I have spent the past 3 days trying to understand this but with every article I have read and every youtube video I have watched I have failed to comprehend the concept. I have given this my best go at listening and reading from what I have seen online, before asking here.
I just want one rectangle to go up one slope. I am not after a function for this. Each tutorial/article/video I watch explains how their function/class works. Some are using lists of classes and functions that call other functions inside them. It gets very abstract and it is to much for me right now.
I need someone to really baby this down for me it seems. No functions and no classes. I just want to move one rectangle up one 45 degree slope.
One youtube video explained that I need y = mx + b. But did not explain how to use this function. So if anyone out there has a formula for a basic 45 degree slope and can show me in my own code how to use it without functions or classes, i will be grateful.
After I understand it I can make my own functions and classes for implementing it. My attempt at this has been to make a rectangle behind my ramp image. Is this wrong? Should I be using a single line?
My attempt at code:
import pygame
import sys
pygame.init()
clock = pygame.time.Clock()
screensize = (800, 600)
screen = pygame.display.set_mode(screensize)
colour = [(0, 0, 0), (255, 0, 0), (255, 255, 255), (114, 216, 242), (200, 200, 200), (255, 199, 241), (50, 50, 50)]
# black 0 #red 1 #white 2 #light_blue 3 #gray 4 #light_pink 5 #dark_gray 6
moving_up = False
moving_down = False
moving_left = False
moving_right = False
gravity = 5
def collide(rect, rectangle_list):
hit_list = []
for rectangle in rectangle_list:
if rect.colliderect(rectangle):
hit_list.append(rectangle)
return hit_list
def move(rect, movement, tiles):
collision_types = {'top': False, 'bottom': False, 'right': False, 'left': False}
rect.x += movement[0]
hit_list = collide(rect, tiles)
for tile in hit_list:
if movement[0] > 0:
rect.right = tile.left
collision_types['right'] = True
elif movement[0] < 0:
rect.left = tile.right
collision_types['left'] = True
rect.y += movement[1]
hit_list = collide(rect, tiles)
for tile in hit_list:
if movement[1] > 0:
rect.bottom = tile.top
collision_types['bottom'] = True
elif movement[1] < 0:
rect.top = tile.bottom
collision_types['top'] = True
return rect, collision_types
player_rect = pygame.Rect(100, 51, 50, 50)
while True:
screen.fill(colour[6])
pygame.draw.polygon(screen, (255, 0, 255), [(300, 500), (300, 550), (250, 550)])
# ~~~~~~ List of rectangles
rectlist = []
small_rect = pygame.Rect(200, 200, 50, 50)
bottomrect_1 = pygame.Rect(0, screensize[1] - 50, screensize[0], 50)
bottomrect_2 = pygame.Rect(300, screensize[1] - 100, screensize[0], 50)
D_rect = pygame.Rect(250, screensize[1] - 100, 50, 50)
rectlist.append(small_rect)
rectlist.append(bottomrect_1)
rectlist.append(bottomrect_2)
# ~~~~~~ Player Movement
player_movement = [0, 0]
if moving_up:
player_movement[1] -= 2
if moving_down:
player_movement[1] += 2
if moving_left:
player_movement[0] -= 2
if moving_right:
player_movement[0] += 2
player_movement[1] += gravity
# ~~~~~~ Player Collision
my_rect, collision = move(player_rect, player_movement, rectlist)
# my attempt at this diagonal humbug. D_rect is the diagonal rect. (the slope)
if my_rect.colliderect(D_rect):
yy = D_rect.height + (my_rect.x - D_rect.x) * 1
my_rect.y -= yy/3.6
# ~~~~~~ Event Loop
for event in pygame.event.get():
if event.type == pygame.QUIT:
pygame.quit()
sys.exit()
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_ESCAPE:
pygame.quit()
sys.exit()
if event.key == pygame.K_w:
moving_up = True
if event.key == pygame.K_s:
moving_down = True
if event.key == pygame.K_a:
moving_left = True
if event.key == pygame.K_d:
moving_right = True
if event.key == pygame.K_SPACE:
gravity = -gravity
if event.type == pygame.KEYUP:
if event.key == pygame.K_w:
moving_up = False
if event.key == pygame.K_s:
moving_down = False
if event.key == pygame.K_a:
moving_left = False
if event.key == pygame.K_d:
moving_right = False
# ~~~~~~ Draw.
pygame.draw.rect(screen, (0, 255, 125), D_rect, 1)
pygame.draw.rect(screen, colour[3], small_rect)
pygame.draw.rect(screen, colour[4], my_rect)
pygame.draw.rect(screen, colour[5], bottomrect_1)
pygame.draw.rect(screen, colour[5], bottomrect_2)
pygame.display.update()
clock.tick(60)
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Answer
Calculate the height of the diagonal rectangle on the right edge of the moving rectangle (my_rect.right):
dia_height = D_rect.height * (my_rect.right-D_rect.left) / D_rect.width
Compute the top of the the diagonal rectangle on the right edge of the moving rectangle:
D_rect_top = D_rect.bottom - round(dia_height)
The top of the the diagonal rectangle on the right edge of the moving rectangle is the bottom of the moving rectangle:
my_rect.bottom = D_rect_top
If the diagonal is in the opposite direction, find the height of the diagonal on the left edge (my_rect.left) instead of the right edge (my_rect.right).
The formula y = mx + b is hidden in this code:
x is my_rect.right - D_rect.left
m is -D_rect.height / D_rect.width
b is D_rect.bottom
y is my_rect.bottom
while True:
# [...]
if my_rect.colliderect(D_rect):
dia_height = D_rect.height * (my_rect.right-D_rect.left) / D_rect.width
D_rect_top = D_rect.bottom - round(dia_height)
my_rect.bottom = D_rect_top
# [....]