Is there a way to change the location and size of an imported .obj file in Pygame?

北慕城南 提交于 2021-01-28 03:25:54

问题


I created an .obj file using blender and loaded into Pygame using the OBJfileloader as sugested by skrx in: Error in OBJFileLoader

Is there an easy way to change the location, height and width of the imported .obj file after importing it into Pygame? As an example, if you create a tree.obj file, to be able to place that same tree in different places with different sizes?

Following the code below, maybe something like:

object_obj = OBJ("Tree.obj", swapyz=False)

object_obj.setX = 0

object_obj.setWidth = 3

object_obj.setHeight =10

Or by sending extra parameters to the obj loader, changing the vertices?

OBJ Loader:

import pygame
from OpenGL.GL import *

def MTL(filename):
    filename = 'OBJ/'+filename
    contents = {}
    mtl = None
    for line in open(filename, "r"):
        if line.startswith('#'): continue
        values = line.split()
        if not values: continue
        if values[0] == 'newmtl':
            mtl = contents[values[1]] = {}
        elif mtl is None:
            raise ValueError("mtl file doesn't start with newmtl stmt")
        elif values[0] == 'map_Kd':
            # load the texture referred to by this declaration
            mtl[values[0]] = values[1]
            surf = pygame.image.load(mtl['map_Kd'])
            image = pygame.image.tostring(surf, 'RGBA', 1)
            ix, iy = surf.get_rect().size
            texid = mtl['texture_Kd'] = glGenTextures(1)
            glBindTexture(GL_TEXTURE_2D, texid)
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
                GL_LINEAR)
            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
                GL_LINEAR)
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, ix, iy, 0, GL_RGBA,
                GL_UNSIGNED_BYTE, image)
        else:
            mtl[values[0]] = list(map(float, values[1:]))
    return contents

class OBJ:
    def __init__(self, filename, swapyz=False):
        """Loads a Wavefront OBJ file. """
        self.vertices = []
        self.normals = []
        self.texcoords = []
        self.faces = []

        material = None
        for line in open(filename, "r"):
            if line.startswith('#'): continue
            values = line.split()
            if not values: continue
            if values[0] == 'v':
                v = list(map(float, values[1:4]))
                if swapyz:
                    v = v[0], v[2], v[1]
                self.vertices.append(v)
            elif values[0] == 'vn':
                v = list(map(float, values[1:4]))
                if swapyz:
                    v = v[0], v[2], v[1]
                self.normals.append(v)
            elif values[0] == 'vt':
                self.texcoords.append(list(map(float, values[1:3])))
            elif values[0] in ('usemtl', 'usemat'):
                material = values[1]
            elif values[0] == 'mtllib':
                self.mtl = MTL(values[1])
            elif values[0] == 'f':
                face = []
                texcoords = []
                norms = []
                for v in values[1:]:
                    w = v.split('/')
                    face.append(int(w[0]))
                    if len(w) >= 2 and len(w[1]) > 0:
                        texcoords.append(int(w[1]))
                    else:
                        texcoords.append(0)
                    if len(w) >= 3 and len(w[2]) > 0:
                        norms.append(int(w[2]))
                    else:
                        norms.append(0)
                self.faces.append((face, norms, texcoords, material))

        self.gl_list = glGenLists(1)
        glNewList(self.gl_list, GL_COMPILE)
        glEnable(GL_TEXTURE_2D)
        glFrontFace(GL_CCW)
        for face in self.faces:
            vertices, normals, texture_coords, material = face

            mtl = self.mtl[material]
            if 'texture_Kd' in mtl:
                # use diffuse texmap
                glBindTexture(GL_TEXTURE_2D, mtl['texture_Kd'])
            else:
                # just use diffuse colour
                glColor(*mtl['Kd'])

            glBegin(GL_POLYGON)
            for i in range(len(vertices)):
                if normals[i] > 0:
                    glNormal3fv(self.normals[normals[i] - 1])
                if texture_coords[i] > 0:
                    glTexCoord2fv(self.texcoords[texture_coords[i] - 1])
                glVertex3fv(self.vertices[vertices[i] - 1])
            glEnd()
        glDisable(GL_TEXTURE_2D)
        glEndList()

Displaying .OBJ file in Pygame:

# Basic OBJ file viewer. needs objloader from:
#  http://www.pygame.org/wiki/OBJFileLoader
# LMB + move: rotate
# RMB + move: pan
# Scroll wheel: zoom in/out
import sys, pygame
from pygame.locals import *
from pygame.constants import *
from OpenGL.GL import *
from OpenGL.GLU import *

