int Game_Main(void *parms, int num_parms)
{
// this is the workhorse of your game it will be called
// continuously in real-time this is like main() in C
// all the calls for you game go here!
int index, index_x, index_y; // looping vars
// check of user is trying to exit
if (KEY_DOWN(VK_ESCAPE) || KEY_DOWN(VK_SPACE))
PostMessage(main_window_handle, WM_DESTROY,0,0);
// start the timing clock
Start_Clock();
// clear the drawing surface
DDraw_Fill_Surface(lpddsback, 0);
// move the aliens
for (index = 0; index<NUM_ALIENS; index++)
Move_BOB(&aliens[index]);
// draw the aliens
for (index = 0; index<NUM_ALIENS; index++)
Draw_BOB(&aliens[index], lpddsback);
#ifndef USE_MULTITHREADING
// animate the aliens -- color animation
Rotate_Colors(249, 253);
#endif
// draw some info
Draw_Text_GDI("<ESC> to Exit.",8,8,RGB(0,255,0),lpddsback);
// flip the surfaces
DDraw_Flip();
// sync to 30 fps
Wait_Clock(30);
// return success
return(1);
} // end Game_Main
int Game_Main(void *parms)
{
// this is the workhorse of your game it will be called
// continuously in real-time this is like main() in C
// all the calls for you game go here!
int index; // looping var
int dx,dy; // general deltas used in collision detection
static int player_moving = 0; // tracks player motion
static PALETTEENTRY glow = {0,0,0,PC_NOCOLLAPSE}; // used to animation red border
static int glow_count = 0, glow_dx = 5;
// start the timing clock
Start_Clock();
// clear the drawing surface
DDraw_Fill_Surface(lpddsback, 0);
// lock the back buffer
DDraw_Lock_Back_Surface();
// draw the background reactor image
Draw_Bitmap(&reactor, back_buffer, back_lpitch, 0);
// unlock the back buffer
DDraw_Unlock_Back_Surface();
// read keyboard and other devices here
DInput_Read_Keyboard();
// reset motion flag
player_moving = 0;
// test direction of motion, this is a good example of testing the keyboard
// although the code could be optimized this is more educational
if (keyboard_state[DIK_RIGHT] && keyboard_state[DIK_UP])
{
// move skelaton
skelaton.x+=2;
skelaton.y-=2;
dx=2; dy=-2;
// set motion flag
player_moving = 1;
// check animation needs to change
if (skelaton.curr_animation != SKELATON_NEAST)
Set_Animation_BOB(&skelaton,SKELATON_NEAST);
} // end if
else
if (keyboard_state[DIK_LEFT] && keyboard_state[DIK_UP])
{
// move skelaton
skelaton.x-=2;
skelaton.y-=2;
dx=-2; dy=-2;
// set motion flag
player_moving = 1;
// check animation needs to change
if (skelaton.curr_animation != SKELATON_NWEST)
Set_Animation_BOB(&skelaton,SKELATON_NWEST);
} // end if
else
if (keyboard_state[DIK_LEFT] && keyboard_state[DIK_DOWN])
{
// move skelaton
skelaton.x-=2;
skelaton.y+=2;
dx=-2; dy=2;
// set motion flag
player_moving = 1;
// check animation needs to change
if (skelaton.curr_animation != SKELATON_SWEST)
Set_Animation_BOB(&skelaton,SKELATON_SWEST);
} // end if
else
if (keyboard_state[DIK_RIGHT] && keyboard_state[DIK_DOWN])
{
// move skelaton
skelaton.x+=2;
skelaton.y+=2;
dx=2; dy=2;
// set motion flag
