Re: [pygame] Code: Center of Triangle
Hi! I think he meant to take the square root. That would be the distance, which is the vector result of a 3 dimensional image... DR0ID wrote: > Hi > >> def CalculateDistance(a, b): >> x, y, z = b[0] - a[0], b[1] - a[1], b[2] - a[2] >> dist = x*x + y*y + z*z >> return dist * dist >> > > no offense, but "x*x + y*y + z*z" is already the distance squared, so > no need for "return dist*dist". (or did you do this on purpose?). > > ~DR0ID > > Uh, yeah, good catch. :-)
Re: [pygame] Code: Center of Triangle
DR0ID wrote: Hi def CalculateDistance(a, b): x, y, z = b[0] - a[0], b[1] - a[1], b[2] - a[2] dist = x*x + y*y + z*z return dist * dist no offense, but "x*x + y*y + z*z" is already the distance squared, so no need for "return dist*dist". (or did you do this on purpose?). ~DR0ID Uh, yeah, good catch. :-)
Re: [pygame] Code: Center of Triangle
Patrick Mullen wrote: Yeah, shouldn't it be math.sqrt(dist)? Although you might want to just return the distance^2 so the user can decide whether a sqrt is necessary or not. Yes -- often you don't need the sqrt, e.g. if you just want to compare two distances. Either way, the value you're calling 'dist' should really be called 'distsq' or something. -- Greg Ewing, Computer Science Dept, +--+ University of Canterbury, | Carpe post meridiem! | Christchurch, New Zealand | (I'm not a morning person.) | [EMAIL PROTECTED] +--+
Re: [pygame] Code: Center of Triangle
Yeah, shouldn't it be math.sqrt(dist)? Although you might want to just return the distance^2 so the user can decide whether a sqrt is necessary or not.
Re: [pygame] Code: Center of Triangle
Hi > > def CalculateDistance(a, b): > x, y, z = b[0] - a[0], b[1] - a[1], b[2] - a[2] > dist = x*x + y*y + z*z > return dist * dist > no offense, but "x*x + y*y + z*z" is already the distance squared, so no need for "return dist*dist". (or did you do this on purpose?). ~DR0ID
[pygame] Code: Center of Triangle
Worked this up today for myself, thought I'd post it in case someone
else found it useful.
import pygame
def CenterOfTriangle(A, B, C):
return (A[0] + B[0] + C[0])/3.0, (A[1] + B[1] + C[1])/3.0, (A[2] +
B[2] + C[2])/3.0
def CalculateDistance(a, b):
x, y, z = b[0] - a[0], b[1] - a[1], b[2] - a[2]
dist = x*x + y*y + z*z
return dist * dist
def NearestVert(triangle, pos):
distance =
v = -1
for i in range(len(triangle)):
temp = CalculateDistance(triangle[i], [pos[0], pos[1], 0])
if temp < distance:
distance = temp
v = i
assert(v >= 0)
return v
def main():
pygame.init()
screen = pygame.display.set_mode([640, 480], 0, 32)
quit = 0
triangle = [[132, 319, 0], [282, 120, 0], [434, 319, 0]]
center = CenterOfTriangle(*triangle)
v = -1
font = pygame.font.Font(None, 18)
pic = font.render('Center: %d, %d, %d Triangle: %s' %
(int(center[0]), int(center[1]), int(center[2]), triangle), 1, (0, 0, 0))
while not quit:
screen.fill((255, 255, 255))
pygame.draw.polygon(screen, (0, 0, 0), [triangle[0][:2],
triangle[1][:2], triangle[2][:2]], 1)
x, y, z = int(center[0]), int(center[1]), int(center[2])
screen.fill((255, 0, 0), [x-2, y-2, 4, 4])
screen.blit(pic, [0, 450])
pygame.display.flip()
pygame.event.pump()
for e in pygame.event.get():
if e.type == pygame.QUIT:
quit = 1
break
elif e.type == pygame.MOUSEBUTTONDOWN:
v = NearestVert(triangle, e.pos)
elif e.type == pygame.MOUSEMOTION:
if v > -1:
triangle[v] = [e.pos[0], e.pos[1], 0]
center = CenterOfTriangle(*triangle)
pic = font.render('Center: %d, %d, %d Triangle: %s'
% (int(center[0]), int(center[1]), int(center[2]), triangle), 1, (0, 0, 0))
elif e.type == pygame.MOUSEBUTTONUP:
v = -1
pygame.quit()
main()
