对齐 pyOpenGL 中的单个对象以创建更大的聚合对象

Question

我正在尝试使用环面、圆柱体和长方体的组合在 PyOpenGL 中创建一个关键对象。我能够在 window 的中心分别获得这三个单独的对象，但是当我尝试将所有这些对象合并为一个 window 时，我无法做到这一点。

这是代码。

import pygame
from pygame.locals import *
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *

vertices = (
    (0.75, -0.25, -0.5),
    (0.75, 0.25, -0.5),
    (-0.75, 0.25, -0.5),
    (-0.75, -0.25, -0.5),
    (0.75, -0.25, 0.5),
    (0.75, 0.25, 0.5),
    (-0.75, -0.25, 0.5),
    (-0.75, 0.25, 0.5),
    )

edges = (
    (0,1),
    (0,3),
    (0,4),
    (2,1),
    (2,3),
    (2,7),
    (6,3),
    (6,4),
    (6,7),
    (5,1),
    (5,4),
    (5,7),
    )

surfaces = (
    (0,1,2,3),
    (3,2,7,6),
    (6,7,5,4),
    (4,5,1,0),
    (1,5,7,2),
    (4,0,3,6),
    )

colors = (
    (1,0,0),
    (0,1,0),
    (0,0,1),
    (0,0,0),
    (1,1,1),
    (0,1,1),
    )

def draw_cuboid():
    glBegin(GL_QUADS)
    for surface in surfaces:
        x = 0
        for vertex in surface:
            x+=1
            glColor3fv(colors[x])
            glVertex3fv(vertices[vertex])
    glEnd()

    glBegin(GL_LINES)
    for egde in edges:
        for vertex in egde:
            glVertex3fv(vertices[vertex])
    glEnd()

def draw_cylinder():
    glRotatef(1, 1, 1.25, 12.5)
    glColor3f(1.0, 1.0, 0.0)
    quadratic = gluNewQuadric()
    gluQuadricNormals(quadratic, GLU_SMOOTH)
    gluQuadricTexture(quadratic, GL_TRUE)
    gluCylinder(quadratic, 0.15, 0.15, 2.5, 32, 32)

def draw_torus():
    glColor3f(0.0, 1.0, 0.0)
    glutWireTorus(0.2, 0.8, 50, 50)

def main():
    pygame.init()
    glutInit()
    display = (800,600)
    pygame.display.set_mode(display, DOUBLEBUF|OPENGL)

    gluPerspective(75, (display[0]/display[1]), 0.1, 50.0)

    glTranslatef(0.0, 0.0, -5)

    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                quit()

            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_LEFT:
                    glTranslatef(-0.5, 0, 0)
                if event.key == pygame.K_RIGHT:
                    glTranslatef(0.5, 0, 0)

                if event.key == pygame.K_UP:
                    glTranslatef(0, 0.5, 0)
                if event.key == pygame.K_DOWN:
                    glTranslatef(0, -0.5, 0)

                if event.key == pygame.K_SPACE:
                    glRotatef(5, 0, 1, 0)   

            if event.type == pygame.MOUSEBUTTONDOWN:
                if event.button == 4:
                    glTranslatef(0, 0, 1.0)
                if event.button == 5:
                    glTranslatef(0, 0, -1.0)


        glRotatef(1, 3, 1, 1)
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)
        draw_cuboid()
        draw_torus()
        draw_cylinder()
        pygame.display.flip()
        pygame.time.wait(10)

main()

我为此得到的输出如下。 output

如您所见，所有三个对象都是从 window 的中心生成的。

如何更改它们的位置以获得类似对象的键，即中心的圆柱体（与 y 轴对齐），圆环体在其顶部，长方体在另一端的尖端？
如何让这个键与 y 轴对齐（默认情况下保持不变，不旋转），然后按下 space 键，我可以 start/stop 整个对象沿 y 轴旋转？

Answer 1

    glRotatef(1, 3, 1, 1)
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)

    glTranslate(0.9, 0, 2)
    draw_cuboid()
    glTranslate(-0.9, 0, -2)

    glRotate(90,1,0,0)
    glTranslate(0,-1,0)
    draw_torus()
    glTranslate(0, 1, 0);
    glRotate(-90, 1, 0, 0)

    draw_cylinder()
    pygame.display.flip()
    pygame.time.wait(10)

Answer 2

像 glRotatef, glScale and glTranslate 这样的矩阵运算定义一个矩阵并将当前矩阵乘以新矩阵。
如果必须对对象应用变换，则可以将模型矩阵乘以当前矩阵。如果此转换仅应用于单个对象，则在绘制对象后，可以将逆模型矩阵乘以当前矩阵。这会撤消转换。
但这不是执行此操作的预期方式。

通常的做法是在模型变换前先把当前矩阵存起来，画好物体后再恢复。因此，Legacy OpenGL 个矩阵组织在堆栈上。存储当前矩阵，可以将其压入堆栈。要恢复它，可以从堆栈中弹出它。