player_moving = 1;
// check animation needs to change
if (skelaton.curr_animation != SKELATON_SEAST)
Set_Animation_BOB(&skelaton,SKELATON_SEAST);
} // end if
else
if (keyboard_state[DIK_RIGHT])
{
// move skelaton
skelaton.x+=2;
dx=2; dy=0;
// set motion flag
player_moving = 1;
// check animation needs to change
if (skelaton.curr_animation != SKELATON_EAST)
Set_Animation_BOB(&skelaton,SKELATON_EAST);
} // end if
else
if (keyboard_state[DIK_LEFT])
{
// move skelaton
skelaton.x-=2;
dx=-2; dy=0;
// set motion flag
player_moving = 1;
// check animation needs to change
if (skelaton.curr_animation != SKELATON_WEST)
Set_Animation_BOB(&skelaton,SKELATON_WEST);
} // end if
else
if (keyboard_state[DIK_UP])
{
// move skelaton
skelaton.y-=2;
dx=0; dy=-2;
// set motion flag
player_moving = 1;
// check animation needs to change
if (skelaton.curr_animation != SKELATON_NORTH)
Set_Animation_BOB(&skelaton,SKELATON_NORTH);
} // end if
else
if (keyboard_state[DIK_DOWN])
{
// move skelaton
skelaton.y+=2;
dx=0; dy=+2;
// set motion flag
player_moving = 1;
// check animation needs to change
if (skelaton.curr_animation != SKELATON_SOUTH)
Set_Animation_BOB(&skelaton,SKELATON_SOUTH);
} // end if
// only animate if player is moving
if (player_moving)
{
// animate skelaton
Animate_BOB(&skelaton);
// see if skelaton hit a wall
// lock surface, so we can scan it
DDraw_Lock_Back_Surface();
// call the color scanner with WALL_ANIMATION_COLOR, the color of the glowing wall
// try to center the scan in the center of the object to make it
// more realistic
if (Color_Scan(skelaton.x+16, skelaton.y+16,
skelaton.x+skelaton.width-16, skelaton.y+skelaton.height-16,
WALL_ANIMATION_COLOR, WALL_ANIMATION_COLOR, back_buffer,back_lpitch))
{
// back the skelaton up along its last trajectory
skelaton.x-=dx;
skelaton.y-=dy;
} // end if
// done, so unlock
DDraw_Unlock_Back_Surface();
// check if skelaton is off screen
if (skelaton.x < 0 || skelaton.x > (screen_width - skelaton.width))
skelaton.x-=dx;
if (skelaton.y < 0 || skelaton.y > (screen_height - skelaton.height))
skelaton.y-=dy;
} // end if
// draw the skelaton
Draw_BOB(&skelaton, lpddsback);
// animate color
glow.peGreen+=glow_dx;
// test boundary
if (glow.peGreen == 0 || glow.peGreen == 255)
glow_dx = -glow_dx;
Set_Palette_Entry(WALL_ANIMATION_COLOR, &glow);
// draw some text
Draw_Text_GDI("I STILL HAVE A BONE TO PICK!",0,screen_height - 32,WALL_ANIMATION_COLOR,lpddsback);
Draw_Text_GDI("USE ARROW KEYS TO MOVE, <ESC> TO EXIT.",0,0,RGB(32,32,32),lpddsback);
// flip the surfaces
DDraw_Flip();
// sync to 30ish fps
Wait_Clock(30);
// check of user is trying to exit
if (KEY_DOWN(VK_ESCAPE) || keyboard_state[DIK_ESCAPE])
{
PostMessage(main_window_handle, WM_DESTROY,0,0);
} // end if
// return success
return(1);
} // end Game_Main
int Game_Main(void *parms)
{
// this is the workhorse of your game it will be called
// continuously in real-time this is like main() in C
// all the calls for you game go here!
