Wiki Diff allegrocreategames_robspage3, revision #1 to tip
==Robots revenge main gameplay loop
As ever in the process of game making, the player and robot entities have been added to (and will no doubt be subject to further changes, so what we have now is
<eucode>
--Robot attributes
constant R_X = 1, --x posn
R_Y = 2, --y posn
R_TYPE = 3,
R_SPEED = 4, --speed at which robot can move
R_BMP_NUM = 5, --which bitmap are we displaying
R_BMP = 6, --the actual bitmap handle
R_DIRECTION = 7, --the direction the robot travels in, use 'L' and 'R'
NUM_ROBOT_ATTRIBUTES = 7, --adjust this if you change the number of attributes
--player attributes
P_X = 1,
P_Y = 2,
P_LIFE = 3,
P_LEVEL = 4,
P_SHIELD = 5,
P_BMP_NUM = 6,
P_BMP = 7,
P_SPEED = 8,
P_DIRECTION = 9, --use 'L' and 'R'
NUM_PLAYER_ATTRIBUTES = 9,
--wall attributes
W_X = 1,
W_Y = 2,
W_BMP = 3,
W_DESTROYABLE = 4,
NUM_WALL_ATTRIBUTES = 4
</eucode>
That's right, we have also forward planned for walls!
The player and movement loop boils down to this - detect the input (in this case keys), update the player position, update the robot position, check for capture, update the arena, and update the screen.
This is encapsulated in the begin game procedure
<eucode>
---------------------------------------------------------------
procedure begin_game()
--start background music
--create arena
--populate with robots
--place exit
--place teleport if level requires it
---------------------------------------------------------------
integer fn, cn
atom arena_bmp
sequence robot_list = {}, current_robot
integer robots_per_level, num_bots, overlaid_flag = 0
sequence exit_location = {0,0}
sequence player
atom NRx, NRy --new robot position
integer player_caught = 0, at_player
atom L --distance to robot to player
--also Length of the hypotenuse
atom Pdist --the dist proportion that the robot can move
current_robot = repeat(0, NUM_ROBOT_ATTRIBUTES)
player = repeat(0, NUM_PLAYER_ATTRIBUTES)
Level = 1 --may change later
robots_per_level = 3
num_bots = Level * robots_per_level
--load intro music
fn = FMUSIC_LoadSong("action.it")
cn = FMUSIC_PlaySong(fn)
VOID = FMUSIC_SetMasterVolume(fn, 10)
arena_bmp = create_bitmap(640,480) --create a bitmap for the arena
clear_bitmap(arena_bmp) --clear the arena
--create a robot list
--Number of robots to create depends on level, for now just start with 10
robot_list = repeat(current_robot, num_bots)
for i = 1 to num_bots do
while 1 do
--robot creation incorporating anti overlaying technology
overlaid_flag = 0
robot_list[i][R_X] = rand(32) * 20 --the images are 20*20, screen size is 640 * 480, 640/20 = 32
robot_list[i][R_Y] = rand(24) * 20
for j = 1 to num_bots do --check overlays
if j = i then continue end if
if robot_list[j][R_X] = 0 then
exit
end if
if abs(robot_list[j][R_X] + 10 - robot_list[i][R_X] + 10) <= 20 or
abs(robot_list[j][R_Y] + 10 - robot_list[i][R_Y] + 10) <= 20 then
overlaid_flag = 1
exit
--try again!
end if
end for
if overlaid_flag = 0 then
exit
end if
end while
robot_list[i][R_SPEED] = 5
robot_list[i][R_TYPE] = 1
robot_list[i][R_BMP_NUM] = rand(2)
if robot_list[i][R_BMP_NUM] = 1 then
robot_list[i][R_BMP] = r1_bmp --pointers to the location of the robot bitmap
else
robot_list[i][R_BMP] = r2_bmp
end if
robot_list[i][R_DIRECTION] = 'L'
end for
--put the exit somewhere on there
while 1 do
exit_location = {rand(620), rand(460)}
overlaid_flag = 0
for i = 1 to num_bots do
if abs(robot_list[i][R_X] + 10 - exit_location[1]+10) <= 20 or
abs(robot_list[i][R_Y] + 10 - exit_location[2]+10) <= 20 then
overlaid_flag = 1
exit
--try again!