使用glPushMatrix/glPopMatrix存储和恢复当前矩阵。例如：

glRotatef(1, 3, 1, 1)
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)

glPushMatrix()
glTranslate(0.9, 0, 2)
draw_cuboid()
glPopMatrix()

glPushMatrix()
glRotate(90,1,0,0)
glTranslate(0,-1,0)
draw_torus()
glPopMatrix()

glPushMatrix()
draw_cylinder()
glPopMatrix()

pygame.display.flip()

请注意，不需要以相反的顺序执行逆矩阵运算，因为 glPopMatrix 始终与 glPushMatrix 相对。

进一步注意，存在多个不同的电流矩阵（参见 glMatrixMode）。 Ecah顶点坐标首先由模型视图矩阵（GL_MODELVIEW）转换。之后它被（GL_PROJECTION）投影矩阵变换。

建议将透视投影矩阵（gluPerspective）设置为GL_PROJECTION矩阵，视图和模型矩阵设置为GL_MODELVIEW矩阵：

display = (800,600)
pygame.display.set_mode(display, DOUBLEBUF|OPENGL)

glMatrixMode(GL_PROJECTION)
gluPerspective(75, (display[0]/display[1]), 0.1, 50.0)

glMatrixMode(GL_MODELVIEW)
glTranslatef(0, 0, -5)

另见 Scale, Rotate, Translate

最小示例：

import pygame
from pygame.locals import *
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *

vertices = ((0.75, -0.25, -0.5), (0.75, 0.25, -0.5), (-0.75, 0.25, -0.5), (-0.75, -0.25, -0.5),
    (0.75, -0.25, 0.5), (0.75, 0.25, 0.5), (-0.75, -0.25, 0.5), (-0.75, 0.25, 0.5))
edges = ((0,1), (0,3), (0,4), (2,1), (2,3), (2,7), (6,3), (6,4), (6,7), (5,1), (5,4), (5,7))
surfaces = ((0,1,2,3), (3,2,7,6), (6,7,5,4), (4,5,1,0), (1,5,7,2), (4,0,3,6))
colors = ((1,0,0), (0,1,0), (0,0,1), (0,0,0), (1,1,1), (0,1,1))

def draw_cuboid():
    glBegin(GL_QUADS)
    for surface in surfaces:
        x = 0
        for vertex in surface:
            x+=1
            glColor3fv(colors[x])
            glVertex3fv(vertices[vertex])
    glEnd()

    glBegin(GL_LINES)
    for egde in edges:
        for vertex in egde:
            glVertex3fv(vertices[vertex])
    glEnd()

def draw_cylinder():
    glRotatef(1, 1, 1.25, 12.5)
    glColor3f(1.0, 1.0, 0.0)
    quadratic = gluNewQuadric()
    gluQuadricNormals(quadratic, GLU_SMOOTH)
    gluQuadricTexture(quadratic, GL_TRUE)
    gluCylinder(quadratic, 0.15, 0.15, 2.5, 32, 32)

def draw_torus():
    glColor3f(0.0, 1.0, 0.0)
    glutWireTorus(0.2, 0.8, 50, 50)

def main():
    glutInit()
    pygame.init()
    glutCreateWindow(b"OpenGL Window") # prevent glutWireTorus OSError: exception: access violation reading 0x0000000000000034
    
    display = (400, 300)
    pygame.display.set_mode(display, DOUBLEBUF|OPENGL)
    glMatrixMode(GL_PROJECTION)
    gluPerspective(75, (display[0]/display[1]), 0.1, 50.0)
    glMatrixMode(GL_MODELVIEW)
    glTranslatef(0, 0, -5)

    while True:
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                quit()

            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_LEFT:
                    glTranslatef(-0.5, 0, 0)
                if event.key == pygame.K_RIGHT:
                    glTranslatef(0.5, 0, 0)
                if event.key == pygame.K_UP:
                    glTranslatef(0, 0.5, 0)
                if event.key == pygame.K_DOWN:
                    glTranslatef(0, -0.5, 0)
                if event.key == pygame.K_SPACE:
                    glRotatef(5, 0, 1, 0)   

            if event.type == pygame.MOUSEBUTTONDOWN:
                if event.button == 4:
                    glTranslatef(0, 0, 1.0)
                if event.button == 5:
                    glTranslatef(0, 0, -1.0)

        glRotatef(1, 3, 1, 1)
        glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)
        glPushMatrix()
        glTranslate(0.9, 0, 2)
        draw_cuboid()
        glPopMatrix()

        glPushMatrix()
        glRotate(90,1,0,0)
        glTranslate(0,-1,0)
        draw_torus()
        glPopMatrix()

        glPushMatrix()
        draw_cylinder()
        glPopMatrix()
        pygame.display.flip()
        pygame.time.wait(10)

main()

对齐 pyOpenGL 中的单个对象以创建更大的聚合对象

Align individual objects in pyOpenGL to create a bigger aggregated object

python

opengl

pygame

pyopengl

opengl-compat