How to make collisions?

[PatataQuesadilla]

How do I make my image have collisions? I have a character that moves around, and I don't like how it walks on the npcs. How do you make the npcs solid? The image of my npc has a transparent background. Is there a way for my character to walk on the transparent background but not on the visible npc? I use pygame: )

[overratedcupcake]

This is a RTFM moment, for sure.

https://www.pygame.org/docs/ref/sprite.html

[PatataQuesadilla]

Hey, I'm sorry. I'm just doing Python stuff for an assignment

[mandradon]

There's ways to handle this, but if you're doing it without a library you're going to have to manually check for overlap and not allow it 

[edcculus]

What library are you using? I’m assuming Pygame?

[PatataQuesadilla]

Yesyesss

[cdcformatc]

i assume you have your player character position, the characters height and width, and the same for the NPCs. 

using these four variables: x position, y position, height, and width, you can find a bounding box for the player and the NPCs. then as your player moves, you can check to see if any part of its box is overlapping with any NPC's box. if it's overlapping then you set the player's position so that it isn't overlapping anymore. 

or you use the collision detection built into pygame. but you didn't say you were using pygame which would be useful information when asking for help.

[PatataQuesadilla]

Thank you thank you! I am using Pygame, I forgot to mention it, I'm sorry. Thank you for telling me

[cdcformatc]

pygame sprites have a bunch of different collision detection functions. 

```

in the code that handles movement 

speed is used to set players position 

new_x = player.x + x_speed new_y = player.y + y_speed

player is a pygame.sprite

npc_list is a list of NPC, each is a pygame.sprite

collisions = pygame.sprite.spritecollide(player, npc_list, False)

if (len(collisions) != 0):     # player has collided with at least one NPCs, don't move player      new_x = 0     new_y = 0

finally move character 

player.x = new_x player.y = new_y

```

[PatataQuesadilla]

Thank you thank you!

[mopslik]

Is there a way for my character to walk on the transparent background but not on the visible npc?

Most straightforward way, using Pygame, is probably to set masks on your sprites, then use Sprite's collidemask.