Decoded: Sopwith (1984) by David L. Clark Source file: SWMOVE.C Beginner friendly, line-by-line code walkthrough by MaiZure SWMOVE.C manages user input and executes actions Original code: http://davidlclark.com/page/sopwith-source-code Original code with line numbers http://www.maizure.org/projects/decoded-sopwith/SWMOVE_linenum.txt 1 COMMENT 2 COMMENT 3 BLANK 4 COMMENT 5 COMMENT 6 COMMENT 7 COMMENT 8 COMMENT 9 COMMENT 10 COMMENT 11 COMMENT 12 COMMENT 13 COMMENT 14 BLANK 15 COMMENT 16 BLANK 17 COMMENT 18 COMMENT 19 COMMENT 20 COMMENT 21 COMMENT 22 COMMENT 23 COMMENT 24 COMMENT 25 COMMENT 26 COMMENT 27 COMMENT 28 COMMENT 29 COMMENT 30 COMMENT 31 COMMENT 32 COMMENT 33 Include the main game header (sw.h) 34 BLANK 35 BLANK 36 BLANK 37 Import the display boundary locations from SWMAIN.C 38 Import the display shift amount SWMAIN.C 39 Import object pointer to the top of the object list 40 Import object pointer to the first element of the free object list 41 Import object pointer to both ends of the delete list 42 Import plane object list 43 Import other object list 44 Import the computer plane pointer arrays 45 Import the left computer territory array 46 Import the right computer territory array 47 Import the game play mode from SWMAIN.C 48 Import the multiplayer communication buffer 49 Import the sine table 50 Import the ground height array 51 Import the keydelay setting 52 Import the multiplayer key buffer 53 Import the plane graphic 54 Import the crashing plane graphic 55 Import the bomb graphic 56 Import the missile graphic 57 Import the flare graphic 58 Import the building graphics 59 Import the plane playing away graphics 60 Import the broken building graphic 61 Import the explosion graphics 62 Import the bird flock graphics 63 Import the bird graphics 64 Import the ox graphics 65 Import a display function 66 Import the performance counters 67 Import the flag for computer plane movement 68 Import the flag for player plane movement 69 Import the current object index 70 Import the player object index 71 Import the sound on/off fralg 72 Import the end game status of players 73 Import the end game counter 74 Import the victory flag 75 Import the current game number (used for difficulty) 76 Import the game speed boundaries 77 Import the maximum target range value 78 Import the keyboard couner 79 Import the end game status 80 BLANK 81 Import the missiles enabled flag 82 BLANK 83 Import the quit flag 84 BLANK 85 BLANK 86 BLANK 87 BLANK MOVE ALL OBJECTS 88 Declare and define swmove with no arguments 89 BLOCK START - swmove, main update loop for all objects 90 Declares two local object pointers 91 BLANK 92 BLOCK START - handle recently deleted objects, deleted object pending? 93 Point the end of the list to the free list 94 Make the free list the top of the delete list 95 Remove the delete list 96 BLOCK END - handle recently deleted objects 97 BLANK 98 If the input counter has exceed the keydelay threshold.. 99 Reset the counter to 0 100 BLANK 101 Point to the first object in the game 102 BLOCK START - process all objects for movement 103 Set the second pointer to the next object 104 Cycle the draw flag to the delete flag (cycling XOR drawing efforts) 105 Move the current graphic to the old graphic 106 Peforms the move function for the object and saves the result 107 If we're in a multiplayer game... 108 and this is another player's plane... 109 ...and we've reached the proper delay point.. 110 Check if we're in a direct multiplayer and... 111 Send the move command to the multiplayer interface 112 Otherwise we're in an asynchronous game so... 113 Send the move to the asynchonous interface.. 114 Update our current object pointer to the next object 115 BLOCK END - process all objects for movement 116 Iterate our move/tick counter 117 BLANK 118 BLOCK END - swmove 119 BLANK 120 BLANK 121 BLANK MOVE PLAYER 122 Declare and define moveplyr with one argument 123 Argument one is a pointer to the player plane 124 BLOCK START - moveplyr, moves the player plane 125 Declares a local object pointer 126 Declare a return flag 127 Declare a temporary old x value 128 BLANK 129 Set the computer plane global to false (now processing player) 130 Set the player plane global to true (this matters for call to movepln) 131 BLANK 132 Point to the input plane 133 Get the input plane's index 134 BLANK 135 BLOCK START - check for player game over, if endstat is set.. 136 ...and if the end game counter has reached zero.. 137 Then we're not in network multiplayer 138 or not in asynchronous multipler 139 and haven't chosen to quit... 140 Then restart the game 141 Otherwise, the multiplayer game is over so end the game 142 BLOCK END - check for player game over 143 BLANK 144 BLOCK START - keyboard delay check, if the delay has ended.. 145 If we're in multiplayer.. 146 Get the multiplayer's key input 147 Or in asynch mode 148 Get the key from the asynch file 149 Otherwise, we're in single player so.. 150 Read the keyboard buffer 151 Then flush the keyboard buffer 152 End case for play mode check 153 Apply the key read to the plane 154 Otherwise, the delay continues.. 