blender中获取虚拟相机渲染图片上每像素对应的纹理上的像素值

示例图：

相机渲染出图后，图片上每个像素点中对应的纹理的像素值。获取这个对应关系存到数据库

基本思路是

从相机圆心发射射线接触到物体时获取接触点（三维坐标）所在三角面，通过这个三角面的三个顶点坐标及其三个纹理坐标，通过重心坐标求出接触点所对应的纹理坐标。在发射射线时，通过相机分辨率中某一点的二维坐标（即渲染出图后图片上的坐标）转三维坐标，结合相机圆心确认射线方向。至此【图片上每个像素点中对应的纹理的像素值】对应关系所需要的数据已具备，

示例代码

如上图，相机视野中存在一个半球模型（已贴图），一个模型船

import bpy
import mathutils
import sqlite3
import time
import numpy as np
from PIL import Image# 虚拟相机名称的变量，用与获取自定义命名方式的物体。
name = 'bow'
# 导出数据库位置
dbpath = 'D:/syncdisk/blender_export/' + name + '.db'
# 渲染出图的位置
export_image_path = 'D:/syncdisk/blender_export/' + name + '.png'
# 获取当前场景中的相机对象
camera = bpy.data.objects[name + ".001"]
# 获取对象的网格数据
back_mesh = bpy.data.objects["球体.001"]
ship = bpy.data.objects["Box5885.001"]
line = bpy.data.objects["Box5885.003"]# 链接数据库的句柄
db = sqlite3.connect(dbpath)
# cursor对象
db_cur = db.cursor()# 获取当前渲染设置
render_settings = bpy.context.scene.render
# 获取渲染图的尺寸
render_width = render_settings.resolution_x
render_height = render_settings.resolution_y
# 获取所有材质,用于获取材质颜色
materials = bpy.data.materialsmesh = back_mesh.data
# 获取模型的世界变换矩阵
world_mat = back_mesh.matrix_world
# 获取uv层,用于遍历获取uv数据
uv_layers_data = back_mesh.data.uv_layers.active.data
# 存储要写入数据库的数据
sql_value = []# 清空表格
def clearTable(tableName, cur):print('开始清空表'+tableName)sql = 'delete from ' + tableName + ' where 1 = 1'try:cur.execute(sql)print('清空表' + tableName + '成功')except Exception as e:print(e)print('清空表' + tableName + '失败')def dissconnectDB(cur):# 关闭游标cur.close()# 关闭连接db.close()print('断开数据库链接')# 执行sql创建表
def createTable(cur):print('开始创建表:pixelmap')# 执行sql创建表sql = 'create table pixelmap(id integer primary key,canvas integer not null,row0 float not null,col0 float not null,source  integer not null,row1 float not null,col1 float not null,wt float not null)'try:cur.execute(sql)print('创建表:pixelmap成功')except Exception as e:print(e)print('创建表:pixelmap失败')print('开始创建表:keyvalue')sql = 'create table keyvalue(id integer primary key,key string,value string)'try:cur.execute(sql)print('创建表:keyvalue成功')except Exception as e:print(e)print('创建表:keyvalue失败')def insertValueIntoTable(value, cur):print('开始插入数据到表pixelmap')try:# 执行sql创建表sql = 'insert into pixelmap(canvas,row0,col0,source,row1,col1,wt) values(?,?,?,?,?,?,?)'cur.executemany(sql, value)# 提交事务db.commit()print('插入成功')except Exception as e:print('插入失败')print(e)db.rollback()def insertValueIntoKeyValueTable(value, cur):print('开始插入数据到表keyvalue')try:# 执行sql创建表sql = 'insert into keyvalue(key,value) values(?,?)'cur.executemany(sql, value)# 提交事务db.commit()print('插入成功')except Exception as e:print('插入失败')print(e)db.rollback()def coord2_3d(camera, coord):out = mathutils.Vector(((2.0 * coord[0] / render_width) - 1.0,(2.0 * (1.0 - coord[1] / render_height)) - 1.0,-0.5))# 获取相机的投影矩阵perspective_matrix = camera.calc_matrix_camera(bpy.context.evaluated_depsgraph_get(),x = render_width,y = render_height)persinv = perspective_matrix.inverted()coord_world = camera.matrix_world @ (persinv @ out)return coord_worlddef obj_ray_cast(obj, coord, camera):view_vector = coord2_3d(camera, coord)ray_origin = camera.matrix_world.translationmatrix_inv = obj.matrix_world.copy().inverted()ray_origin_obj = matrix_inv @ ray_originray_target_obj = matrix_inv @ view_vectorray_direction_obj = ray_target_obj - ray_origin_obj# cast the raysuccess, location, normal, face_index = obj.ray_cast(ray_origin_obj, ray_direction_obj)if success:coord_world = back_mesh.matrix_world @ locationreturn (coord_world, face_index)else:return ((-1, -1), -1)# 计算三角形的面积
def triangle_area(v1, v2, v3):AB = v2 - v1AC = v3 - v1area = 0.5 * np.linalg.norm(np.cross(AB, AC))return areadef calculate_barycenter_3d(point, points):A = triangle_area(points[0], points[1], points[2])A1 = triangle_area(point, points[1], points[2])A2 = triangle_area(points[0], point, points[2])A3 = triangle_area(points[0], points[1], point)return (A1 / A, A2 / A, A3 / A, (A1 / A + A2 / A + A3 / A))def calculate_point_from_barycenter(barycenter, points):if len(barycenter) != 3 or len(points) != 3:return Nonex = barycenter[0] * points[0][0] + barycenter[1] * points[1][0] + barycenter[2] * points[2][0]y = barycenter[0] * points[0][1] + barycenter[1] * points[1][1] + barycenter[2] * points[2][1]return x, y# 计算点在三角形中的重心坐标，返回的坐标在值都是大于0的，则在三角形内部