int index; // looping var
static int delay = 30; // initial delay per frame
// start the timing clock
DWORD start_time = Start_Clock();
// lock back buffer and copy background into it
DDraw_Lock_Back_Surface();
// draw background
Draw_Bitmap16(&background_bmp, back_buffer, back_lpitch,0);
// unlock back surface
DDraw_Unlock_Back_Surface();
// read keyboard
DInput_Read_Keyboard();
// update delay
if (keyboard_state[DIK_RIGHT])
delay+=5;
else
if (delay > 5 && keyboard_state[DIK_LEFT])
delay-=5;
// draw the ship
ship.x = ship.varsF[SHIP_X_POS]+0.5;
ship.y = ship.varsF[SHIP_Y_POS]+0.5;
ship.curr_frame = 0;
Draw_BOB(&ship, lpddsback);
// draw shadow
ship.curr_frame = 1;
ship.x-=64;
ship.y+=128;
Draw_BOB(&ship, lpddsback);
// draw the title
Draw_Text_GDI("(16-Bit Version) Time Based Kinematic Motion DEMO, Press <ESC> to Exit.",10, 10,RGB(255,255,255), lpddsback);
sprintf(buffer, "Frame rate = %f, use <RIGHT>, <LEFT> arrows to change load", 1000*1/(float)delay );
Draw_Text_GDI(buffer,10, 25,RGB(255,255,255), lpddsback);
sprintf(buffer,"Ship Velocity is %f pixels/sec",1000*ship.varsF[SHIP_X_VEL]);
Draw_Text_GDI(buffer,10, 40,RGB(255,255,255), lpddsback);
// this models the load in the game
Wait_Clock(delay);
// flip the surfaces
DDraw_Flip();
// move the ship based on time //////////////////////////////////
// x = x + v*dt
// compute dt
float dt = Get_Clock() - start_time; // in milliseconds
// move based on 30 pixels per seconds or .03 pixels per millisecond
ship.varsF[SHIP_X_POS]+=(ship.varsF[SHIP_X_VEL]*dt);
// test for off screen
if (ship.varsF[SHIP_X_POS] > screen_width+ship.width)
ship.varsF[SHIP_X_POS] = -ship.width;
//////////////////////////////////////////////////////
// check of user is trying to exit
if (KEY_DOWN(VK_ESCAPE) || keyboard_state[DIK_ESCAPE])
{
PostMessage(main_window_handle, WM_DESTROY,0,0);
// stop all sounds
DSound_Stop_All_Sounds();
} // end if
// return success
return(1);
} // end Game_Main
int Game_Main(void *parms, int num_parms)
{
// this is the workhorse of your game it will be called
// continuously in real-time this is like main() in C
// all the calls for you game go here!
int index, index_x, index_y; // looping vars
int start_map_x,start_map_y, // map positions
end_map_x,end_map_y;
int offset_x, offset_y; // pixel offsets within cell
// check of user is trying to exit
if (KEY_DOWN(VK_ESCAPE) || KEY_DOWN(VK_SPACE))
PostMessage(main_window_handle, WM_DESTROY,0,0);
// start the timing clock
Start_Clock();
// clear the drawing surface
DDraw_Fill_Surface(lpddsback, 0);
// check for movement (scrolling)
if (KEY_DOWN(VK_RIGHT))
{
if ((world_x+=4) >= 1280)
world_x = 1279;
} // end if
else
if (KEY_DOWN(VK_LEFT))
{
if ((world_x-=4) < 0)
world_x = 0;
} // end if
if (KEY_DOWN(VK_UP))
{
if ((world_y-=4) < 0)
world_y = 0;
} // end if
else
if (KEY_DOWN(VK_DOWN))
{
if ((world_y+=4) >= 896)
world_y = 895;
} // end if
// compute starting map indices by dividing position by size of cell
start_map_x = world_x/64; // use >> 6 for speed, but this is clearer
start_map_y = world_y/64;
// compute end of map rectangle for best cast i.e. aligned on 64x64 boundary
end_map_x = start_map_x + 10 - 1;
end_map_y = start_map_y + 7 - 1;
// now compute number of pixels in x,y we are within the tile, i.e
// how much is scrolled off the edge?
offset_x = -(world_x % 64);
offset_y = -(world_y % 64);
// adjust end_map_x,y for offsets
if (offset_x)
end_map_x++;
if (offset_y)
end_map_y++;
// set starting position of first upper lh texture
int texture_x = offset_x;
int texture_y = offset_y;
// draw the current window
for (index_y = start_map_y; index_y <= end_map_y; index_y++)
{
for (index_x = start_map_x; index_x <= end_map_x; index_x++)
{
// set position to blit
textures.x = texture_x;
textures.y = texture_y;
// set frame
textures.curr_frame = world[index_y][index_x] - '0';
// draw the texture
Draw_BOB(&textures,lpddsback);
// update texture position
texture_x+=64;
} // end for map_x
// reset x postion, update y
texture_x = offset_x;
texture_y += 64;
} // end for map_y
// draw some info
Draw_Text_GDI("USE ARROW KEYS TO MOVE, <ESC> to Exit.",8,8,RGB(255,255,255),lpddsback);
sprintf(buffer,"World Position = [%d, %d] ", world_x, world_y);
Draw_Text_GDI(buffer,8,screen_height - 32 - 24,RGB(0,255,0),lpddsback);
// flip the surfaces
DDraw_Flip();
// sync to 30 fps
Wait_Clock(30);
// return success
return(1);
} // end Game_Main
int Game_Main(void *parms, int num_parms)
{
// this is the workhorse of your game it will be called
// continuously in real-time this is like main() in C
// all the calls for you game go here!