end if
end for
if overlaid_flag = 0 then
exit
end if
end while
--set up the player
while 1 do
player[P_X] = rand(620)
player[P_Y] = rand(480)
player[P_SPEED] = 7
overlaid_flag = 0
for i = 1 to num_bots do
if abs(robot_list[i][R_X] + 10 - player[P_X]+10) <= 20 or
abs(robot_list[i][R_Y] + 10 - player[P_Y]+10) <= 20 then
overlaid_flag = 1
exit
--try again!
end if
end for
if overlaid_flag = 0 then
exit
end if
end while
player[P_LIFE] = 3
player[P_LEVEL] = Level
player[P_SHIELD] = 0
player[P_BMP_NUM] = 1
if player[P_BMP_NUM] = 1 then
player[P_BMP] = p1_bmp
else
player[P_BMP] = p2_bmp
end if
player[P_DIRECTION] = 'L'
--that's the robots, the exit and the player set up
--lets blit them onto the arena bitmap, then blit that to the screen.
for i = 1 to num_bots do
blit(robot_list[i][R_BMP], arena_bmp, --src_bmp, dest_bmp
0,0, --src start coords
robot_list[i][R_X],robot_list[i][R_Y], --dest coords
20,20) --size of src to blit
end for
--blit the exit somewhere on there
blit(exit_bmp, arena_bmp,
0,0,
exit_location[1], exit_location[2],
20,20)
--blit the player on to the arena
blit(player[P_BMP], arena_bmp,
0,0,
player[P_X], player[P_Y],
20,20)
blit(arena_bmp, screen, 0, 0, 0, 0, SCREEN_W, SCREEN_H)
--player and robot movement loop
while 1 do
--wait for a cursor key to be pressed
--while keypressed() = 0 do end while
clear_keybuf()
VOID = readkey()
if key(KEY_UP) then
player[P_Y] -= player[P_SPEED]
if player[P_Y] < 0 then
player[P_Y] = 1
end if
elsif key(KEY_DOWN) then
player[P_Y] += player[P_SPEED]
if player[P_Y] > SCREEN_H - 20 then
player[P_Y] = SCREEN_H - 20
end if
elsif key(KEY_LEFT) then
player[P_X] -= player[P_SPEED]
if player[P_X] < 0 then
player[P_X] = 1
end if
player[P_DIRECTION] = 'L'
elsif key(KEY_RIGHT) then
player[P_X] += player[P_SPEED]
if player[P_X] > SCREEN_W - 20 then
player[P_X] = SCREEN_W - 20
end if
player[P_DIRECTION] = 'R'
elsif key(KEY_Q) or key(KEY_ESC) then
exit
end if
--animate the player
player[P_BMP_NUM] = player[P_BMP_NUM] * -1 + 1
if player[P_BMP_NUM] = 1 then
player[P_BMP] = p1_bmp
else
player[P_BMP] = p2_bmp
end if
--update the arena bmp
clear_bitmap(arena_bmp) --this is just one way of doing this
--could clear each of the old bitmaps,
--and write the new ones
/*
for i = 1 to num_bots do
blit(robot_list[i][R_BMP], arena_bmp, --src_bmp, dest_bmp
0,0, --src start coords
robot_list[i][R_X],robot_list[i][R_Y], --dest coords
20,20) --size of src to blit
end for
*/
--blit the exit somewhere on there
blit(exit_bmp, arena_bmp,
0,0,
exit_location[1], exit_location[2],
20,20)
--blit the player on to the arena
--note using draw sprite here, so we can flip the bmp
if player[P_DIRECTION] = 'L' then
draw_sprite(arena_bmp, player[P_BMP], --destination, src
player[P_X], player[P_Y]) --position
else
draw_sprite_h_flip(arena_bmp, player[P_BMP], --destination, src
player[P_X], player[P_Y]) --position
end if
--blit(player[P_BMP], arena_bmp,
-- 0,0,
-- player[P_X], player[P_Y],
-- 20,20)
--move and animate each of the bots
for i = 1 to num_bots do
at_player = 0
L = sqrt(power(robot_list[i][R_X] - player[P_X], 2) + power(robot_list[i][R_Y] - player[P_Y], 2))
--L = the length of the hypotenuse
Pdist = robot_list[i][R_SPEED] / L
if Pdist > 1 then
player_caught = 1
at_player = 1
end if
NRx = robot_list[i][R_X] - (robot_list[i][R_X] - player[P_X]) * Pdist
NRy = robot_list[i][R_Y] - (robot_list[i][R_Y] - player[P_Y]) * Pdist
if at_player = 1 then
NRx = player[P_X]
