如何用Python修改Nuke的Contact Sheet实现EXR与HUD合并？

问题描述 #

我用Python脚本在Nuke里生成Contact Sheet，现有逻辑是把实体列表按30个一组拆分，给每个实体创建EXR的Read节点（路径为空时用Constant节点），再连到Contact Sheet。现在要优化成：每个实体同时创建EXR和HUD的Read节点，用Merge节点叠加后再连到Contact Sheet，但尝试时出现节点布局混乱、连接错误的问题，求解决实现流程和布局问题。

现有脚本代码：

def create_contact_sheet(self,entities, version_paths, first_frame,last_frame):
    movie_per_sheet = 30

    print ("no of movies per sheet:", movie_per_sheet)
    shot_list_splits = [entities[i:i + movie_per_sheet] for i in range(0, len(entities), movie_per_sheet)]
    print ("no of required sheets:", len(shot_list_splits))

    print("entities", entities)
    print("shot version split", version_paths)
    last_batch_rnode_pos = 0
    first_rnode_xpos = None
    r_node_xpos = None

    print('version map', version_paths)
    for sht_index, e_sht_list in enumerate(shot_list_splits):
        nodes_for_backdrop = []
        # create contact sheet:
        ctt_sheet = nuke.createNode("ContactSheet", "sheet_%s" %(sht_index + 1))
        print (">>> create ctt_sheet",ctt_sheet.name())
        nodes_for_backdrop.append(ctt_sheet)
        ctt_sheet["rows"].setValue(5)
        ctt_sheet["columns"].setValue(6)
        ctt_sheet["width"].setValue(5 * 1920)
        ctt_sheet["height"].setValue(6 * 1080)

        ctt_sheet.setSelected(False)

        for index, e_shot in enumerate(e_sht_list):
            exr_path = version_paths[e_shot][0]
            if exr_path == None:
                exr_r_node = nuke.createNode("Constant")
            else:
                exr_r_node = nuke.createNode("Read", "name %s file %s" % (e_shot, exr_path))
            nodes_for_backdrop.append(exr_r_node)
            r_node_xpos = last_batch_rnode_pos + index * 100
            exr_r_node["xpos"].setValue(r_node_xpos)
            exr_r_node["ypos"].setValue(0)
            exr_r_node['first'].setValue(first_frame)
            exr_r_node['last'].setValue(last_frame)
            ctt_sheet.setInput(index, exr_r_node)
            exr_r_node.setSelected(False)
            # store first node xpos to place ctt_sheet_xpos
            if index == 0:
                first_rnode_xpos = r_node_xpos

        # fix ctt_sheet_xpos
        ctt_sheet_xpos = (len(e_sht_list) * 100) / 2 + first_rnode_xpos
        ctt_sheet["xpos"].setValue(ctt_sheet_xpos)
        ctt_sheet["ypos"].setValue(300)

        last_batch_rnode_pos = r_node_xpos + 200
        self.create_back_drop(nodes_for_backdrop, ctt_sheet)

def create_back_drop(self, nodes, ctt_sheet):
    """
    make sure nodes were selected before execution this function
    """
    # select nodes
    for e_node in nodes:
        e_node.setSelected(True)

    node = nukescripts.autoBackdrop()
    node["label"].setValue(ctt_sheet.name())

    # de-select nodes
    for e_node in nodes:
        e_node.setSelected(False)

注：version_paths字典格式为{'实体名':[exr路径, hud路径]}，部分路径可能为None。

解决方案 #

修改思路 #

1. 为每个实体创建EXR节点、HUD节点，通过Merge节点（默认Over模式）叠加后再连接到Contact Sheet
2. 对每组节点（EXR、HUD、Merge）做纵向分层布局，横向保持统一偏移，避免节点重叠
3. 处理空路径情况：HUD路径为空时，直接将EXR节点作为Merge的输入，保证流程正常运行