155 Change the plane flaps to neutral 156 Undo bombing actions (no carpet bombing) 157 Undo shooting actions (no automatic weapons) 158 BLOCK END - keyboard delay check 159 BLANK 160 If the player plane has crashed... 161 And the hitcount is zero.. 162 Increment player's crash counter 163 If the player hasn't won... 164 and the life value is below -5000 (possible?? long multiplayer delay?) 165 Or the playmode isn't multiplayer 166 ...play mode isn't asynch 167 ...crashed too much.. 168 And the end state hasn't been set 169 Then this guy obviously lost 170 Otherwise, the player did win 171 Reinitialize the player 172 and the bottom HUD 173 Double check the end state.. 174 Unless player hit control break, in that case 175 End the game 176 Otherwise, show the win sequence 177 End case for player win 2 178 End case for player win 179 End case for crashed plane 180 BLANK 181 Save the player's previous location 182 Move the plane and save the state (Alive or not) 183 If the plane is within the screen boundary 184 Then reset screen scrolling 185 Otherwise, the plane has moved too close to the ends 186 Update left screen boundary by the rate of movement of the plane 187 Update right screen boundary by the rate of movement of the plane 188 End case for crashed plane 189 BLANK 190 BLOCK START - update HUD, if the player isn't at home... 191 Set the active video segment 192 If the player is firing... 193 Update the ammo counter 194 If the player is bombing... 195 Update the bomb counter 196 If the player is firing missiles... 197 Update the missile counter 198 If the player is dropping flares... 199 Update the falre counter 200 BLOCK END - update HUD 201 BLANK 202 Return the player's state (still alive or not) 203 BLOCK END - moveplyr 204 BLANK 205 BLANK 206 BLANK 207 BLANK HANDLE KEYBOARD COMMANDS 208 Declare and define interpret with two arguments 209 Argument 1 is a pointer to the input player plane 210 Argument 2 is the key pressed 211 BLOCK START - interpret, applies keyboard input to the player plane 212 Declares a local object pointer 213 Declares a local state variable 214 BLANK 215 Points to the input object, usually player's plane 216 Sets turning state to 0 217 Resets bombing state 218 Reset shooting state 219 If no valid state to receive input...not in flying move 220 ...nor stalled 221 ...nor falling 222 ...nor wounded 223 ...nor stalled and wounded 224 ...nor a ghost 225 ...nor a stalled ghost 226 Then return from interpret -- nothing to do 227 BLANK 228 BLOCK START - Non-falling plane input 229 If an ending has been reached 230 And the ending is loser and while play is still alive... 231 Then have the plane return to base 232 Return form interpret -- nothing to do 233 End case for ending 234 BLANK 235 BLOCK START - Break key pressed, if break was pressed 236 Set the player's life counter to quit 237 Set going home to false 238 If the player is already at home... 239 And the state is already finished... 240 Set state to crashed (or some form of it) 241 Reset the hit counter 242 End case for plane at home 243 If the player is still active.. 244 Then set the global quit flag to true -- shutdown on next game loop 245 BLOCK END - Break key pressed 246 BLANK 247 If the player hit the key to fly home... 248 Then if the player is flying.. 249 Or a ghost.. 250 Or wounded... 251 Then set the home flag to true (plane autopilots home) 252 BLOCK END - Non-falling plane input 253 BLANK 254 On every odd count of the game counter... 255 Or if the player isn't wounded..(wounded slows reactions) 256 Then if the player moves the flaps up.. 257 Move the flaps 258 Player is no longer at home (instant takeoff!) 259 End case for move flaps up 260 BLANK 261 If the player moves the flaps down.. 262 Move the flaps 263 Set the player to not at home (instant death!) 264 End case for move flaps down 265 BLANK 266 If the player hit's the key to flip the plane... 267 Then flip it! (invert orientation variable) 268 Player is no longer at home (not instant death, but it should be) 269 End case for flip 270 BLANK 271 Player cuts the engines a bit 272 If the plane had some power... 273 Reduce it a bit 274 The player is no longer at home 275 End case for deceleration 276 BLANK 277 If the player opens the throttle 278 Then if the plane isn't already at max speed 279 Increase the plane's acceleration 280 Plane is no longer at home base 281 End case for speed up 282 End case for wounded plane behavior 283 BLANK 284 If the player pulls the trigger and the game hasn't ended... 285 Then set the variable to fire (processed later) 286 BLANK 287 If the player tries to fire a missile and the game hasn't ended.. 288 Set the fire missile flag 289 BLANK 290 If the player pulls the bomb drop lever and the game is still on... 291 Then set the bomb drop flag for layer processing 292 BLANK 293 If the flare presses the flare key and the game is still in progress 294 Then set the flare drop flag 295 BLANK 296 If the player turns the sound off 297 Then if the player is still active.. 