int index; // looping var
// check of user is trying to exit
if (KEY_DOWN(VK_ESCAPE) || KEY_DOWN(VK_SPACE))
PostMessage(main_window_handle, WM_DESTROY,0,0);
// start the timing clock
Start_Clock();
// clear the drawing surface
DDraw_Fill_Surface(lpddsback, 0);
// get the input from the mouse
lpdimouse->GetDeviceState(sizeof(DIMOUSESTATE), (LPVOID)&mouse_state);
// move the mouse cursor
mouse_x+=(mouse_state.lX);
mouse_y+=(mouse_state.lY);
// test bounds
// first x boundaries
if (mouse_x >= screen_width)
mouse_x = screen_width-1;
else
if (mouse_x < 0)
mouse_x = 0;
// now the y boundaries
if (mouse_y >= screen_height)
mouse_y= screen_height-1;
else
if (mouse_y < 0)
mouse_y = 0;
// position the pointer bob to the mouse coords
pointer.x = mouse_x - 16;
pointer.y = mouse_y - 16;
// test what the user is doing with the mouse
if ((mouse_x > 3) && (mouse_x < 500-3) &&
(mouse_y > 3) && (mouse_y < SCREEN_HEIGHT-3))
{
// mouse is within canvas region
// if left button is down then draw
if (mouse_state.rgbButtons[0])
{
// test drawing mode
if (buttons_state[BUTTON_PENCIL])
{
// draw a pixel
Draw_Pixel(mouse_x, mouse_y, mouse_color, canvas.buffer, canvas.width);
Draw_Pixel(mouse_x+1, mouse_y, mouse_color, canvas.buffer, canvas.width);
Draw_Pixel(mouse_x, mouse_y+1, mouse_color, canvas.buffer, canvas.width);
Draw_Pixel(mouse_x+1, mouse_y+1, mouse_color, canvas.buffer, canvas.width);
}
else
{
// draw spray
for (index=0; index<10; index++)
{
// get next particle
int sx=mouse_x-8+rand()%16;
int sy=mouse_y-8+rand()%16;
// make sure particle is in bounds
if (sx > 0 && sx < 500 && sy > 0 && sy < screen_height)
Draw_Pixel(sx, sy, mouse_color, canvas.buffer, canvas.width);
} // end for index
} // end else
} // end if left button
else // right button is eraser
if (mouse_state.rgbButtons[1])
{
// test drawing mode
if (buttons_state[BUTTON_PENCIL])
{
// erase a pixel
Draw_Pixel(mouse_x, mouse_y, 0, canvas.buffer, canvas.width);
Draw_Pixel(mouse_x+1, mouse_y, 0, canvas.buffer, canvas.width);
Draw_Pixel(mouse_x, mouse_y+1, 0, canvas.buffer, canvas.width);
Draw_Pixel(mouse_x+1, mouse_y+1, 0, canvas.buffer, canvas.width);
} // end if
else
{
// erase spray
for (index=0; index<20; index++)
{
// get next particle
int sx=mouse_x-8+rand()%16;
int sy=mouse_y-8+rand()%16;
// make sure particle is in bounds
if (sx > 0 && sx < 500 && sy > 0 && sy < screen_height)
Draw_Pixel(sx, sy, 0, canvas.buffer, canvas.width);
} // end for index
} // end else
} // end if left button
} // end if
else
if ( (mouse_x > 500+16) && (mouse_x < 500+16+8*9) &&
(mouse_y > 8) && (mouse_y < 8+32*9))
{
// within palette
// test if button left button is down
if (mouse_state.rgbButtons[0])
{
// see what color cell user is pointing to
int cell_x = (mouse_x - (500+16))/9;
int cell_y = (mouse_y - (8))/9;
// change color
mouse_color = cell_x + cell_y*8;
} // end if
} // end if
else
if ((mouse_x > 500) && (mouse_x < (500+100)) &&
(mouse_y > 344) && (mouse_y < (383+34)) )
{
// within button area
