Blender下用Python实现模型文件导入、渲染和动画生成

为了让数值计算的结果能够有更好的渲染效果，这段时间一直在用Blender这个开源软件来处理计算结果。

因为是处理大量数据的计算结果，所以不得不考虑用Python编写脚本来实现批量处理，编写过程中，Google帮我解决了大部分实现过程中的障碍，下面是完整的实现过程：

1. 将计算结果的mesh文件导入到Blender中；

   import bpy 
   import os 
   
   # folder path to save rendered image
   in_dir = "E:\\SPH\\Paper 01\\D18\\"
   lst = os.listdir(in_dir)
   
   # folder path for importing data files
   in_dir_ply = "E:\\SPH\\Paper 01\\D18\\Ply_batch\\"
   lst_ply = os.listdir(in_dir_ply)
   
   # folder path to save rendered animation
   out_dir = "E:\\SPH\\Paper 01\\D18\\test.avi"
   
   # Filter file list by valid file types.
   candidates = []
   candidates_name = []
   c = 0
   for item in lst_ply:
       fileName, fileExtension = os.path.splitext(lst_ply[c])
       if fileExtension == ".ply":
           candidates.append(item)
           candidates_name.append(fileName)
       c = c + 1
   
   file = [{"name":i} for i in candidates]   
   n = len(file)
   print(n) 
   
   # To import mesh.ply in batches
   for i in range (0,n):
       bpy.ops.import_mesh.ply(filepath=candidates[n], files=[file[n]], directory=in_dir_ply, filter_glob="*.ply")
       bpy.data.objects[candidates_name[i]].hide = True
       bpy.data.objects[candidates_name[i]].hide_render = True

2. 在Blender中进行批量渲染并保存成图片文件；（这里用到了提前制作好的材质文件“Material.001”）

   # Set file_format for render images
   bpy.data.scenes["Scene"].render.image_settings.file_format = 'PNG'
   
   # To render and save rendered images
   for i in range (0,n):
       bpy.data.objects[candidates_name[i]].hide = False    #objects must be visible to use modifier
       bpy.data.objects[candidates_name[i]].hide_render = False    #objects must be renderable to export render image
       bpy.context.scene.objects.active = bpy.data.objects[candidates_name[i]] #get object
       bpy.ops.object.modifier_add(type='PARTICLE_SYSTEM')    #add modifier as particle_system
       bpy.data.objects[candidates_name[i]].particle_systems['ParticleSystem'].settings = bpy.data.particles['ParticleSettings'] #assign particle settings to object's particle system
       bpy.data.objects[candidates_name[i]].data.materials.append(bpy.data.materials["Material.001"])    #assign existed material to active object.
       bpy.data.scenes["Scene"].render.filepath = '//%02d'%(i)    #set save filepath
       bpy.ops.render.render( write_still=True )    #render and save
       bpy.data.objects[candidates_name[i]].hide = True    #hide again for next image rendering
       bpy.data.objects[candidates_name[i]].hide_render = True    #hide again for next image rendering

3. 在Blender的Video Sequence Editor (VSE)中插入上一步生成的渲染后的图片文件；

   # Active VSE to generate rendering animation
   bpy.data.scenes["Scene"].render.use_sequencer = True
   
   # Filter file list by valid file types.
   re_image = []
   re_image_name = []
   c = 0
   for item in lst:
       fileName, fileExtension = os.path.splitext(lst[c])
       if fileExtension == ".png":
           re_image.append(item)
           re_image_name.append(fileName)
       c = c + 1
   
   # Create the sequencer data
   bpy.context.scene.sequence_editor_create()
   
   # Add strip into VSE by importing new image
   for i in range (0,n):
       bpy.context.scene.sequence_editor.sequences.new_image(
           name=re_image[i],
           filepath=os.path.join(in_dir, re_image[i]),
           channel=1, frame_start=i)

4. 在Blender中生成并保存动画文件。

   # Resolution settings for animation
   resx = 720; #1920 
   resy = 480; #1080 
   bpy.data.scenes["Scene"].render.resolution_x = resx 
   bpy.data.scenes["Scene"].render.resolution_y = resy 
   bpy.data.scenes["Scene"].render.resolution_percentage = 100 
   
   bpy.data.scenes["Scene"].frame_end = n 
   bpy.data.scenes["Scene"].render.image_settings.file_format = 'AVI_JPEG' 
   bpy.data.scenes["Scene"].render.filepath = out_dir
   bpy.ops.render.render( animation=True )