298 And there is currently a sound playing... 299 Set the sound to null (no sound) 300 Swap null sound to current sound 301 End case for sound in progress 302 Toggle the sound flag 303 End case for player in progress 304 BLANK 305 If the object's home flag is now set then... 306 Execute return to base for the object 307 BLOCK END - interpret 308 BLANK 309 BLANK 310 BLANK MOVE COMPUTER PLANES 311 Declares and defines movecomp with one argument 312 Argument 1 is a pointer to an input plane 313 BLOCK START - movecomp, moves a computer plane 314 Declares a local object pointer 315 BLANK 316 Set the global computer player flag to true 317 Set the global human player flag to false 318 BLANK 319 Point to the input object 320 Reset the flap (turning) state to neutral 321 Reset bomb drop states 322 Reset missile firing states 323 BLANK 324 Pull the current end state for the object 325 BLANK 326 If the delay counter has expired 327 Then disable bullet firing 328 BLANK 329 SWITCH on computer plane state 330 BLANK 331 CASE wounded (fall-through) 332 CASE wounded and stalled 333 Don't process input if we're on an odd turn count (slow reactions) 334 End switch 335 BLANK 336 CASE flying (fall-through) 337 CASE stalled (fall-through) 338 If the game is in an end state... 339 Then always return home 340 End switch 341 End check for end game 342 If the input counter has expired... 343 Pass the flying decision to the AI routine in SWAUTO.C 344 End switch 345 BLANK 346 CASE crashed 347 Plane should no longer be firing 348 If hitcounter is 0 or lower and the game hasn't ended 349 Reinitialize the computer plane at home base 350 End switch 351 BLANK 352 In all cases... 353 Disable plane firing 354 End switch 355 End switch 356 BLANK 357 Call general plane actions using flags that are set and return state 358 BLOCK END - movecomp 359 BLANK 360 BLANK 361 BLANK MOVE PLANES (GENERIC) 362 Declares and defines movepln with one argument 363 Argument 1 is an input plane 364 BLOCK START - movepln, applies generic move actions to all planes 365 Declares a local object pointer 366 Declare local variables for plane movement properties 367 Declare local variables for plane positions 368 Declare a gravity effects indexed by the first 8 game angles... 369 ...and the second 8 game angles 370 BLANK 371 Point to the input plane 372 BLOCK START - SWITCH on plane state 373 CASE plane is finished (fall-through) 374 CASE plane is waiting 375 Nothing to display, return false 376 BLANK 377 CASE plane is crashed (fall-through) 378 CASE plane is a ghost and still crashed 379 Decrement the hit counter 380 End switch -- nothing else to do 381 BLANK 382 CASE plane is falling 383 Decrement the high counter by 2 384 If the plane is falling while moving foward... 385 And the plane is moving upside down... 386 Decrement the hit counter (positive flaps) 387 Otherwise it's right side up 388 Decrement the hit counter once more (negative flaps) 389 BLANK 390 If the his counter is 0 or negative 391 and the plane is moving downwards 392 And to the left 393 Decrease leftward movement 394 Otherwise if it's moving right 395 Decrease rightward movement 396 Otherwise it's falling straight down... 397 Just roll the plane 398 BLANK 399 If the plane is falling slower than 10 pixels per tick 400 Apply more gravity 401 Reset the hit counter 402 End case for end of hit counter cycle 403 Update the object's angle (double return for the games 16 base angles) 404 If the plane is moving downward 405 Start the plane's falling sound 406 End case plane falling 407 BLANK 408 CASE plane is staled 409 Set the return state to flying 410 Go to stall subproc on line 419 411 BLANK 412 CASE plane is a ghost and stalled 413 Set the return state to ghost 414 Go to stall subproc on line 419 415 BLANK 416 CASE plane is wounded and stalled 417 Set the return state to wounded 418 BLANK 419 Stall handler sub-procedure 420 If the plane s no longer falling... 421 And the plane is no long moving below minimum speed.. 422 Then return plane to previous flight mode 423 Go to controlled flight procedure on line 438 424 BLANK 425 CASE plane is flying normally (fall-through) 426 CASE plane is wounded (fall-through) 427 CASE plane is a ghost 428 If the plane is stalled but the plane is off the top of the screen.. 429 And the difficulty is novice.. 430 Set the plane angle to downward 431 Unstall the plane 432 Otherwise we're in expert mode... 433 Stall the plane 434 Save the state 435 End check for expert 436 End check for stalled 437 BLANK 438 Controlled flight sub-procedure 439 If the player has already won... 440 Nothing to do, skip movement 441 BLANK 442 If the plane life is 0 and we're not at home.. 443 and we're flying normally... 444 ...or stalled... 445 ...or wounded... 