// test for each button
for (index=0; index<4; index++)
{
if ((mouse_x > buttons_x[index]) && (mouse_x < (buttons_x[index]+32)) &&
(mouse_y > buttons_y[index]) && (mouse_y < (buttons_y[index]+34)) )
break;
} // end for
// at this point we know where the user is, now determine what he
// is doing with the buttons
switch(index)
{
case BUTTON_SPRAY:
{
// if left button is down simply activate spray mode
if (mouse_state.rgbButtons[0])
{
// depress button
buttons_state[index] = 1;
// de-activate pencil mode
buttons_state[BUTTON_PENCIL] = 0;
} // end if
else
{
// make sure button is up
// buttons_state[index] = 0;
} // end else
} break;
case BUTTON_PENCIL:
{
// if left button is down activate spray mode
if (mouse_state.rgbButtons[0])
{
// depress button
buttons_state[index] = 1;
// de-activate spray mode
buttons_state[BUTTON_SPRAY] = 0;
} // end if
else
{
// make sure button is up
// buttons_state[index] = 0;
} // end else
} break;
case BUTTON_ERASE:
{
// test if left button is down, if so clear screen
if (mouse_state.rgbButtons[0])
{
// clear memory
memset(canvas.buffer,0,canvas.width*canvas.height);
// depress button
buttons_state[index] = 1;
} // end if
else
{
// make sure button is up
buttons_state[index] = 0;
} // end else
} break;
case BUTTON_EXIT:
{
// test if left button down, if so bail
if (mouse_state.rgbButtons[0])
PostMessage(main_window_handle, WM_DESTROY,0,0);
} break;
} // end switch
} // end if
else
{
// no mans land
} // end else
// lock back buffer
DDraw_Lock_Back_Surface();
// draw the canvas
Draw_Bitmap(&canvas, back_buffer, back_lpitch,0);
// draw control panel
Draw_Bitmap(&cpanel,back_buffer,back_lpitch,0);
// unlock back buffer
DDraw_Unlock_Back_Surface();
// draw the color palette
for (int col=0; col < 256; col++)
{
Draw_Rectangle(500+16+(col%8)*9, 8+(col/8)*9,
500+16+(col%8)*9+8, 8+(col/8)*9+8,
col,lpddsback);
} // end for col
// draw the current color selected
Draw_Rectangle(533,306,533+34,306+34,mouse_color,lpddsback);
// draw the buttons
for (index=0; index<4; index++)
{
// set position of button bob
buttons.x = buttons_x[index];
buttons.y = buttons_y[index];
// now select the on/off frame based on if the
// button is off
if (buttons_state[index]==0)
buttons.curr_frame = index;
else // button is on
buttons.curr_frame = index+4;
// draw the button
Draw_BOB(&buttons, lpddsback);
} // end for index
static int green = 0;
// display coords
sprintf(buffer,"Pointer (%d,%d)",mouse_x,mouse_y);
Draw_Text_GDI(buffer, 8,screen_height - 16,RGB(0,255,0),lpddsback);
Draw_Text_GDI("T3D Paint Version 2.0 - Press <ESC> to Exit.",0,0,RGB(0,(green & 255),0),lpddsback);
// a little animation
++green;
// draw the cursor last
Draw_BOB(&pointer,lpddsback);
// flip the surfaces
DDraw_Flip();
// sync to 30 fps
Wait_Clock(30);
// return success
return(1);
} // end Game_Main
int Game_Main(void *parms)
{
// this is the workhorse of your game it will be called
// continuously in real-time this is like main() in C
// all the calls for you game go here!