修改后的完整代码 #

def create_contact_sheet(self, entities, version_paths, first_frame, last_frame):
    movie_per_sheet = 30

    print("no of movies per sheet:", movie_per_sheet)
    shot_list_splits = [entities[i:i + movie_per_sheet] for i in range(0, len(entities), movie_per_sheet)]
    print("no of required sheets:", len(shot_list_splits))

    print("entities", entities)
    print("shot version split", version_paths)
    last_batch_rnode_pos = 0
    first_rnode_xpos = None
    group_xpos = None

    print('version map', version_paths)
    for sht_index, e_sht_list in enumerate(shot_list_splits):
        nodes_for_backdrop = []
        # 创建Contact Sheet节点
        ctt_sheet = nuke.createNode("ContactSheet", f"sheet_{sht_index + 1}")
        print(f">>> create ctt_sheet {ctt_sheet.name()}")
        nodes_for_backdrop.append(ctt_sheet)
        ctt_sheet["rows"].setValue(5)
        ctt_sheet["columns"].setValue(6)
        ctt_sheet["width"].setValue(5 * 1920)
        ctt_sheet["height"].setValue(6 * 1080)
        ctt_sheet.setSelected(False)

        for index, e_shot in enumerate(e_sht_list):
            # 计算当前节点组的横向位置（扩大偏移量避免拥挤）
            group_xpos = last_batch_rnode_pos + index * 150
            # 1. 创建EXR节点
            exr_path = version_paths[e_shot][0]
            if exr_path is None:
                exr_r_node = nuke.createNode("Constant", f"name {e_shot}_EXR")
            else:
                exr_r_node = nuke.createNode("Read", f"name {e_shot}_EXR file {exr_path}")
            exr_r_node["xpos"].setValue(group_xpos)
            exr_r_node["ypos"].setValue(0)
            exr_r_node['first'].setValue(first_frame)
            exr_r_node['last'].setValue(last_frame)
            exr_r_node.setSelected(False)
            nodes_for_backdrop.append(exr_r_node)

            # 2. 创建HUD节点
            hud_path = version_paths[e_shot][1]
            hud_r_node = None
            if hud_path is not None:
                hud_r_node = nuke.createNode("Read", f"name {e_shot}_HUD file {hud_path}")
                hud_r_node["xpos"].setValue(group_xpos)
                hud_r_node["ypos"].setValue(100)
                hud_r_node['first'].setValue(first_frame)
                hud_r_node['last'].setValue(last_frame)
                hud_r_node.setSelected(False)
                nodes_for_backdrop.append(hud_r_node)

            # 3. 创建Merge节点并连接
            merge_node = nuke.createNode("Merge", f"name {e_shot}_Merge")
            merge_node["xpos"].setValue(group_xpos)
            merge_node["ypos"].setValue(200)
            merge_node.setSelected(False)
            nodes_for_backdrop.append(merge_node)

            # 连接Merge节点：A接EXR，B接HUD（HUD存在时）
            merge_node.setInput(0, exr_r_node)
            if hud_r_node is not None:
                merge_node.setInput(1, hud_r_node)

            # 将Merge节点连接到Contact Sheet的对应输入口
            ctt_sheet.setInput(index, merge_node)

            # 记录第一个节点组的位置，用于定位Contact Sheet
            if index == 0:
                first_rnode_xpos = group_xpos

        # 调整Contact Sheet的位置，使其居中于节点组上方
        ctt_sheet_xpos = (len(e_sht_list) * 150) / 2 + first_rnode_xpos
        ctt_sheet["xpos"].setValue(ctt_sheet_xpos)
        ctt_sheet["ypos"].setValue(350)  # 下移一点避免和Merge重叠

        # 更新下一批节点的起始位置
        last_batch_rnode_pos = group_xpos + 200
        # 创建背景板
        self.create_back_drop(nodes_for_backdrop, ctt_sheet)

def create_back_drop(self, nodes, ctt_sheet):
    """
    为节点创建背景板，需确保节点被选中
    """
    # 选中所有节点
    for e_node in nodes:
        e_node.setSelected(True)

    node = nukescripts.autoBackdrop()
    node["label"].setValue(ctt_sheet.name())

    # 取消选中
    for e_node in nodes:
        e_node.setSelected(False)

关键修改说明 #

• 节点布局：每个实体的节点组横向偏移index * 150（比原100大，避免拥挤），纵向分层：EXR在y=0，HUD在y=100，Merge在y=200，结构清晰不重叠
• 连接逻辑：Merge节点的A输入固定接EXR，B输入接HUD（路径非空时），最终将Merge输出连到Contact Sheet的对应输入口，替换原有的EXR直接连接
• 空路径处理：HUD路径为空时跳过HUD节点创建，Merge仅保留EXR输入，保证流程不中断
• Contact Sheet定位：根据节点组总宽度重新计算居中位置，并下移y坐标避免和Merge节点重叠
• 背景板范围：将HUD、Merge节点加入nodes_for_backdrop列表，确保所有相关节点都被包含在背景板内

内容的提问来源于stack exchange，提问作者Kartikey