python之OpenGL应用（五）变换

变换是指平移、旋转、缩放等操作，在Python代码中完成这些操作，需要安装相应的库。

1 安装PyGLM

OpenGL Mathematics(GLM )是一个基于GLSL的数学运算库，其GitHub站点为：g-truc/glm: OpenGL Mathematics (GLM) (github.com)

PyGLM是GLM的Python绑定，其GitHub站点为：Zuzu-Typ/PyGLM: Fast OpenGL Mathematics (GLM) for Python (github.com)

PyGLM的PyPi地址为：PyGLM · PyPI

使用之前，需要通过下面的pip命令安装：

bash 复制代码

pip install PyGLM

2 设置变换矩阵

OpenGL的变换操作主要通过变换矩阵实现，对应的代码如下：

python 复制代码

import numpy as np
import glfw
import glm

#创建变换矩阵
trans = glm.mat4(1.0)
#平移，范围在-0.5到0.5之间
trans = glm.translate(trans, glm.vec3(0.5, -0.5, 0.0) * np.sin(glfw.get_time()))
#绕z轴旋转
trans = glm.rotate(trans, glfw.get_time(), glm.vec3(0.0, 0.0, 1.0))
#缩放，范围在0.5-1.0之间
trans = glm.scale(trans, glm.vec3(1.0, 1.0, 0.0) * (np.sin(glfw.get_time()) * 0.5 + 0.5))

接着，新建一个顶点着色器文件transform.vs.glsl，将变换矩阵与坐标结合：

cpp 复制代码

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColor;
layout (location = 2) in vec2 aTexCoord;
 
out vec3 ourColor;
out vec2 TexCoord;
 
uniform mat4 transform;
 
void main()
{
    gl_Position = transform * vec4(aPos, 1.0);
    ourColor = aColor;
    TexCoord = aTexCoord;
}

对应的片段着色器文件transform.fs.glsl：

cpp 复制代码

#version 330 core
out vec4 FragColor;
 
in vec3 ourColor;
in vec2 TexCoord;
 
uniform sampler2D texture1;
uniform sampler2D texture2;
 
void main()
{
    FragColor = mix(texture(texture1, TexCoord), texture(texture2, TexCoord), 0.2);
}

3 完整的代码

python 复制代码

import glfw as glfw
from OpenGL.GL import *
import numpy as np
from PIL.Image import open
import glm as glm
 
import shader as shader
 
glfw.init()
window = glfw.create_window(800, 600, "shader", None, None)
glfw.make_context_current(window)
 
VAO = glGenVertexArrays(1)
glBindVertexArray(VAO)

vertices = np.array([   # 位置               颜色
                     0.5, -0.5, 0.0,  1.0, 0.0, 0.0, 1.0, 0.0,  # 右下
                    -0.5, -0.5, 0.0,  0.0, 1.0, 0.0, 0.0, 0.0,  # 左下
                     0.0,  0.5, 0.0,  0.0, 0.0, 1.0, 0.5, 1.0,  # 顶部
                    ])

VBO = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, VBO)
glBufferData(GL_ARRAY_BUFFER, 8 * vertices.size, vertices, GL_STATIC_DRAW)
glVertexAttribPointer(0, 3, GL_DOUBLE, GL_FALSE, int(8 * 8), None)
glEnableVertexArrayAttrib(VAO, 0)
glVertexAttribPointer(1, 3, GL_DOUBLE, GL_FALSE, int(8 * 8), ctypes.c_void_p(8 * 3))
glEnableVertexArrayAttrib(VAO, 1)

#纹理设置
glVertexAttribPointer(2, 2, GL_DOUBLE, GL_FALSE, int(8 * 8), ctypes.c_void_p(8 * 6))
glEnableVertexArrayAttrib(VAO, 2)
 
image = open('images\container.jpg')
texture = glGenTextures(1)
glBindTexture(GL_TEXTURE_2D, texture)
# 为当前绑定的纹理对象设置环绕、过滤方式
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
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_RGB, image.size[0], image.size[1], 0, GL_RGB, GL_UNSIGNED_BYTE, image.tobytes())
glGenerateMipmap(GL_TEXTURE_2D)
 
shader = shader.Shader("./glsl/transform.vs.glsl", "./glsl/transform.fs.glsl")
 
while not glfw.window_should_close(window):
    glClearColor(0.2, 0.3, 0.3, 1.0)
    glClear(GL_COLOR_BUFFER_BIT)
 
    trans = glm.mat4(1.0)
    trans = glm.translate(trans, glm.vec3(0.5, -0.5, 0.0)*np.sin(glfw.get_time()))
    trans = glm.rotate(trans, glfw.get_time(), glm.vec3(0.0, 0.0, 1.0))
    trans = glm.scale(trans, glm.vec3(1.0, 1.0, 0.0)*(np.sin(glfw.get_time())*0.5+0.5))
 
    shader.use()
    glUniformMatrix4fv(glGetUniformLocation(shader.shaderProgram, 'transform'), 1, GL_FALSE, glm.value_ptr(trans))
 
    glBindVertexArray(VAO)
    glActiveTexture(GL_TEXTURE0)  # 在绑定纹理之前先激活纹理单元
    glBindTexture(GL_TEXTURE_2D, texture)
    glDrawArrays(GL_TRIANGLES, 0, 3)
    glfw.swap_buffers(window)
    glfw.poll_events()
 
shader.delete()

运行结果：

20260315_194424

参考资料：

基于Python的OpenGL 04 之变换 - 当时明月在曾照彩云归 - 博客园

变换 - LearnOpenGL CN