NRy = player[P_Y]
end if
--animate the robot
if robot_list[i][R_BMP_NUM] = 1 then
robot_list[i][R_BMP_NUM] = 0
robot_list[i][R_BMP] = r1_bmp --pointers to the location of the robot bitmap
else
robot_list[i][R_BMP_NUM] = 1
robot_list[i][R_BMP] = r2_bmp
end if
if NRx < robot_list[i][R_X] then
robot_list[i][R_DIRECTION] = 'L'
else
robot_list[i][R_DIRECTION] = 'R'
end if
--update the robot position
robot_list[i][R_X] = floor(NRx)
robot_list[i][R_Y] = floor(NRy)
--draw the robot sprites to the arena
if robot_list[i][R_DIRECTION] = 'L' then
draw_sprite(arena_bmp, robot_list[i][R_BMP], --destination, src
robot_list[i][R_X], robot_list[i][R_Y]) --position
else
draw_sprite_h_flip(arena_bmp, robot_list[i][R_BMP], --destination, src
robot_list[i][R_X], robot_list[i][R_Y]) --position
end if
end for
blit(arena_bmp, screen, 0, 0, 0, 0, SCREEN_W, SCREEN_H)
rest(100)
end while
VOID = FMUSIC_StopSong(fn)
VOID = FMUSIC_FreeSong(fn)
end procedure
</eucode>
The code is well commented, so there isn't much point in me adding much here.\\
\\
The 'which direction should the robot move in' section is interesting, in that this introduces some vector maths. I had to work this out for myself again, so it was an interesting excercise for me too.\\
\\
The allegro screen starts in the top left at pixel 1,1, x goes along the top of the screen from left to right up to 640 (or chosen resolution), and from top to bottom to 480 (or chosen resolution).\\
\\
I wanted to move the robot towards the player at it's attributed speed. so the first thing to do was to calculate the length of the vector, or line, between the player and the robot.\\
\\
The player is at coordinates Px and Py, and the robot at coordinates Rx and Ry. This actually forms a right angled triangle which we use to calculate the length of the hypoteneuse, that looks like this\\
\\
%(
{{https://drive.google.com/file/d/0B_FlaOPLFXdTTC1yZ1BXczdrSDA/view?usp=sharing}}
)%
(Can't get this to embed yet)\\
Once we have the length of the hypotenuse, we can work out the proportion of that the robot will travel towards the player in it's speed allocation - Length / speed. Note, if this is greater than one then the robot has overtaken the player.\\
\\
Next we use this proportion to update the x and y coordinates of the robot, as a proportion along the x and y axis differences between the robot position and the player position. (see NRx and NRy in the code)\\
\\
We also introduce draw_sprite() and draw_sprite_h_flip() - these are simpler ways of putting the robot bitmap onto the arena (treating the bitmap as a sprite). As the backgrounds of the sprite is the same colour as the arena, we don't need to worry about sprite colour transparency, just yet, but look what happens when the bitmaps overlay each other. We use draw_sprite_h_flip() because it flips the bitmap to make it look like its going in a different direction.\\
\\
Player capture is covered - we just need an end animation. Player exit isn't detected, and next levels aren't done yet. I'm going to make this a bit tidier for the next iteration, but for now you can download the program from [[https://app.box.com/s/c8w99wcdknep0bwh27lxneg2cscc40fc]] (Its RobotsR02.exw - just run this in the same folder as all the other media)
\\
[[http://openeuphoria.org/wiki/view/allegro.wc|Home]]\\
[[http://openeuphoria.org/wiki/view/allegrocreategames_robspage4.wc|Page 4 - clash detection]]