446 ...or both... 447 Then hit the plane 448 Add some score 449 Return a recusrive call to movement 450 End case for no life 451 BLANK 452 If the plane is firing 453 Create a shot 454 BLANK 455 If the plane is dropping a bomb 456 Then make a bomb 457 BLANK 458 If the plane is firing a missile 459 Create the missile 460 BLANK 461 If the plane is dropping a flare 462 Make the flare 463 BLANK 464 Store the current angle 465 Store the current speed 466 Set update to false 467 BLANK 468 If the flaps are engaged... 469 and the plane is inverted... 470 Decrease the stored angle (more falling) 471 Otherwise... 472 Increase the stored angle (more falling) 473 Wrap the angle if necessary 474 End case for updates 475 BLANK 476 Every 4 ticks, we'll update speed... 477 If the plane isn't stalled but the plane is travelling slow.. 478 and we're in expert mode.. 479 Decrease speed even more 480 Set update flag (triggers line 495) 481 Otherwise... 482 Save the current speed limit... (varies on game difficulty) 483 plus the speed of the plane... 484 plus the gravity/angle offset...(we go faster downwards) 485 If the speed is below the limit.. 486 Boost speed 487 And set update 488 Otherwise, if the speed is too fast 489 decrease speed 490 and set update flag anyway 491 End check for speeding 492 End check for stalled 493 End check for every 4 tick check 494 BLANK 495 If the update flag was set above... 496 If we're parked at the air base 497 And if we're accelerating or trying to fly.. 498 Save speed at minimum 499 Otherwise.. 500 No speed 501 BLANK 502 Otherwise, we're not at home so if we're slow and not stalled... 503 But we're novice.. 504 Just give the player free speed 505 But if we're on expert.. 506 Stall the plane 507 Recursively update move 508 End check for expert stall 509 End check for not at home 510 BLANK 511 Set the plane speed to the speed we've calculated above 512 Set the plane angle to the calculated angle 513 BLANK 514 If the plane is stalled 515 Reset all tracking vectors 516 Negate the speed 517 Otherwise, 518 Update the object's motion... 519 With the x vector 520 and the y vector 521 End motion update 522 End update check 523 BLANK 524 If the plane is stalled... 525 If the decremented hit counter is 0 526 Spin the plane 527 Point the plane downward... 528 Less the actual angle.. 529 Wrap if necessary 530 Set the hit counter to the stall counter 531 Ene check for hit counter update 532 End check for called 533 BLANK 534 If this isn't a computer plane... 535 And if the player is still around... 536 And the player's speed is greater than... 537 ...the life counter mod 900 538 Set the display segment to video memory 539 Update the fuel guage on the HUD 540 End case for player fuel update 541 Tick the life counter by the speed 542 End case for player plane 543 BLANK 544 If the plane is moving... 545 Then it can't be at home 546 End case for normal flight modes 547 BLOCK END - SWITCH on plane state 548 BLANK 549 If this is the player plane who won and is in the end sequence 550 Then set the end graphic indexed by the end game counter 551 Otherwise... 552 Set the plane's graphic to either... 553 NULL if it's dead... 554 Or if it's falling... 555 straight downwards... 556 set to the spinning plane 557 Otherwise just the sideview based on angle 558 BLANK 559 Update the plane's position 560 BLANK 561 If the plane is off the left side of the world... 562 Then keep it pegged to the left wall 563 But... 564 IF the plane is on the edge of the right side of the world... 565 Keep it stuck there 566 BLANK 567 If there is no computer plane currently... 568 And the current plane is flying... 569 or stalled.. 570 or wounded.. 571 or both.. 572 and the game is still on.. 573 Then set the nearest plane to itself 574 BLANK 575 Remove the plane from the object list 576 Put it back on the list 577 BLANK 578 If there is a bomb drop counter... 579 Decrement it 580 IF there is a missile counter... 581 Decrement it 582 If there is a flare counter... 583 Decrement it 584 BLANK 585 If there is no computer plane and the player is at home and alive... 586 Then refuel the plane 587 BLANK 588 If the plane is within the screen... 589 And is falling... 590 or wounded... 591 or wounded and stalled... 592 Create some smoke 593 Set the display segment to video 594 Update the world minimap 595 Return positive value if we're still playing 596 End case for plane being visible 597 BLANK 598 If we've made it this far, then this plane is toast. No need to draw 599 BLOCK END - movepln 600 BLANK 601 BLANK 602 BLANK FIND NEAREST TARGET PLANE 603 Declares and defines nearpln with one argument 604 Argument 1 is an input plane object 605 BLOCK START - nearpln 606 Declares three local object pointers 607 Declare local object indicies, position, ranges, and colors 608 BLANK 609 Point to the input plane 610 Point to the top of the object list 611 BLANK 612 Set the local x to the input plane's x 613 Set the local color to the input plane's color/team 614 BLANK 615 BLOCK START - Loop through all the planes 616 If the plane matches the searcher's color/team... 617 Go to next plane, not a valid target 618 BLANK 619 If the target plane is a computer player.. 