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Isometric

Related Stack Overflow quest

Draw a staggered isometric map with python
Get isometric tile mouse selection in Pygame

📁 Minimal example - isometric grid

replit.com/@Rabbid76/Pygame-IsometircMap

Define the corner points of the map:

map_outline = [
    pygame.math.Vector2(left_x, left_y), 
    pygame.math.Vector2(top_x, top_y),
    pygame.math.Vector2(right_x, right_y,
    pygame.math.Vector2(bottom_x, bottom_y)
]

With this information you can calculate the x and y axis of the map:

origin = map_outline[0]
x_axis = (map_outline[1] - map_outline[0]) / columns
y_axis = (map_outline[3] - map_outline[0]) / rows

You can use the x-axis and the y-axis to calculate a point in the map as a function of the row and column:

def transform(p, mat2x2):
    x = p[0] * mat2x2[0][0] + p[1] * mat2x2[1][0]
    y = p[0] * mat2x2[0][1] + p[1] * mat2x2[1][1]
    return pygame.math.Vector2(x, y)

p_position = transform((column + 0.5, row + 0.5), (x_axis, y_axis)) + origin

If you want to get the row and column depending on the mouse cursor, you need to do the opposite. You need to calculate the inverse 2x2 matrix from the x and y axis. Using the inverse matrix, you can calculate the row and column as a function of a point on the map:

def inverseMat2x2(m):
    a, b, c, d = m[0].x, m[0].y, m[1].x, m[1].y
    det = 1 / (a*d - b*c)
    return [(d*det, -b*det), (-c*det, a*det)]

m_pos = pygame.mouse.get_pos()
m_grid_pos = transform(pygame.math.Vector2(m_pos) - origin, point_to_grid)
m_col, m_row = int(m_grid_pos[0]), int(m_grid_pos[1])