As ever in the process of game making, the player and robot entities have been added to (and will no doubt be subject to further changes, so what we have now is
<eucode>
--Robot attributes
constant R_X = 1, --x posn
R_Y = 2, --y posn
R_TYPE = 3,
R_SPEED = 4, --speed at which robot can move
R_BMP_NUM = 5, --which bitmap are we displaying
R_BMP = 6, --the actual bitmap handle
R_DIRECTION = 7, --the direction the robot travels in, use 'L' and 'R'
NUM_ROBOT_ATTRIBUTES = 7, --adjust this if you change the number of attributes
--player attributes
P_X = 1,
P_Y = 2,
P_LIFE = 3,
P_LEVEL = 4,
P_SHIELD = 5,
P_BMP_NUM = 6,
P_BMP = 7,
P_SPEED = 8,
P_DIRECTION = 9, --use 'L' and 'R'
NUM_PLAYER_ATTRIBUTES = 9,
--wall attributes
W_X = 1,
W_Y = 2,
W_BMP = 3,
W_DESTROYABLE = 4,
NUM_WALL_ATTRIBUTES = 4
</eucode>
That's right, we have also forward planned for walls!
The player and movement loop boils down to this - detect the input (in this case keys), update the player position, update the robot position, check for capture, update the arena, and update the screen.
This is encapsulated in the begin game procedure
<eucode>
---------------------------------------------------------------
procedure begin_game()
--start background music
--create arena
--populate with robots
--place exit
--place teleport if level requires it
---------------------------------------------------------------
integer fn, cn
atom arena_bmp
sequence robot_list = {}, current_robot
integer robots_per_level, num_bots, overlaid_flag = 0
sequence exit_location = {0,0}
sequence player
atom NRx, NRy --new robot position
integer player_caught = 0, at_player
atom L --distance to robot to player
--also Length of the hypotenuse
atom Pdist --the dist proportion that the robot can move
current_robot = repeat(0, NUM_ROBOT_ATTRIBUTES)
player = repeat(0, NUM_PLAYER_ATTRIBUTES)
Level = 1 --may change later
robots_per_level = 3
num_bots = Level * robots_per_level
--load intro music
fn = FMUSIC_LoadSong("action.it")
cn = FMUSIC_PlaySong(fn)
VOID = FMUSIC_SetMasterVolume(fn, 10)
arena_bmp = create_bitmap(640,480) --create a bitmap for the arena
clear_bitmap(arena_bmp) --clear the arena
--create a robot list
--Number of robots to create depends on level, for now just start with 10
robot_list = repeat(current_robot, num_bots)
for i = 1 to num_bots do
while 1 do
--robot creation incorporating anti overlaying technology
overlaid_flag = 0
robot_list[i][R_X] = rand(32) * 20 --the images are 20*20, screen size is 640 * 480, 640/20 = 32
robot_list[i][R_Y] = rand(24) * 20
for j = 1 to num_bots do --check overlays
if j = i then continue end if
if robot_list[j][R_X] = 0 then
exit
end if
if abs(robot_list[j][R_X] + 10 - robot_list[i][R_X] + 10) <= 20 or
abs(robot_list[j][R_Y] + 10 - robot_list[i][R_Y] + 10) <= 20 then
overlaid_flag = 1
exit
--try again!
end if
end for
if overlaid_flag = 0 then
exit
end if
end while
robot_list[i][R_SPEED] = 5
robot_list[i][R_TYPE] = 1
robot_list[i][R_BMP_NUM] = rand(2)
if robot_list[i][R_BMP_NUM] = 1 then
robot_list[i][R_BMP] = r1_bmp --pointers to the location of the robot bitmap
else
robot_list[i][R_BMP] = r2_bmp
end if
robot_list[i][R_DIRECTION] = 'L'
end for
--put the exit somewhere on there
while 1 do
exit_location = {rand(620), rand(460)}
overlaid_flag = 0
for i = 1 to num_bots do
if abs(robot_list[i][R_X] + 10 - exit_location[1]+10) <= 20 or
abs(robot_list[i][R_Y] + 10 - exit_location[2]+10) <= 20 then
overlaid_flag = 1
exit
--try again!
