How do sprites jump and what logic is it based upon in c++?

Question

Hey guys I'm stuck trying to implement a jump when the up key is pressed with c++ in Visual Studio.I would like momentum as in while in air you can still use the right and left keys to move eg Super mario :D

This is Basically What I Have for my Main Class

(MyProjectMain):

void MyProjectMain::KeyDown(int iKeyCode)
{
    switch ( iKeyCode )
    {
    case SDLK_ESCAPE: // End program when escape is pressed
        SetExitWithCode( 0 );
        break;
    case SDLK_SPACE: // SPACE Pauses
        break;
    case SDLK_UP:
        Player::JumpPlayer();
        break;
    }
}

(Player class):

void Player::DoUpdate(int iCurrentTime)
{
        /*
        // Change speed if player presses a key 
        if ( GetEngine()->IsKeyPressed( SDLK_UP ) )
        m_iCurrentScreenY -= 5; 
        if ( GetEngine()->IsKeyPressed( SDLK_DOWN ) ) 
        m_iCurrentScreenY += 5;
        */
        if ( GetEngine()->IsKeyPressed( SDLK_LEFT ) ) 
        m_iCurrentScreenX -= 3; 
        if ( GetEngine()->IsKeyPressed( SDLK_RIGHT ) ) 
        m_iCurrentScreenX += 3; 
        if ( m_iCurrentScreenX < 0 ) 
        m_iCurrentScreenX = 0; 
        if ( m_iCurrentScreenX >= GetEngine()->GetScreenWidth() - m_iDrawWidth ) 
        m_iCurrentScreenX = GetEngine()->GetScreenWidth() - m_iDrawWidth; 
        if ( m_iCurrentScreenY < 0 ) 
        m_iCurrentScreenY = 0; 
        if ( m_iCurrentScreenY >= GetEngine()->GetScreenHeight() - m_iDrawHeight) 
        m_iCurrentScreenY = GetEngine()->GetScreenHeight() - m_iDrawHeight; 

        // Ensure that the object gets redrawn on the display, if something changed 


        RedrawObjects(); 
}


void Player::JumpPlayer(void)
{   

}

I must Mention That I have successfully made the sprite move left and right its just this jump that has been taking me so long. I would love if you can include your solution in the jump Function

Thanks A whole Lot !!!

`m_iCurrentScreenY -= 3;` assuming the coordinate system has its origin at top-left corner (That is if you want to jump straight up) — avmohan, Mar 22 '14 at 06:26
@v3ga Thats just going to shift the sprite to the top and nothing will happen after that. I am looking for a simple jump like in mario like when you press space bar, it jumps up and then comes back to the floor Thanks — ipalibowhyte, Mar 22 '14 at 06:41
Some hints to find here: http://answers.unity3d.com/questions/151191/problem-with-jumping-and-frames-per-second.html — deviantfan, Mar 22 '14 at 07:01
And some more here: http://stackoverflow.com/questions/13023652/game-jump-logic — Jongware, Mar 22 '14 at 11:26

score 1 · Answer 1 · edited Jun 20 '20 at 09:12

Not sure what game engine or physics engine you're using, and if you're wanting to create your own, then you can ignore this answer :)

Anyways, no sense in reinventing the wheel. Cocos2D is an open source C++ game engine with Box2D physics engine support. I'd highly recommend checking it out.

Then, it becomes as simple as creating a CCSprite to represent your "mario" dude ;) and add a CCJumpBy action to him to simulate a parabolic jump movement.

If you want him to move left and right while in the air, check out this guy's post here

Good luck!

How do sprites jump and what logic is it based upon in c++?

1 Answers1