int index; // looping var
int dx,dy; // general deltas used in collision detection
// start the timing clock
Start_Clock();
// clear the drawing surface
DDraw_Fill_Surface(lpddsback, 0);
// get the joystick data
DInput_Read_Joystick();
// lock the back buffer
DDraw_Lock_Back_Surface();
// draw the background reactor image
Draw_Bitmap(&playfield, back_buffer, back_lpitch, 0);
// unlock the back buffer
DDraw_Unlock_Back_Surface();
// is the player moving?
blaster.x+=joy_state.lX;
blaster.y+=joy_state.lY;
// test bounds
if (blaster.x > SCREEN_WIDTH-32)
blaster.x = SCREEN_WIDTH-32;
else
if (blaster.x < 0)
blaster.x = 0;
if (blaster.y > SCREEN_HEIGHT-32)
blaster.y = SCREEN_HEIGHT-32;
else
if (blaster.y < SCREEN_HEIGHT-128)
blaster.y = SCREEN_HEIGHT-128;
// is player firing?
if (joy_state.rgbButtons[0])
Start_Missile();
// move and draw missle
Move_Missile();
Draw_Missile();
// is it time to blink eyes
if ((rand()%100)==50)
Set_Animation_BOB(&blaster,0);
// draw blaster
Animate_BOB(&blaster);
Draw_BOB(&blaster,lpddsback);
// draw some text
Draw_Text_GDI("Make My Centipede!",0,0,RGB(255,255,255),lpddsback);
// display joystick and buttons 0-7
sprintf(buffer,"Joystick Stats: X-Axis=%d, Y-Axis=%d, buttons(%d,%d,%d,%d,%d,%d,%d,%d)",
joy_state.lX,joy_state.lY,
joy_state.rgbButtons[0],
joy_state.rgbButtons[1],
joy_state.rgbButtons[2],
joy_state.rgbButtons[3],
joy_state.rgbButtons[4],
joy_state.rgbButtons[5],
joy_state.rgbButtons[6],
joy_state.rgbButtons[7]);
Draw_Text_GDI(buffer,0,SCREEN_HEIGHT-20,RGB(255,255,50),lpddsback);
// print out name of joystick
sprintf(buffer, "Joystick Name & Vendor: %s",joyname);
Draw_Text_GDI(buffer,0,SCREEN_HEIGHT-40,RGB(255,255,50),lpddsback);
// flip the surfaces
DDraw_Flip();
// sync to 30 fps
Wait_Clock(30);
// check of user is trying to exit
if (KEY_DOWN(VK_ESCAPE) || keyboard_state[DIK_ESCAPE])
{
PostMessage(main_window_handle, WM_DESTROY,0,0);
} // end if
// return success
return(1);
} // end Game_Main
int Game_Main(void *parms)
{
// this is the workhorse of your game it will be called
// continuously in real-time this is like main() in C
// all the calls for you game go here!
int index; // looping var
// start the timing clock
Start_Clock();
// clear the drawing surface
DDraw_Fill_Surface(lpddsback, 0);
// lock back buffer and copy background into it
DDraw_Lock_Back_Surface();
// draw background
Draw_Bitmap(&background_bmp, back_buffer, back_lpitch,0);
// unlock back surface
DDraw_Unlock_Back_Surface();
// read keyboard
DInput_Read_Keyboard();
// check the player controls
// is the player turning right or left?
if (keyboard_state[DIK_RIGHT])
{
// there are 16 possible positions for the ship to point in
if (++ship.varsI[0] >= 16)
ship.varsI[0] = 0;
} // end if
else
if (keyboard_state[DIK_LEFT])
{
// there are 16 possible positions for the ship to point in
if (--ship.varsI[0] < 0)
ship.varsI[0] = 15;
} // end if
// now test for forward thrust
if (keyboard_state[DIK_UP])
{
// thrust ship in current direction
float rad_angle = (float)ship.varsI[0]*(float)3.14159/(float)8;
float xv = cos(rad_angle);
float yv = sin(rad_angle);
ship.varsF[0]+=xv;
ship.varsF[1]+=yv;
// animate the ship
ship.curr_frame = ship.varsI[0]+16*(rand()%2);
} // end if
else // show non thrust version
ship.curr_frame = ship.varsI[0];
// move ship
ship.varsF[2]+=ship.varsF[0];
ship.varsF[3]+=ship.varsF[1];
// always apply friction in direction opposite current trajectory
float fx = -ship.varsF[0];
float fy = -ship.varsF[1];
float length_f = sqrt(fx*fx+fy*fy); // normally we would avoid square root at all costs!