620 BLANK 621 And the play mode is not against the computer... 622 and the searching object is not in left hostile territory.. 623 ...or right hostile territory... 624 And there is no candidate plane already set... 625 or if there is... 626 this one is closer... 627 Set the target 628 BLOCK END - Loop through all planes 629 BLOCK END - nearpln 630 BLANK 631 BLANK 632 BLANK 633 BLANK 634 BLANK 635 BLANK REFUEL/RELOAD PLANE 636 Declares and defines refuel with one argument 637 Argument 1 is the plane to refuel 638 BLOCK START - refuel 639 Declares a local object pointer 640 BLANK 641 Point to the input plane 642 Set display segment to main video memory 643 If the plane can update fuel then... 644 Redraw the fuel guage 645 If the plane can update ammo then... 646 Redraw the ammo counter 647 If the plane can update the bombs 648 Redraw the bomb counter 649 If the plane can update the missile capacity... 650 Redraw the missile counter 651 If the plane can update the flare count... 652 Redraw the flare guage 653 BLOCK END - refuel 654 BLANK 655 BLANK 656 BLANK 657 BLANK REARM PLANE COUNTER 658 Declares and defines topup with two arguments 659 Arguments one and two are a counter and a limit variable 660 BLOCK START - topup, provides a counter to rearm a single plane resource 661 Declare a local flag for resource updates 662 BLANK 663 Default flag is flag - no resource update 664 If the resource is already full 665 Then return false, no reloading to do 666 If the max resource is less than 20 (bombs,missiles,flares) 667 Then with every 20 ticks... 668 Increment the resource 669 Set the resource to a positive value (the player flag) 670 End tick check 671 Otherwise, the resource has a lot of units (fuel) 672 Increment the counter in small chunks every tick 673 Set the update flag 674 End check for resource type 675 If any updates pushed us beyond capacity 676 Reset the capacity to max 677 Return true or false if resource was incremented 678 BLOCK END - topup 679 BLANK 680 BLANK 681 BLANK 682 BLANK 683 BLANK MOVE BULLETS 684 Declares and defines move shot with one argument 685 Argument 1 is a pointer to an input object 686 BLOCK START - moveshot, moves bullets through the air 687 Declares a local object pointer 688 Declares local position variables 689 BLANK 690 Point to the input bullet 691 Remove the bullet from the object list while we update 692 If the decremented bullet has no life span left then... 693 Decallocate the object 694 Return its destruction 695 End case for end of life 696 BLANK 697 Update the bullet's position 698 BLANK 699 If the bullet leaves the top of the screen or hits the ground... 700 Or leaves the sides of the world... 701 Deallocate the object 702 Return its destruction again 703 End case for boundary check 704 BLANK 705 Put the bullet back on the object list 706 Update the symbol (white with XOR flag set) 707 Return true - the bullet lives 708 BLOCK END - moveshot 709 BLANK 710 BLANK 711 BLANK MOVE BOMBS 712 Declares and defines movebomb with one argument 713 Argument 1 is a pointer to a bomb object 714 BLOCK START - movebomb, moves an input bomb as it falls 715 Declares a local object pointer 716 Declare local position variables 717 BLANK 718 Point to the input bomb 719 BLANK 720 Remove the bomb from the object list while we update 721 BLANK 722 If the bombs life span has become negative 723 Deallocate the object 724 Set the state to finished 725 Set the display segment to primary video memory 726 Update the world map 727 Return false since the bomb is now gone 728 End case for end of life bomb 729 BLANK 730 Update the fall angle of the bomb 731 BLANK 732 If the bomb hasn't started falling yet 733 Start the bomb sound effect 734 BLANK 735 Update the bomb's position 736 BLANK 737 If the bomb has left the world (not the top though) 738 Decallocate the object from memory 739 Stop the sound playing 740 Set the state to finished 741 Set the current display segment to primary video 742 Update the world map 743 Return false for the bombs destruction 744 End case for bomb leaving the world 745 BLANK 746 Update the graphic to the current orientation, maybe have changed 747 Put the bomb back on the object list 748 BLANK 749 If the bomb has left the top of the screen... 750 Return false for now(nothing to display) 751 BLANK 752 Set the current display to the primary video segment 753 Update the world drawing 754 Return true to display the bomb 755 BLOCK END - movebomb 756 BLANK 757 BLANK 758 BLANK UPDATE FALLING DIRECTION (BOMBS, SHRAPNEL) 759 Declares and defines adjustfall with one argument 760 Argument 1 is a pointer to a bomb 761 BLOCK START - adjustfall, changes bomb falling angle 762 Declares a local object pointer 763 BLANK 764 Point to the input bomb object 765 If the decremented bomb's life is zero 766 And it is falling... 