end if
end for
if overlaid_flag = 0 then
exit
end if
end while
--set up the player
while 1 do
player[P_X] = rand(620)
player[P_Y] = rand(480)
player[P_SPEED] = 7
overlaid_flag = 0
for i = 1 to num_bots do
if abs(robot_list[i][R_X] + 10 - player[P_X]+10) <= 20 or
abs(robot_list[i][R_Y] + 10 - player[P_Y]+10) <= 20 then
overlaid_flag = 1
exit
--try again!
end if
end for
if overlaid_flag = 0 then
exit
end if
end while
player[P_LIFE] = 3
player[P_LEVEL] = Level
player[P_SHIELD] = 0
player[P_BMP_NUM] = 1
if player[P_BMP_NUM] = 1 then
player[P_BMP] = p1_bmp
else
player[P_BMP] = p2_bmp
end if
player[P_DIRECTION] = 'L'
--that's the robots, the exit and the player set up
--lets blit them onto the arena bitmap, then blit that to the screen.
for i = 1 to num_bots do
blit(robot_list[i][R_BMP], arena_bmp, --src_bmp, dest_bmp
0,0, --src start coords
robot_list[i][R_X],robot_list[i][R_Y], --dest coords
20,20) --size of src to blit
end for
--blit the exit somewhere on there
blit(exit_bmp, arena_bmp,
0,0,
exit_location[1], exit_location[2],
20,20)
--blit the player on to the arena
blit(player[P_BMP], arena_bmp,
0,0,
player[P_X], player[P_Y],
20,20)
blit(arena_bmp, screen, 0, 0, 0, 0, SCREEN_W, SCREEN_H)
--player and robot movement loop
while 1 do
--wait for a cursor key to be pressed
--while keypressed() = 0 do end while
clear_keybuf()
VOID = readkey()
if key(KEY_UP) then
player[P_Y] -= player[P_SPEED]
if player[P_Y] < 0 then
player[P_Y] = 1
end if
elsif key(KEY_DOWN) then
player[P_Y] += player[P_SPEED]
if player[P_Y] > SCREEN_H - 20 then
player[P_Y] = SCREEN_H - 20
end if
elsif key(KEY_LEFT) then
player[P_X] -= player[P_SPEED]
if player[P_X] < 0 then
player[P_X] = 1
end if
player[P_DIRECTION] = 'L'
elsif key(KEY_RIGHT) then
player[P_X] += player[P_SPEED]
if player[P_X] > SCREEN_W - 20 then
player[P_X] = SCREEN_W - 20
end if
player[P_DIRECTION] = 'R'
elsif key(KEY_Q) or key(KEY_ESC) then
exit
end if
--animate the player
player[P_BMP_NUM] = player[P_BMP_NUM] * -1 + 1
if player[P_BMP_NUM] = 1 then
player[P_BMP] = p1_bmp
else
player[P_BMP] = p2_bmp
end if
--update the arena bmp
clear_bitmap(arena_bmp) --this is just one way of doing this
--could clear each of the old bitmaps,
--and write the new ones
/*
for i = 1 to num_bots do
blit(robot_list[i][R_BMP], arena_bmp, --src_bmp, dest_bmp
0,0, --src start coords
robot_list[i][R_X],robot_list[i][R_Y], --dest coords
20,20) --size of src to blit
end for
*/
--blit the exit somewhere on there
blit(exit_bmp, arena_bmp,
0,0,
exit_location[1], exit_location[2],
20,20)
--blit the player on to the arena
--note using draw sprite here, so we can flip the bmp
if player[P_DIRECTION] = 'L' then
draw_sprite(arena_bmp, player[P_BMP], --destination, src
player[P_X], player[P_Y]) --position
else
draw_sprite_h_flip(arena_bmp, player[P_BMP], --destination, src
player[P_X], player[P_Y]) --position
end if
--blit(player[P_BMP], arena_bmp,
-- 0,0,
-- player[P_X], player[P_Y],
-- 20,20)
--move and animate each of the bots
for i = 1 to num_bots do
at_player = 0
L = sqrt(power(robot_list[i][R_X] - player[P_X], 2) + power(robot_list[i][R_Y] - player[P_Y], 2))
--L = the length of the hypotenuse
Pdist = robot_list[i][R_SPEED] / L
if Pdist > 1 then
player_caught = 1
at_player = 1
end if
NRx = robot_list[i][R_X] - (robot_list[i][R_X] - player[P_X]) * Pdist
NRy = robot_list[i][R_Y] - (robot_list[i][R_Y] - player[P_Y]) * Pdist
