Adding initial horizontal motion into a jumping procedure

[Mayb123]

i am trying to allow for horizontal running velocity to be incorporated into the jump procedure giving a trajectory with a slight 2-3 pixel restraint on how much you can affect the trajectory by holding down the a or d keys (wasd controls). for example's sake, i took out the variables that require external files and replaced the character with a dot. any help would be greatly appreciated. thanks

code:

setscreen ("offscreenonly") setscreen ("nobuttonbar") setscreen ("graphics:640;480") var key : array char of boolean var chief : array 1 .. 5 of int var ground, vcap, x, y, vx, vy, ax, g, charx, chary, carvx : real const gravity := 0.06 const decel := 0.95 const mcrad := 5 var platformx1 : array 1 .. 6 of int := init (50, 100, 150, 200, 250, 300) var platformx2 : array 1 .. 6 of int := init (60, 110, 160, 210, 260, 310) var platformy1 : array 1 .. 6 of int := init (50, 100, 150, 200, 250, 300) var platformy2 : array 1 .. 6 of int := init (60, 110, 160, 210, 260, 310) var pos : int := 3 % chief (1) := Pic.FileNew ("MC sprite lsiderun.bmp") % chief (2) := Pic.FileNew ("MC sprite lside.bmp") % chief (3) := Pic.FileNew ("MC sprite.bmp") % chief (4) := Pic.FileNew ("MC sprite rside.bmp") % chief (5) := Pic.FileNew ("MC sprite rsiderun.bmp") x := 10 y := 10 vx := 0 ax := .5 vy := 0 % PROCEDURES procedure samplelevel     for i : 1 .. 6         drawfillbox (platformx1 (i), platformy1 (i), platformx2 (i), platformy2 (i), black)     end for end samplelevel procedure movement     if key ('d') and vx <= 5 and y = 10 then         vx += 0.059         pos := 4     elsif key ('a') and vx >= -5 and y = 10 then         vx -= 0.059         pos := 2     else         vx *= decel     end if end movement procedure velocity     x += vx     y += vy end velocity procedure jump %fix this part by adding horizontal motion     if y > mcrad then         vy -= gravity     else         vy := 0     end if     if vy = 0 and key ('w') then         vy := 2     end if     % if key ('w') then     %     vy += ax     %     % % end if     % % if round (y) > 10 then     % %     ax += gravity %Fix these     % % end if     % if round (y) <= 0 then     %     vy := 0     % end if end jump % procedure right %     if key (KEY_RIGHT_ARROW) and vx <= 5 and y = 10 then %         vx += 0.099 %         pos := 4 %     else %         vx *= decel %     end if % end right % procedure left %     if key (KEY_LEFT_ARROW) and vx >= -5 and y = 10 then %         vx -= 0.099 %         pos := 2 %     else %         vx *= decel %     end if % end left procedure background     drawfillbox (0, 0, maxx, maxy, black)     drawfillbox (10, 10, 630, 470, white) end background procedure endofscreendetection     if round (x) >= 633 and round (x) <= 640 then         x := 8     end if     if round (x) <= 7 and round (x) >= 0 then         x := 632     end if end endofscreendetection %IMPLEMENTATION loop     Input.KeyDown (key)     cls     movement     endofscreendetection     jump %comment this to allow horizontal motion using a and d keys     velocity     drawfilloval (round (x), round (y), 2, 2, black)     % Pic.Draw (chief (pos), round (x), round (y), picMerge)     delay (10)     View.Update end loop

[richcash]

Well, it really depends on you game. Do you want it to be realistic, do you want it to be like mario, etc.

Generally, the faster someone is moving before jumping the further horizontally they will go. This suggests you should divide the x velocity on ground right before the jump by some constant and use the quotient as the new x velocity in air. The velocity of the object in the air is not affected by ground friction, so you should disable that while in mid-flight. You may choose to add air resistance, but it will be VERY small so you can also ignore it.


The rest is up to you and your game. When the character lands you probably want to set all velocities to 0 (unless the character is on skates, where he would keep going on ground).

You may want the user to be able to affect the 'take-off'. To do this check if the user is pressing the appropriate direction at the 'instant' the jump key is pressed. If they are, then you add more to the x velocity in that direction. If they aren't (they let go and then press jump key, you may infer that they want to jump straight up, but will likely still have some x velocity). You may also want to make a forward jump not have as much y velocity as a straight-up jump, because the person is splitting their jump force to go both forward and up.

In mario-like games the user can effect the velocity of the character while in mid-air. I don't think someone can do this in real life, but it still might be good for your game.

There are a number of other things that you can put in as well (that make it more fun or more realistic).