767 And moving left... 768 Then slow it's left progress 769 Otherwise it might be moving right... 770 If there is right progress.. 771 Slow the right progress 772 If the problem is not falling 10 pixels per second 773 Increase its fall speed 774 Reset the bomb life counter 775 End case for changing bomb fall 776 BLOCK END - adjustfall 777 BLANK 778 BLANK 779 BLANK UPDATE OBJECT FALLING ANGLES 780 Declares a defines symangle with one argument 781 Argument 1 is an input object 782 BLOCK START - symangle, coverts movement vectors to one of eight angles 783 Declare local variables for movement speeds 784 BLANK 785 Get the speed along the x vector 786 Get the speed alogn the y vector 787 If the bomg isn't moving fowward... 788 And it is falling... 789 Then the bomb should face angle 6 (straight down) 790 Otherwise, it's not moving forward/backward but.. 791 If it's going up... 792 Choose return angle 2 (straight up) 793 Otherwise, a completely motionless bomb... 794 So return angle 6 (straight down) 795 However, if the bomb does have forward movement... 796 To the right... 797 And it's falling.. 798 Make it angle 7 - down and to the right 799 But if it's going right.. 800 And upwards... 801 Then it's going up and to the right 802 Finally.. 803 If it's just going to the right, then face that way 804 The final case is moving left... 805 and downward... 806 Return angle 5 for left and down.. 807 Otherwise... 808 it's moving upwards 809 So return angle 3 for up and left 810 If this stuff fails... 811 Then it must be angle 4, down and left... Q.E.D. 812 BLOCK END - symangle 813 BLANK 814 BLANK 815 BLANK MOVE MISSILES 816 Declares and defines movemiss with one argument 817 Argument 1 is a pointer to a missil object 818 BLOCK START - movemiss 819 Declares a local object pointer 820 Declare temporary variables for 821 Declares another local object pointer for the target 822 BLANK 823 Point to the input missile 824 BLANK 825 Remove the missile from the object list while we update it 826 BLANK 827 If the missile has reached the end of its life 828 Return the object from the memory pool 829 Set its state to finished 830 Set the display segment to the video memory 831 Update the world minimap 832 Return false since there is no display 833 End case for end of missile life 834 BLANK 835 If the missile is flying... 836 And the target is not the object owner... 837 And its on an odd tick.. 838 And there is a valid target 839 Reaffirm the object target 840 Adjust the aim of the missile 841 Save the new angle... 842 ..with the updated flap position accounting for angle wrap 843 Update the missile's movement vectors in the x... 844 and y vector.. 845 End case for odd tick, for all ticks... 846 Update the missile position 847 If the decemented life counter runs out, or the missile is too high... 848 Change the missile state to falling.. 849 And give it some extra life 850 End of case for missile flying 851 Otherwise the missile is no longer flying 852 Adjust its fall angle.. 853 Account for angle wrap 854 Update the missile's position 855 End case for missile movement 856 BLANK 857 If the missile has left the world... 858 Decallocate the object 859 Set its state to finished 860 Update the screen segment to the video ram 861 Update the world minimap 862 Return false since there's no display 863 End case for leaving the world 864 BLANK 865 Update the missile graphic every tick based on angle 866 Readd the object to the list 867 BLANK 868 If the missile has left the top of the screen 869 Return false, nothing to draw 870 BLANK 871 Update the screen segment to the video ram 872 Update the world minimap 873 Return true to draw the missile 874 BLOCK END - movemiss 875 BLANK 876 BLANK 877 BLANK MOVE FLARES 878 Declares and defines moveburst with one argument 879 Argument 1 is a pointer to a flare 880 BLOCK START - moveburst, moves a flare (falls to the ground) 881 Declares a local object pointer 882 Declare local position variables 883 BLANK 884 Point to the input flare object 885 Remove it from the object list 886 If the flare has reached the end of its life span 887 Remove the owner flag 888 Return the object to the memory pool 889 Return false - nothing to display 890 End case for flare end of life 891 BLANK 892 Adjust the flare's fall direction 893 Update the flare's position and return the new position 894 BLANK 895 IF the flare hits the ground or leaves the edges of the world... 896 Remove the flare owner 897 Remove the flare from it's sad existence 898 Return false 899 End case for leaving the world 900 BLANK 901 Reset the object target 902 Update the flare graphic 903 Readd it to the list 904 Display the flare if it's still on the screen 905 BLOCK END - moveburst 906 BLANK 907 BLANK 908 BLANK 909 BLANK MOVE TARGETS 910 Declare and define movetarg with one argument 911 Argument 1 is a pointer to a target object 912 BLOCK START - movetarg, moves a target (fires at player after game 1) 913 Declare a local range integer 914 Declares two local object pointers 915 BLANK 916 Point to the target 917 Point to the top of the object list (usually the player) 918 Reset the target's firing state 919 If this isn't the first game (difficulty) and the building isn't dead.. 920 And the target plane is flying... 