to make sure the sensor will be activated. If the emulation skips that frame, the sensor may stay deactivated. Setting frameskip to 0 is recommended to avoid problems. - When the sensor switches from on (0) to off (1), a value is latched for the HCount register. - When the sensor switches from off to on, a flag is set. The emulation uses this flag to signal that the TH line is activated during status reads of the input port. After reading, the flag is cleared, or it is cleared when the Pause status is read at the end of a frame. This is necessary because the "Color & Switch Test" ROM only reads the TH state after VINT occurs. - The gun test in "Color & Switch Test" is an example that requires checks of the sensor status independent of other events, like trigger press or TH bit reads. Another example is the title screen of "Hang-On & Safari Hunt", where the game only reads the HCount register in a loop, expecting a latch by the gun. - The whole procedure is managed by a periodic timer callback, which is scheduled to run in intervals when the beam is within the circular area. */ int sms_light_phaser_device::bright_aim_area(int lgun_x, int lgun_y) { const int r_x_r = LGUN_RADIUS * LGUN_RADIUS; const rectangle &visarea = m_port->m_screen->visible_area(); rectangle aim_area; int beam_x = m_port->m_screen->hpos(); int beam_y = m_port->m_screen->vpos(); int beam_x_orig = beam_x; int beam_y_orig = beam_y; int result = 1; bool new_check_point = false; aim_area.min_y = std::max(lgun_y - LGUN_RADIUS, visarea.min_y); aim_area.max_y = std::min(lgun_y + LGUN_RADIUS, visarea.max_y); while (!new_check_point) { /* If beam's y doesn't point to a line where the aim area is, change it to the first line where the beam enters that area. */ if (beam_y < aim_area.min_y || beam_y > aim_area.max_y) { beam_y = aim_area.min_y; } int dy = abs(beam_y - lgun_y); /* Caculate distance in x of the radius, relative to beam's y distance. First try some shortcuts. */ double dx_radius = 0; if (dy == 0) { dx_radius = LGUN_RADIUS; } else if (dy != LGUN_RADIUS) { /* step 1: r^2 = dx^2 + dy^2 */ /* step 2: dx^2 = r^2 - dy^2 */ /* step 3: dx = sqrt(r^2 - dy^2) */ dx_radius = ceil(sqrt(double(r_x_r - (dy * dy)))); } aim_area.min_x = std::max(int32_t(lgun_x - dx_radius), visarea.min_x); aim_area.max_x = std::min(int32_t(lgun_x + dx_radius), visarea.max_x); while (!new_check_point) { /* If beam's x has passed the aim area, change it to the next line and go back to recheck y/x coordinates. */ if (beam_x > aim_area.max_x) { beam_x = visarea.min_x; beam_y++; break; } /* If beam's x isn't in the aim area, change it to the next point where the beam enters that area. */ if (beam_x < aim_area.min_x) { beam_x = aim_area.min_x; } if (beam_x_orig != beam_x || beam_y_orig != beam_y) { /* adopt the new coordinates to adjust the timer */ new_check_point = true; break; } if (m_sensor_last_state == 0) { /* sensor is already on */ /* keep sensor on until out of the aim area */ result = 0; } else { rgb_t color; uint8_t brightness; /* brightness of the lightgray color in the frame drawn by Light Phaser games */ const uint8_t sensor_min_brightness = 0x7f; m_port->m_screen->update_now(); color = m_port->m_screen->pixel(beam_x, beam_y); /* reference: http://www.w3.org/TR/AERT#color-contrast */ brightness = (color.r() * 0.299) + (color.g() * 0.587) + (color.b() * 0.114); //printf ("color brightness: %2X for x %d y %d\n", brightness, beam_x, beam_y); result = (brightness >= sensor_min_brightness) ? 0 : 1; } if (result == 0) /* sensor on */ { /* Set next check for when sensor will be off */ beam_x = aim_area.max_x + 1; /* adopt the new coordinates to adjust the timer */ new_check_point = true; } else { /* Next check will happen after the minimum interval */ beam_x += LGUN_X_INTERVAL; } } } m_lphaser_timer->adjust(m_port->m_screen->time_until_pos(beam_y, beam_x)); return result; } uint16_t sms_light_phaser_device::screen_hpos_nonscaled(int scaled_hpos) { const rectangle &visarea = m_port->m_screen->visible_area(); int offset_x = (scaled_hpos * (visarea.max_x - visarea.min_x)) / 255; return visarea.min_x + offset_x; } uint16_t sms_light_phaser_device::screen_vpos_nonscaled(int scaled_vpos) { const rectangle &visarea = m_port->m_screen->visible_area(); int offset_y = (scaled_vpos * (visarea.max_y - visarea.min_y)) / 255; return visarea.min_y + offset_y; } TIMER_CALLBACK_MEMBER(sms_light_phaser_device::sensor_check) { const int x = screen_hpos_nonscaled(m_lphaser_x->read()); const int y = screen_vpos_nonscaled(m_lphaser_y->read()); int sensor_new_state = bright_aim_area(x, y); if (sensor_new_state != m_sensor_last_state) { m_port->th_pin_w(sensor_new_state); m_sensor_last_state = sensor_new_state; } }