# IMPORT OBJECT LOADER
from OBJ_Loader import *

pygame.init()
viewport = (800,600)
hx = viewport[0]/2
hy = viewport[1]/2
srf = pygame.display.set_mode(viewport, OPENGL | DOUBLEBUF)

glLightfv(GL_LIGHT0, GL_POSITION,  (-40, 200, 100, 0.0))
glLightfv(GL_LIGHT0, GL_AMBIENT, (0.2, 0.2, 0.2, 1.0))
glLightfv(GL_LIGHT0, GL_DIFFUSE, (0.5, 0.5, 0.5, 1.0))
glEnable(GL_LIGHT0)
glEnable(GL_LIGHTING)
glEnable(GL_COLOR_MATERIAL)
glEnable(GL_DEPTH_TEST)
glShadeModel(GL_SMOOTH)           # most obj files expect to be smooth-shaded

# LOAD OBJECT AFTER PYGAME INIT
object_obj = OBJ("Tree.obj", swapyz=False)
clock = pygame.time.Clock()

glMatrixMode(GL_PROJECTION)
glLoadIdentity()
width, height = viewport
gluPerspective(90, 1, 0.001, 1000.0)
glEnable(GL_DEPTH_TEST)
glMatrixMode(GL_MODELVIEW)

rx, ry = (0,0)
tx, ty = (0,0)
zpos = 1
rotate = move = False
while 1:
    clock.tick(30)
    for e in pygame.event.get():
        if e.type == QUIT:
            sys.exit()
        elif e.type == KEYDOWN and e.key == K_ESCAPE:
            sys.exit()
        elif e.type == MOUSEBUTTONDOWN:
            if e.button == 4: zpos = max(1, zpos-1)
            elif e.button == 5: zpos += 1
            elif e.button == 1: rotate = True
            elif e.button == 3: move = True
        elif e.type == MOUSEBUTTONUP:
            if e.button == 1: rotate = False
            elif e.button == 3: move = False
        elif e.type == MOUSEMOTION:
            i, j = e.rel
            if rotate:
                rx += i
                ry += j
            if move:
                tx += i
                ty -= j

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    glLoadIdentity()

    # RENDER OBJECT
    glTranslate(tx/20., ty/20., - zpos)
    glRotate(ry, 1, 0, 0)
    glRotate(rx, 0, 1, 0)
    glCallList(obj.gl_list)


    pygame.display.flip()

回答1:


Do not change the vertex coordinates. Use glTranslate and glScale to define a model transformation.

Compute the Axis Aligned Bounding Box, when the vertex coordinates are read:

class OBJ:
    def __init__(self, filename, swapyz=False):
        """Loads a Wavefront OBJ file. """
        self.vertices = []
        self.normals = []
        self.texcoords = []
        self.faces = []

        self.min_v = [float("inf"), float("inf"), float("inf")]
        self.max_v = [-float("inf"), -float("inf"), -float("inf")]

        material = None
        for line in open(filename, "r"):
            if line.startswith('#'): continue
            values = line.split()
            if not values: continue
            if values[0] == 'v':
                v = list(map(float, values[1:4]))
                if swapyz:
                    v = v[0], v[2], v[1]

                for i in range(3):
                    self.min_v[i] = min(self.min_v[i], v[i])
                    self.max_v[i] = max(self.max_v[i], v[i])

                self.vertices.append(v)
            # [...]

        self.size = [self.max_v[i]-self.min_v[i] for i in range(3)]
        # [...]

Scale and translate the object when it is drawn. Use glPushMatrix / glPopMatrix to save and restore the current matrix before and after the transformations:

# RENDER OBJECT
glTranslate(tx/20., ty/20., - zpos)
glRotate(ry, 1, 0, 0)
glRotate(rx, 0, 1, 0)

pos = [0, 0, -5]
size = [3, 3, 10]
scale = [size[i]/obj.size[i] for i in range(3)]

glPushMatrix()
glTranslate(*pos)
glScale(*scale)
glCallList(obj.gl_list)
glPopMatrix()

Alternatively that can be done in the display list, too:

self.gl_list = glGenLists(1)
glNewList(self.gl_list, GL_COMPILE)
glEnable(GL_TEXTURE_2D)
glFrontFace(GL_CCW)

glPushMatrix()
glTranslate(*pos)
glScale(*scale)

for face in self.faces:
    vertices, normals, texture_coords, material = face
    # [...]

glDisable(GL_TEXTURE_2D)

glPopMatrix()
glEndList()


来源:https://stackoverflow.com/questions/59609837/is-there-a-way-to-change-the-location-and-size-of-an-imported-obj-file-in-pygam

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