哪些是现代的 glTranslate 和 glRotate 替代品？

Question

重要编辑：我正在使用 OpenGL 的 PyOpenGL 绑定我试图不使用 glRotate and glTranslate 函数，但我还没有找到这两个函数的替代方法。此功能已弃用。我可以使用什么？

Answer 1

现代的方法是编写 Shader program, to use Vertex Array Objects and to use Uniform 个类型为 mat4 的变量。
与已弃用的固定函数管道相比，要编写的代码更多，但与通过 glBegin/glEnd 序列绘制相比，其好处是灵活性高且性能好得多。

对于矩阵计算，可以使用 PyGLM library, which is the python version of the c++ OpenGL Mathematics (glm) 库。

例如围绕 z 轴的缩放、旋转矩阵 angle 和平移可以设置为：

model = glm.mat4(1)
model = glm.translate(model, glm.vec3(0.2, 0.2, 0))
model = glm.rotate(model, angle, glm.vec3(0, 0, 1))
model = glm.scale(model, glm.vec3(0.5, 0.5, 1))

与 Legacy OpenGL operation glRoatate 相比，角度必须以弧度为单位设置。
请注意，除了使用 PyGLM，还可以使用流行的 NumPy library and numpy.matrix，但 PyGLM 更接近于您从 Legacy OpenGL 和函数 glScale、glTranslate 和 glRotate.
当然也可以不使用任何库来设置 4x4 矩阵，也可以自己实现矩阵运算。

查看小示例程序，其中使用PyOpenGL and PyGLM (beside the modules math and ctypes):

import math 
import ctypes
import glm 
from OpenGL.GLUT import *
from OpenGL.GL import *
from OpenGL.GL.shaders import *

class MyWindow:

    __caption = 'OpenGL Window'
    __vp_size = [800, 600]
    __vp_valid = False
    __glut_wnd = None

    __glsl_vert = """
        #version 450 core

        layout (location = 0) in vec3 a_pos;
        layout (location = 1) in vec4 a_col;

        out vec4 v_color;

        layout (location = 0) uniform mat4 u_proj; 
        layout (location = 1) uniform mat4 u_view; 
        layout (location = 2) uniform mat4 u_model; 

        void main()
        {
            v_color     = a_col;
            gl_Position = u_proj * u_view * u_model * vec4(a_pos.xyz, 1.0);
        }
    """

    __glsl_frag = """
        #version 450 core

        out vec4 frag_color;
        in  vec4 v_color;

        void main()
        {
            frag_color = v_color;
        }
    """

    __program = None
    __vao = None
    __vbo = None

    def __init__(self, w, h):

        self.__vp_size = [w, h]

        glutInit()
        glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
        glutInitWindowSize(self.__vp_size[0], self.__vp_size[1])
        __glut_wnd = glutCreateWindow(self.__caption)

        self.__program = compileProgram( 
            compileShader( self.__glsl_vert, GL_VERTEX_SHADER ),
            compileShader( self.__glsl_frag, GL_FRAGMENT_SHADER ),
        )

        attribures = [
        #    x       y    z    R  G  B  A
            -0.866, -0.5, 0,   1, 0, 0, 1, 
             0.866, -0.5, 0,   1, 1, 0, 1,
             0,      1.0, 0,   0, 0, 1, 1
        ]
        vertex_attributes = (GLfloat * len(attribures))(*attribures)
        itemsize = ctypes.sizeof(ctypes.c_float)

        self.__vbo = glGenBuffers(1)
        glBindBuffer(GL_ARRAY_BUFFER, self.__vbo)
        glBufferData(GL_ARRAY_BUFFER, vertex_attributes, GL_STATIC_DRAW)

        self.__vao = glGenVertexArrays(1)
        glBindVertexArray(self.__vao)
        glVertexAttribPointer(0, 3, GL_FLOAT, False, 7*itemsize, None)
        glEnableVertexAttribArray(0)
        glVertexAttribPointer(1, 4, GL_FLOAT, False, 7*itemsize, ctypes.c_void_p(3*itemsize))
        glEnableVertexAttribArray(1)

        glUseProgram(self.__program)

        glutReshapeFunc(self.__reshape)
        glutDisplayFunc(self.__mainloop)

    def run(self):
        self.__starttime = 0
        self.__starttime = self.elapsed_ms()
        glutMainLoop()

    def elapsed_ms(self):
      return glutGet(GLUT_ELAPSED_TIME) - self.__starttime

    def __reshape(self, w, h):
        self.__vp_valid = False

    def __mainloop(self):

        if not self.__vp_valid:
            self.__vp_size = [glutGet(GLUT_WINDOW_WIDTH), glutGet(GLUT_WINDOW_HEIGHT)]
            self.__vp_valid = True
            glViewport(0, 0, self.__vp_size[0], self.__vp_size[1])

        proj  = glm.mat4(1)
        view  = glm.mat4(1)
        model = glm.mat4(1)

        aspect = self.__vp_size[0]/self.__vp_size[1]
        aspect_x = aspect if self.__vp_size[0] > self.__vp_size[1] else 1.0
        aspect_y = 1/aspect if self.__vp_size[0] < self.__vp_size[1] else 1.0 
        proj = glm.ortho(-aspect_x, aspect_x, -aspect_y, aspect_y, -1.0, 1.0)

        angle = self.elapsed_ms() * math.pi * 2 / 3000.0
        model = glm.translate(model, glm.vec3(0.2, 0.2, 0))
        model = glm.rotate(model, angle, glm.vec3(0, 0, 1))
        model = glm.scale(model, glm.vec3(0.5, 0.5, 1))

        glUniformMatrix4fv(0, 1, GL_FALSE, glm.value_ptr(proj) )
        glUniformMatrix4fv(1, 1, GL_FALSE, glm.value_ptr(view) )
        glUniformMatrix4fv(2, 1, GL_FALSE, glm.value_ptr(model) )

        glClearColor(0.2, 0.3, 0.3, 1.0)
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)

        glDrawArrays(GL_TRIANGLES, 0, 3)

        glutSwapBuffers()
        glutPostRedisplay()


window = MyWindow(800, 600)
window.run()

哪些是现代的 glTranslate 和 glRotate 替代品？

Which are the modern glTranslate and glRotate alternatives?

python

opengl

pyopengl

python-3.x