// compute the frictional resitance
if (fabs(length_f) > 0.1)
{
fx = FRICTION_FACTOR*fx/length_f;
fy = FRICTION_FACTOR*fy/length_f;
} // end if
else
fx=fy=0;
// now apply friction to forward velocity
ship.varsF[0]+=fx;
ship.varsF[1]+=fy;
////////////////////////////////////////////////////////////////////
// gravity calculation section
// step 1: compute vector from black hole to ship, note that the centers
// of each object are used
float grav_x = (black_hole.x + black_hole.width/2) - (ship.x + ship.width/2);
float grav_y = (black_hole.y + black_hole.height/2) - (ship.y + ship.height/2);
float radius_squared = grav_x*grav_x + grav_y*grav_y; // equal to radius squared
float length_grav = sqrt(radius_squared);
// step 2: normalize the length of the vector to 1.0
grav_x = grav_x/length_grav;
grav_y = grav_y/length_grav;
// step 3: compute the gravity force
float grav_force = (VIRTUAL_GRAVITY_CONSTANT) * (SHIP_MASS * BLACK_HOLE_MASS) / radius_squared;
// step 4: apply gforce in the direction of grav_x, grav_y with the magnitude of grav_force
ship.varsF[0]+=grav_x*grav_force;
ship.varsF[1]+=grav_y*grav_force;
////////////////////////////////////////////////////////////////////
// test if ship is off screen
if (ship.varsF[2] > SCREEN_WIDTH)
ship.varsF[2] = -ship.width;
else
if (ship.varsF[2] < -ship.width)
ship.varsF[2] = SCREEN_WIDTH;
if (ship.varsF[3] > SCREEN_HEIGHT)
ship.varsF[3] = -ship.height;
else
if (ship.varsF[3] < -ship.height)
ship.varsF[3] = SCREEN_HEIGHT;
// test if velocity is insane
if ( (ship.varsF[0]*ship.varsF[0] + ship.varsF[1]*ship.varsF[1]) > MAX_VEL)
{
// scale velocity down
ship.varsF[0]*=.95;
ship.varsF[1]*=.95;
} // end if
// animate the black hole
Animate_BOB(&black_hole);
// draw the black hole
Draw_BOB(&black_hole, lpddsback);
// copy floating point position to bob x,y
ship.x = ship.varsF[2];
ship.y = ship.varsF[3];
// draw the ship
Draw_BOB(&ship,lpddsback);
// draw the title
Draw_Text_GDI("GRAVITY MASS DEMO - Use Arrows to Control Ship.",10, 10,RGB(0,255,255), lpddsback);
sprintf(buffer,"Friction: X=%f, Y=%f",fx, fy);
Draw_Text_GDI(buffer,10,420,RGB(0,255,0), lpddsback);
sprintf(buffer,"Velocity: X=%f, Y=%f",ship.varsF[0], ship.varsF[1]);
Draw_Text_GDI(buffer,10,440,RGB(0,255,0), lpddsback);
sprintf(buffer,"Gravity: X=%f, Y=%f",ship.varsF[2], ship.varsF[3]);
Draw_Text_GDI(buffer,10,460,RGB(0,255,0), lpddsback);
// flip the surfaces
DDraw_Flip();
// sync to 30 fps = 1/30sec = 33 ms
Wait_Clock(33);
// check of user is trying to exit
if (KEY_DOWN(VK_ESCAPE) || keyboard_state[DIK_ESCAPE])
{
PostMessage(main_window_handle, WM_DESTROY,0,0);
// stop all sounds
DSound_Stop_All_Sounds();
// do a screen transition
Screen_Transitions(SCREEN_DARKNESS,NULL,0);
} // end if
// return success
return(1);
} // end Game_Main