921 or stalled.. 922 or wounded.. 923 or wounded and stalled.. 924 and is on the opposite team... 925 ...and the delay counter matches... 926 ...and is within positive x range... 927 ...and positive y range... 928 ...and isn't too far away... 929 Then take the shot already!! 930 BLANK 931 If the target building's hit counter is below zero.. 932 Reset the hit counter 933 BLANK 934 Update the graphic based on if the building is still alive... 935 If so, use the orientation symbol 936 Otherwise, use the broken building symbol 937 Return true, buildings never vanish, dead or alive 938 BLOCK END - movetarg 939 BLANK 940 BLANK 941 BLANK MOVE SHRAPNEL 942 Declares and defines moveexpl with one argument 943 Argument 1 is a pointer to a piece of an explosion 944 BLOCK START - moveexpl, moves shrapel after an explosion 945 Declares a local object pointer 946 Declare local position variables 947 Declare a local orientation variable 948 BLANK 949 Point to the input piece of shrapnel 950 Save the object's orientation 951 Remove the shrapnel from the list for processing 952 BLOCK START - shrapnel is dead, if the life counter has gone negative.. 953 ..and the object has a graphic.. 954 Stop playing its sound 955 Deallocate the object 956 Return its destruction to the caller 957 BLOCK END - shrapnel is dead 958 BLANK 959 BLOCK START - shrapnel is at zero life, If object decrements to 0 960 If the object is falling... 961 and it is moving less.. 962 then slow it's leftward movement 963 Otherwise... 964 Check if it's moving right.. 965 And if so, slow it's rightward movement. 966 If the shrapnel isn't in fast freefall 967 ...or doesn't have a graphic while not moving 968 Make it fall faster 969 Reset the object life counter 970 BLOCK END - shrapnel is at zero life 971 BLANK 972 Update the object's position and store in our local variables 973 BLANK 974 If the shrapnel has fallen in to the ground... 975 ..or off either end of the world.. 976 Then if it has a valid graphic.. 977 Stop playing it's sound 978 and remove it from memory 979 Return the vanishing shrapnel 980 End case for dead shrapnel check 981 Increment the shrapnel's hit counter 982 BLANK 983 Ad it back to the object list 984 Update the graphic, if needed 985 Return true if the object is below the top of the screen 986 BLOCK END - moveexpl 987 BLANK 988 BLANK 989 BLANK MOVE SMOKE 990 Declares and defines movesmok with one argument 991 Argument 1 is a pointer to an input smoke object 992 BLOCK START - movesmok, moves a smoke object (actually just decays it) 993 Declares a local object pointer 994 Declare a local variable to hold state 995 BLANK 996 Point to the smoke object 997 Decrement the smoke life, and if it's 0.. 998 Grab the owner's state and if it isn't falling... 999 Or wounded.. 1000 Or really rounded.. 1001 Or dead... 1002 Then the plane is ok so decallocate the smoke 1003 and return its demise 1004 End case for zero life 1005 Reset the smoke graphic to XOR owner color 1006 BLANK 1007 Return that the smoke lives 1008 BLOCK START - movesmok 1009 BLANK 1010 BLANK 1011 BLANK MOVE FLOCK OF BIRDS 1012 Declares and defines moveflck with one argument 1013 Argument 1 is a pointer to a flock of birds 1014 BLOCK START - moveflck 1015 Declares a local object pointer 1016 Declares local position integers 1017 BLANK 1018 Point to the input bird flock 1019 Remove the flock from the object list while we work on it 1020 BLANK 1021 If the bird flock's life has dropped to -1.. 1022 Then swap to primary video display 1023 Update the world object display 1024 Deallocate the bird object 1025 Return false, no longer exists 1026 End change for dead bird flock 1027 BLANK 1028 Decrement flock life counter and if it's now zero... 1029 Change the bird flap graphic 1030 Reset the bird flock life to 5 ticks 1031 End case for graphic change 1032 BLANK 1033 If the flock has flown beyond it's cage at work positions 50 and 2950.. 1034 Reverse the flock's travel direction 1035 BLANK 1036 Update the flock's position storing the new position in local variables 1037 Put the flock back in to the object list 1038 Update the flock graphic 1039 Reset to main video display 1040 Update the world minimap 1041 Return true, the flock lives on 1042 BLOCK END - moveflck 1043 BLANK 1044 BLANK 1045 BLANK MOVE BIRDS 1046 Declares and defines movebird with 1 argument 1047 Argument 1 is a pointer to a single bird 1048 BLOCK START - movebird, moves a single bird 1049 Declares a local object pointer 1050 Declare local position integers 1051 BLANK 1052 Point to the bird 1053 BLANK 1054 Remove the bird from the object list while we process it 1055 BLANK 1056 If the bird's life counter falls negative... 