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How To Move Sprite With Keyboard Input

This article will show you how to move a sprite with the help of keyboard inputs.

Level

Advanced

Details

You can set any direction for any key and the sprite will move according to the command it gets. In this program a sprite can only go left, right, up or down.

To be able to do that, you need to do follow these steps:

  1. Load an image and create a sprite from it
  2. Set an initial position (Sprite Set X, Sprite Set Y) for that sprite
  3. Then clear the screen (Clear Screen) with Color White
  4. Now depending on the user's command-
  • Set x velocity (Sprite Set X) of the sprite any positive value but keep the y velocity (Sprite Set Y) as 0 if it gets the command to go right (Key Down(VK_RIGHT))
  • Else set x velocity (Sprite Set X) of the sprite any negative value but keep the y velocity (Sprite Set Y) as 0 if it gets the command to go left (Key Down(VK_LEFT))
  • Else set y velocity (Sprite Set Y) of the sprite any negative value but keep the x velocity (Sprite Set X) as 0 if it gets the command to go up (Key Down(VK_UP))
  • Else set y velocity (Sprite Set Y) of the sprite any positive value but keep the x velocity (Sprite Set X) as 0 if it gets the command to go down (Key Down(VK_DOWN))
  • Else in all other cases set the X and Y value for the sprite's velocity (Sprite Set Dx and Sprite Set Dy) as 0

     5.  Then draw (Draw Sprite) and update (Update Sprite) the sprite to show it on the screen.

The code below shows all the concepts implemented as a program.

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  • program HowToMoveSpriteWithKeyboardInput;
uses SwinGame,sgTypes;

procedure Main();
var
    ball : Sprite;
begin
    OpenGraphicsWindow('Move a Sprite with Keyboard Input' ,800 ,600 );
    LoadBitmapNamed('ball' ,'ball_small.png' );
    ball := CreateSprite(BitmapNamed('ball' )  );
    SpriteSetX(ball ,385 );
    SpriteSetY(ball ,285 );
    repeat
        ProcessEvents();
        ClearScreen(ColorWhite );
        if  KeyDown(vk_RIGHT )    then
        begin
            SpriteSetDx(ball ,1 );
            SpriteSetDy(ball ,0 );
        end 
        else
            if  KeyDown(vk_LEFT )    then
            begin
                SpriteSetDx(ball ,-1 );
                SpriteSetDy(ball ,0 );
            end 
            else
                if  KeyDown(vk_UP )    then
                begin
                    SpriteSetDx(ball ,0 );
                    SpriteSetDy(ball ,-1 );
                end 
                else
                    if  KeyDown(vk_DOWN )    then
                    begin
                        SpriteSetDx(ball ,0 );
                        SpriteSetDy(ball ,1 );
                    end 
                    else
                    begin
                        SpriteSetDx(ball ,0 );
                        SpriteSetDy(ball ,0 );
                    end;
        DrawSprite(ball );
        UpdateSprite(ball );
        RefreshScreen();
    
    until WindowCloseRequested();
    FreeSprite(ball );
    ReleaseAllResources();
end;
begin
    Main();
end.
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  • #include 
#include "SwinGame.h"
int main() 
{
    sprite  ball;
    open_graphics_window("Move a Sprite with Keyboard Input" ,800 ,600 );
    load_bitmap_named("ball" ,"ball_small.png" );
    ball = create_sprite(bitmap_named("ball" ) ) ;
    sprite_set_x(ball ,385 );
    sprite_set_y(ball ,285 );
    do 
    {
        process_events();
        clear_screen(color_white );
        if ( key_down(VK_RIGHT )  )
        {
            sprite_set_dx(ball ,1 );
            sprite_set_dy(ball ,0 );
        }
        else
            if ( key_down(VK_LEFT )  )
            {
                sprite_set_dx(ball ,-1 );
                sprite_set_dy(ball ,0 );
            }
            else
                if ( key_down(VK_UP )  )
                {
                    sprite_set_dx(ball ,0 );
                    sprite_set_dy(ball ,-1 );
                }
                else
                    if ( key_down(VK_DOWN )  )
                    {
                        sprite_set_dx(ball ,0 );
                        sprite_set_dy(ball ,1 );
                    }
                    else
                    {
                        sprite_set_dx(ball ,0 );
                        sprite_set_dy(ball ,0 );
                    }
        draw_sprite(ball );
        update_sprite(ball );
        refresh_screen();
    }
    while ( ! (window_close_requested() ) );
    free_sprite(ball );
    release_all_resources();
    return 0;
}
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