How to Make a Basic Platformer
|Описание||Как создать платформер|
|Область знаний||Информатика, Game design, Геометрия|
|Область использования (ISTE)||Computational Thinker|
|Близкие рецепту понятия||Mario Bros|
|Среды и средства для приготовления рецепта:||Scratch|
A platformer is a simulation of actual physics that take place in real life. Objects fall, move, slide, jump, and bounce, and a platformer associates those properties into a game in which one controls a character and tries to move it toward a goal. This tutorial will explain how to make a basic platformer.
Creating the Platformer Sprite
The platformer sprite is the avatar controlled by the player. Its appearance can affect gameplay slightly, depending on the angles and size of its Costumes. For example, a character shouldn't be saved from a fall because the brim of her hat snagged on the edge of a cliff. Sprites that are animated by lots of costume changes are even more tricky, as a changing costume might get pulled inside the ground and get stuck.
Below is an example of a simple script for a platformer sprite. It uses two variables:
- "X velocity" stores a value representing the sprite's horizontal speed. It was set as a local variable by checking the option "For this sprite only" in the creation dialog. This means (i) the variable can only be changed by scripts in the same sprite, (ii) the variable name does not needlessly clutter the variable pane of other sprites, and (iii) the same variable name may be used in other sprites without causing conflicts.
- "Gravity" stores a value reflecting the strength of the sprite's tendency to fall. In this example it is set as a negative number because moving a sprite downwards requires making the value of its Y position smaller. "Gravity" need not be set as a local variable; a realistic game would subject all its characters to the same gravitational force.<ref>wikipedia:Galileo's Leaning Tower of Pisa experiment</ref>
when green flag clicked set [gravity v] to [-5] forever if <key (left arrow v) pressed?> then // using "else" saves processing later ifs unnecessary set [x velocity v] to [-4] else if <key (right arrow v) pressed?> then set [x velocity v] to  else set [x velocity v] to  // no arrow keys means no movement end end if <not <touching (ground sprite v)?>> then // sprite falls till touching ground change y by (gravity) end change x by (x velocity) end
Here is the code for platformer walking.
when green flag clicked forever if <key (a v) pressed?> then change [velocity v] by (-1) end if <key (d v) pressed?> then change [velocity v] by (1) end speed cap (5)::custom change x by (velocity)
define speed cap (max speed) if <(velocity) > (max speed)> then set [velocity v] to (max speed) end if <(velocity) < ((max speed) * (-1))> then set [velocity v] to ((max speed) * (-1)) end set [velocity v] to ((velocity)*(0.9))
To jump, use this code:
when green flag clicked forever if <key (up arrow v) pressed?> then // the jumping key repeat  change y by  end repeat until <touching (ground sprite v)> change y by [-5] end end end
Colors can be used in a platform for detection of the end of a level or an object which sends one back to the beginning of the level. For this tutorial, assume the following:
- The character sprite performing the physics is named "Player"
- Black is the color of the platform, or ground and walls, in which the character cannot pass through
- Red is the color that sends one back to the beginning of the level they are on
- Yellow is the color which must be reached to move on to the next level
- Backgrounds are used as levels instead of sprites
- Scrolling is not incorporated
The shapes do not need to be geometric, but can be organic, meaning an unordinary, inconsistent structure. There can be curvature to the various colors and platforms, which can be used to create diverse, numerous levels. The following image displays an example of some organic shapes being used:
When the levels are finished, add the following script to the "Player" sprite:
when gf clicked forever if <touching color [#FF0000]?> then//if in contact with the color red go to x:(-180) y:(-47) // relocate to the start end if <touching color [#FFFF00]?> then//if at the end of a level go to x:(-180) y:(-47) // relocate to the start switch backdrop to (next backdrop v)// next level end
The scripts within the "forever" loop can be merged with the larger physics script shown farther above. Merging the scripts reduces the amount of conditions being checked at once and can possibly make the project more uniform and orderly, meaning the "Player" makes each movement and then checks for the conditions instead of the conditions possibly being checked during the sprite's movement.
- A condition is a statement that is checked for a true/false response. In the example above, when the sprite checks if it's touching a color, it's checking a condition.
Then add the following script to any sprite:
when gf clicked switch backdrop to (level 1 v)//begin with the first level
Lastly, add the following script to the "Player" sprite:
when gf clicked show wait until <([backdrop # v] of [Stage v]) = (amount of backdrops)>//wait until the last level is reached stop [all v]
Making the Win Background
Last of all, comes the win background. After finishing all the levels in the platformer, something would come up that says something like "You Win!". Put it as the last costume in the sprite/background. It can be some text in a basic white background saying "You win" or the art can be complex.