1057 Deallocate the object slot 1058 Return false 1059 End of case for -1 life counter 1060 If the bird's life falls to -2 then... 1061 Change vertical direction 1062 Mask x movement to fall between 0 and 7 minus 4 1063 Reset the bird life counter to 4 1064 End case for -2 bird life counter 1065 Otherwise, decrement bird life and if the counter is at 0 1066 Change orientation (wing flap) 1067 Reset bird life to 4 1068 End change for bird lifecycle 1069 BLANK 1070 Update the bird location based on movement, store position in x and y 1071 BLANK 1072 Add the bird object back to the object list 1073 Update the bird graphic, the wing flag state may have changed 1074 If the bird flies too high, hits the ground... 1075 or flies off the left or right of the world... 1076 Then invert the bird's vertical direction 1077 Set it's life to -2 1078 Return faulse 1079 End case for world boundary check 1080 If we've made it this far, return true 1081 BLOCK END - movebird 1082 BLANK 1083 BLANK 1084 BLANK 1085 BLANK MOVE OX (NOT LITERALLY, MOVE FROM ALIVE TO DEAD) 1086 Declares and defines moveox with one argument 1087 Argument 1 is a pointer to an ox 1088 BLOCK START - moveox, mooooooves the ox (not really used) 1089 BLANK 1090 Sets the ox graphic to dead 1091 Returns true always 1092 BLOCK END - moveox 1093 BLANK 1094 BLANK 1095 BLANK 1096 BLANK HANDLE PLANE CRASH 1097 Declare and define crashpln with one argumen 1098 Argument 1 is a pointer to the crashing plane 1099 BLOCK START - crashpln, handles crashes with other planes 1100 Declares a local object pointer 1101 BLANK 1102 Point to the input plane object 1103 BLANK 1104 If the object is moving left... 1105 Tip the plane 32 degrees counter clockwise 1106 Otherwise, it's moving right so... 1107 Tip the plane 32 degrees clockwise 1108 BLANK 1109 Set the object's state to crashed with variations for ghosts or not 1110 A crashed plane isn't at home 1111 Set all motion to 0 1112 BLANK 1113 Point to the other plane 1114 Set the hit counter based on if the nearest opponent's x difference.. 1115 ...and the nearest opponents y difference... 1116 If to close then hit count is 64 ticks, otherwise it's safe so 32 ticks 1117 BLANK 1118 BLOCK END - crashpln 1119 BLANK 1120 BLANK 1121 BLANK HIT ANOTHER PLANE 1122 Declare and define hitpln with 1 argument 1123 Argument 1 is a pointer to the hit plane 1124 BLOCK START - hitpln, sets state for a plane that was hit 1125 Declare a local pointer to an object 1126 BLANK 1127 Point to the input plane 1128 Reset the last movement variables 1129 Set the plane's hit counter to the falling default (10) 1130 Set the plane to falling 1131 The plane can't be at home if it's falling 1132 BLOCK END - hitpln 1133 BLANK 1134 BLANK 1135 BLANK PLANE STALL 1136 Declare and define stallpln with 1 Argument 1137 Argument 1 is a pointer to a plane object 1138 BLOCK START - stallpln, sets a plane to stall mode 1139 Declares a local object pointer 1140 BLANK 1141 Point to the input plane 1142 Reset all of the movement vectors and orientations 1143 Set the plane's angle to 14 (down and to the right) 1144 Set the plane's speed to 0 1145 Set the plane's vertical motion to 0 1146 Set the hitcounter to stall (delay's player actions) 1147 Set plane's state to stall with variations on current ghost state... 1148 ...or based on current wounded state 1149 The plane can't be at base if it's stalled 1150 BLOCK END - stallpln 1151 BLANK 1152 BLANK 1153 BLANK 1154 BLANK INSERT OBJECT IN TO LINKED LIST 1155 Declare and define insertx with 2 arguments 1156 Arguments 1 and 2 are pointers to objects 1157 BLOCK START - insertx, inserts object in to object linked list 1158 Declare a local pointer to an object 1159 Declares a local variable used for object x coordinate 1160 BLANK 1161 Point to the 2nd input object 1162 Store the 1st object's x coordinate 1163 If the first object is less than the second object... 1164 Loop while the first object continues to be left of the target 1165 Follow the linked list backward 1166 Recheck loop invarient and repeat 1167 Otherwise, we're to the right of the object so... 1168 Loop while the input object's x is greater than the target 1169 Follow the list until the invarient breaks 1170 Set the previous object 1171 End list traversal 1172 Set the input object's next to the target object's next 1173 Set the input object previous to the target 1174 Fix up the previous object 1175 Fix up the next object 1176 BLOCK END - insertx 1177 BLANK 1178 BLANK 1179 BLANK 1180 BLANK DELETE OBJECT FROM LINKED LIST 1181 Declare and define deletex with one argument 1182 Argument 1 is a pointer to a game object 1183 BLOCK START - deletex, deletes an object from the linked list 1184 Declares a local object pointer 1185 BLANK 1186 Point to the input object 1187 Change the next object's parent to the previous (no check for NULL?) 1188 Change the previous object's child to the next object 1189 BLOCK END - deletex 1190 EOF