if at_player = 1 then
NRx = player[P_X]
NRy = player[P_Y]
end if
--animate the robot
if robot_list[i][R_BMP_NUM] = 1 then
robot_list[i][R_BMP_NUM] = 0
robot_list[i][R_BMP] = r1_bmp --pointers to the location of the robot bitmap
else
robot_list[i][R_BMP_NUM] = 1
robot_list[i][R_BMP] = r2_bmp
end if
if NRx < robot_list[i][R_X] then
robot_list[i][R_DIRECTION] = 'L'
else
robot_list[i][R_DIRECTION] = 'R'
end if
--update the robot position
robot_list[i][R_X] = floor(NRx)
robot_list[i][R_Y] = floor(NRy)
--draw the robot sprites to the arena
if robot_list[i][R_DIRECTION] = 'L' then
draw_sprite(arena_bmp, robot_list[i][R_BMP], --destination, src
robot_list[i][R_X], robot_list[i][R_Y]) --position
else
draw_sprite_h_flip(arena_bmp, robot_list[i][R_BMP], --destination, src
robot_list[i][R_X], robot_list[i][R_Y]) --position
end if
end for
blit(arena_bmp, screen, 0, 0, 0, 0, SCREEN_W, SCREEN_H)
rest(100)
end while
VOID = FMUSIC_StopSong(fn)
VOID = FMUSIC_FreeSong(fn)
end procedure
</eucode>
The code is well commented, so there isn't much point in me adding much here.\\
\\
The 'which direction should the robot move in' section is interesting, in that this introduces some vector maths. I had to work this out for myself again, so it was an interesting excercise for me too.\\
\\
The allegro screen starts in the top left at pixel 1,1, x goes along the top of the screen from left to right up to 640 (or chosen resolution), and from top to bottom to 480 (or chosen resolution).\\
\\
I wanted to move the robot towards the player at it's attributed speed. so the first thing to do was to calculate the length of the vector, or line, between the player and the robot.\\
\\
The player is at coordinates Px and Py, and the robot at coordinates Rx and Ry. This actually forms a right angled triangle which we use to calculate the length of the hypoteneuse, that looks like this\\
\\
%(
{{https://drive.google.com/file/d/0B_FlaOPLFXdTTC1yZ1BXczdrSDA/view?usp=sharing}}
)%
(Can't get this to embed yet)\\
Once we have the length of the hypotenuse, we can work out the proportion of that the robot will travel towards the player in it's speed allocation - Length / speed. Note, if this is greater than one then the robot has overtaken the player.\\
\\
Next we use this proportion to update the x and y coordinates of the robot, as a proportion along the x and y axis differences between the robot position and the player position. (see NRx and NRy in the code)\\
\\
We also introduce draw_sprite() and draw_sprite_h_flip() - these are simpler ways of putting the robot bitmap onto the arena (treating the bitmap as a sprite). As the backgrounds of the sprite is the same colour as the arena, we don't need to worry about sprite colour transparency, just yet, but look what happens when the bitmaps overlay each other. We use draw_sprite_h_flip() because it flips the bitmap to make it look like its going in a different direction.\\
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Player capture is covered - we just need an end animation. Player exit isn't detected, and next levels aren't done yet. I'm going to make this a bit tidier for the next iteration, but for now you can download the program from [[https://app.box.com/s/c8w99wcdknep0bwh27lxneg2cscc40fc]] (Its RobotsR02.exw - just run this in the same folder as all the other media)
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