Panda3D: 从平面四个点创建长方体并渲染

from direct.showbase.ShowBase import ShowBase
from panda3d.core import Point3, Plane, Vec3

class MyApp(ShowBase):
    def __init__(self):
        ShowBase.__init__(self)
        
        # 已知平面的四个点
        p1 = Point3(0, 0, 0)
        p2 = Point3(0, 1, 0)
        p3 = Point3(1, 0, 0)
        p4 = Point3(1, 1, 0)
        
        # 计算平面的法向量
        plane = Plane(p1, p2, p3)
        normal = plane.getNormal()
        
        # 沿着法向量的方向拉伸出一个长方体
        length = 1
        width = 1
        height = 1
        forward = normal * length/2
        backward = -normal * length/2
        right = Vec3(0, 1, 0).cross(normal) * width/2
        left = -right
        up = normal.cross(right) * height/2
        down = -up
        
        # 计算长方体的8个顶点坐标
        vertex1 = p1 + forward + right + up
        vertex2 = p1 + forward + right + down
        vertex3 = p1 + forward + left + up
        vertex4 = p1 + forward + left + down
        vertex5 = p1 + backward + right + up
        vertex6 = p1 + backward + right + down
        vertex7 = p1 + backward + left + up
        vertex8 = p1 + backward + left + down
        
        # 创建平面和长方体的节点
        plane_node = self.render.attachNewNode('plane')
        cube_node = self.render.attachNewNode('cube')
        
        # 绘制平面
        plane_geom = self.createSquareGeom(p1, p2, p3, p4)
        plane_node.attachNewNode(plane_geom)
        plane_node.setColor(1, 1, 1, 1)
        plane_node.setP(-90)
        
        # 绘制长方体
        cube_geom = self.createCubeGeom(vertex1, vertex2, vertex3, vertex4, vertex5, vertex6, vertex7, vertex8)
        cube_node.attachNewNode(cube_geom)
        cube_node.setColor(1, 0, 0, 1)
        
        # 设置相机位置和朝向
        self.camera.setPos(0, -10, 0)
        self.camera.lookAt(0, 0, 0)
        
    def createSquareGeom(self, p1, p2, p3, p4):
        format = GeomVertexFormat.getV3()
        vertex_data = GeomVertexData('square', format, Geom.UHStatic)
        vertex_writer = GeomVertexWriter(vertex_data, 'vertex')
        vertex_writer.addData3f(p1)
        vertex_writer.addData3f(p2)
        vertex_writer.addData3f(p3)
        vertex_writer.addData3f(p4)
        
        tris = GeomTriangles(Geom.UHStatic)
        tris.addVertices(0, 1, 2)
        tris.addVertices(1, 3, 2)
        
        geom = Geom(vertex_data)
        geom.addPrimitive(tris)
        
        return geom
    
    def createCubeGeom(self, v1, v2, v3, v4, v5, v6, v7, v8):
        format = GeomVertexFormat.getV3()
        vertex_data = GeomVertexData('cube', format, Geom.UHStatic)
        vertex_writer = GeomVertexWriter(vertex_data, 'vertex')
        vertex_writer.addData3f(v1)
        vertex_writer.addData3f(v2)
        vertex_writer.addData3f(v3)
        vertex_writer.addData3f(v4)
        vertex_writer.addData3f(v5)
        vertex_writer.addData3f(v6)
        vertex_writer.addData3f(v7)
        vertex_writer.addData3f(v8)
        
        tris = GeomTriangles(Geom.UHStatic)
        tris.addVertices(0, 1, 2)
        tris.addVertices(1, 3, 2)
        tris.addVertices(0, 4, 5)
        tris.addVertices(0, 5, 1)
        tris.addVertices(1, 5, 7)
        tris.addVertices(1, 7, 3)
        tris.addVertices(3, 7, 6)
        tris.addVertices(3, 6, 2)
        tris.addVertices(2, 6, 4)
        tris.addVertices(2, 4, 0)
        tris.addVertices(4, 6, 5)
        tris.addVertices(5, 6, 7)
        
        geom = Geom(vertex_data)
        geom.addPrimitive(tris)
        
        return geom

app = MyApp()
app.run()