FlatVersusGouraud 对比平面着色和高洛德着色

一：主要的知识点

1、说明

本文只是教程内容的一小段，因博客字数限制，故进行拆分。主教程链接：vtk教程------逐行解析官网所有Python示例-CSDN博客

2、知识点纪要

本段代码主要涉及的有①平面着色与高洛德着色的区别

二：代码及注释

import vtkmodules.vtkRenderingOpenGL2
import vtkmodules.vtkInteractionStyle
from vtkmodules.vtkCommonColor import vtkNamedColors
from vtkmodules.vtkIOGeometry import vtkOBJReader
from vtkmodules.vtkFiltersSources import vtkSphereSource, vtkCylinderSource
from collections import OrderedDict
from vtkmodules.vtkRenderingCore import vtkPolyDataMapper, vtkActor, vtkRenderer, vtkRenderWindow, \
    vtkRenderWindowInteractor
from vtkmodules.vtkCommonDataModel import vtkQuadric
from vtkmodules.vtkImagingHybrid import vtkSampleFunction
from vtkmodules.vtkFiltersCore import vtkContourFilter


def CreateIsoSurface(flat):
    quadric = vtkQuadric()
    quadric.SetCoefficients(1, 2, 3, 0, 1, 0, 0, 0, 0, 0)
    sample = vtkSampleFunction()
    sample.SetSampleDimensions(25, 25, 25)
    sample.SetImplicitFunction(quadric)
    # Generate the implicit surface.
    contour = vtkContourFilter()
    contour.SetInputConnection(sample.GetOutputPort())
    range = [1.0, 6.0]
    contour.GenerateValues(5, range)
    # Map the contour.
    contourMapper = vtkPolyDataMapper()
    contourMapper.SetInputConnection(contour.GetOutputPort())
    contourMapper.SetScalarRange(0, 7)
    actor = vtkActor()
    actor.SetMapper(contourMapper)
    if flat:
        actor.GetProperty().SetInterpolationToFlat()
    else:
        actor.GetProperty().SetInterpolationToGouraud()
    renderer = vtkRenderer()
    renderer.AddActor(actor)
    return renderer


def CreateModel(flat, fileName):
    '''

    :param flat: The interpolation to use (flat or Gouraud).
    :param fileName: The file name.
    :return: the renderer
    '''
    colors = vtkNamedColors()
    reader = vtkOBJReader()
    reader.SetFileName(fileName)
    mapper = vtkPolyDataMapper()
    mapper.SetInputConnection(reader.GetOutputPort())
    actor = vtkActor()
    actor.SetMapper(mapper)
    actor.GetProperty().SetColor(colors.GetColor3d('Tan'))
    if flat:
        actor.GetProperty().SetInterpolationToFlat()
    else:
        actor.GetProperty().SetInterpolationToGouraud()
    renderer = vtkRenderer()
    renderer.AddActor(actor)
    return renderer


def CreateCylinder(flat):
    colors = vtkNamedColors()
    cylinder = vtkCylinderSource()
    mapper = vtkPolyDataMapper()
    mapper.SetInputConnection(cylinder.GetOutputPort())
    actor = vtkActor()
    actor.SetMapper(mapper)
    actor.GetProperty().SetColor(colors.GetColor3d('MistyRose'))
    if flat:
        actor.GetProperty().SetInterpolationToFlat()
    else:
        actor.GetProperty().SetInterpolationToGouraud()
    renderer = vtkRenderer()
    renderer.AddActor(actor)
    return renderer


def CreateSphere(flat):
    colors = vtkNamedColors()

    sphere = vtkSphereSource()
    mapper = vtkPolyDataMapper()
    mapper.SetInputConnection(sphere.GetOutputPort())

    actor = vtkActor()
    actor.SetMapper(mapper)
    actor.GetProperty().SetColor(colors.GetColor3d('MistyRose'))

    if flat:

        actor.GetProperty().SetInterpolationToFlat()
    else:
        actor.GetProperty().SetInterpolationToGouraud()

    renderer = vtkRenderer()
    renderer.AddActor(actor)
    return renderer


def main():
    """
    平面着色 SetInterpolationToFlat
    原理: 对多边形（三角形或四边形）的整个表面使用一个恒定的颜色和法向量计算亮度
    视觉效果: 结果是棱角分明的。可以看到组成曲面的各个多边形的边界，常用于显示模型的实际拓扑结构或模拟低多边形艺术风格

    高洛德着色 SetInterpolationToGouraud
    原理: 在多边形的顶点处计算颜色和亮度，然后将这些颜色值在多边形内部进行线性插值
    视觉效果: 结果是平滑且连续的。它极大地减少了多边形边缘的可见性，使低分辨率的曲面看起来更圆滑，更逼真
    """
    colors = vtkNamedColors()

    fileName = "Data/cow.obj"

    renderers = OrderedDict()
    renderers['flatSphereRenderer'] = CreateSphere(True)
    renderers['flatCylinderRenderer'] = CreateCylinder(True)
    renderers['flatIsoSurfaceRenderer'] = CreateIsoSurface(True)
    renderers['flatModelRenderer'] = CreateModel(True, fileName)

    renderers['smoothSphereRenderer'] = CreateSphere(False)
    renderers['smoothCylinderRenderer'] = CreateCylinder(False)
    renderers['smoothIsoSurfaceRenderer'] = CreateIsoSurface(False)
    renderers['smoothModelRenderer'] = CreateModel(False, fileName)

    keys = list(renderers.keys())

    renderWindow = vtkRenderWindow()

    # Setup the viewports for the renderers.
    rendererSize = 256
    xGridDimensions = 4
    yGridDimensions = 2

    renderWindow.SetSize(rendererSize * xGridDimensions, rendererSize * yGridDimensions)
    renderWindow.SetWindowName('FlatVersusGouraud')

    for row in range(0, yGridDimensions):
        for col in range(0, xGridDimensions):
            # (xmin, ymin, xmax, ymax)
            viewport = [0] * 4
            viewport[0] = col / xGridDimensions
            viewport[1] = (yGridDimensions - (row + 1)) / yGridDimensions
            viewport[2] = (col + 1) / xGridDimensions
            viewport[3] = (yGridDimensions - row) / yGridDimensions
            index = row * xGridDimensions + col
            renderers[keys[index]].SetViewport(viewport)

    for r in range(0, len(renderers)):
        renderers[keys[r]].SetBackground(colors.GetColor3d('SlateGray'))
        renderers[keys[r]].GetActiveCamera().Azimuth(20)
        renderers[keys[r]].GetActiveCamera().Elevation(30)
        renderers[keys[r]].ResetCamera()
        if r > 3:
            renderers[keys[r]].SetActiveCamera(renderers[keys[r - 4]].GetActiveCamera())

        renderWindow.AddRenderer(renderers[keys[r]])

    interactor = vtkRenderWindowInteractor()
    interactor.SetRenderWindow(renderWindow)

    renderWindow.Render()
    interactor.Start()

if __name__ == '__main__':
    main()