def calculate_barycenter(point, points):if len(point) != 2:return (-1, 1, 0)if len(points) != 3:return (-1, 1, 0)x, y = point[0], point[1]p1, p2, p3 = points[0], points[1], points[2]denominator = (p2[1] - p3[1]) * (p1[0] - p3[0]) + (p3[0] - p2[0]) * (p1[1] - p3[1])if denominator == 0.0:return (-1, -1, -1)alpha = ((p2[1] - p3[1]) * (x - p3[0]) + (p3[0] - p2[0]) * (y - p3[1])) / denominatorbeta = ((p3[1] - p1[1]) * (x - p3[0]) + (p1[0] - p3[0]) * (y - p3[1])) / denominatorgamma = 1.0 - alpha - betareturn (alpha, beta, gamma)def rgba_to_hex(rgb):red = round(rgb[0] * 255)green = round(rgb[1] * 255)blue = round(rgb[2] * 255)hex_color = (red << 16) + (green << 8) + bluereturn hex(hex_color)# 获取材质的颜色(纯色材质)
def getMaterialColor(index):# 获取所有的材质materials = bpy.data.materialsmaterial = materials[index]# 如果材质包含 Principled BSDF Shader，则获取 Base Colorif material.use_nodes:nodes = material.node_tree.nodesprincipled_bsdf = nodes.get("Principled BSDF")if principled_bsdf is not None:base_color = principled_bsdf.inputs["Base Color"].default_valuereturn rgba_to_hex((base_color[0], base_color[1], base_color[2]))# print(f"Material Index: {index}, Base Color: {base_color[0],base_color[1],base_color[2],base_color[3]}")# 否则，尝试获取 Diffuse Shader 的颜色else:diffuse_shader = material.diffuse_colorreturn rgba_to_hex(diffuse_shader)def open_image(filepath):return Image.open(filepath)def get_pixel_color(image, x, y):# 获取指定位置的像素颜色值color = image.getpixel((x, y))red = color[0]green = color[1]blue = color[2]hex_color = (red << 16) + (green << 8) + bluereturn hex(hex_color)try:createTable(db_cur)clearTable('pixelmap',db_cur)clearTable('keyvalue',db_cur)# 渲染图像print("开始渲染图片")bpy.context.scene.render.filepath = export_image_path  # 输出路径bpy.context.scene.render.resolution_x = render_width  # 分辨率Xbpy.context.scene.render.resolution_y = render_height  # 分辨率Ybpy.ops.render.render(write_still=True)print("渲染图片结束")time.sleep(1)# 获取渲染图句柄print("获取渲染图句柄")image = open_image(export_image_path)for y in range(render_height):print("loading y...", y)for x in range(render_width):# 获取面的所有顶点对应的纹理坐标tex_coords = []# 获取面的所有顶点vertices = []coord = x, yship_coord, face_index_ship = obj_ray_cast(ship, coord, camera)# line_coord, face_index_line = obj_ray_cast(line, coord, camera)if ship_coord[0] != -1:sql_value.append((0, y, x, -1, 0.0, 0.0, get_pixel_color(image, x, y)))# elif line_coord[0] != -1:#     sql_value.append((0, y, x, -1, 0.0, 0.0, get_pixel_color(image, x, y)))else:coord_world, face_index = obj_ray_cast(back_mesh, coord, camera)if coord_world[0] != -1:face = mesh.polygons[face_index]loop_start = face.loop_startloop_end = face.loop_start + face.loop_totalif face.loop_total == 4:# blender中是使用四角面，也就是两个三角面合并后的面计算# 先获取到四个顶点vertices_0 = mesh.loops[face.loop_start].vertex_indexvertices_0_w = world_mat @ mesh.vertices[vertices_0].cotex_coords.append(uv_layers_data[face.loop_start].uv)vertices.append(vertices_0_w)vertices_1 = mesh.loops[face.loop_start+1].vertex_indexvertices_1_w = world_mat @ mesh.vertices[vertices_1].cotex_coords.append(uv_layers_data[face.loop_start+1].uv)vertices.append(vertices_1_w)vertices_2 = mesh.loops[face.loop_start+2].vertex_indexvertices_2_w = world_mat @ mesh.vertices[vertices_2].cotex_coords.append(uv_layers_data[face.loop_start+2].uv)vertices.append(vertices_2_w)# 计算重心坐标，判断该像素点是否在第一个三角面内barycenter = calculate_barycenter_3d(coord_world, vertices) if (barycenter[3] <= 1.000001):coord_xy = calculate_point_from_barycenter((barycenter[0], barycenter[1], barycenter[2]), tex_coords)sql_value.append((0, y, x, float(face.material_index), 1-coord_xy[1], coord_xy[0], 1.0))# 第二个三角面else:vertices_3 = mesh.loops[face.loop_start+3].vertex_indexvertices_3_w = world_mat @ mesh.vertices[vertices_3].cotex_coords[1] = uv_layers_data[face.loop_start+2].uvtex_coords[2] = uv_layers_data[face.loop_start+3].uvvertices[1] = vertices_2_wvertices[2] = vertices_3_w# 计算重心坐标，判断该像素点是否在第一个三角面内barycenter = calculate_barycenter_3d(coord_world, vertices)if (barycenter[3] <= 1.000001):coord_xy = calculate_point_from_barycenter((barycenter[0], barycenter[1], barycenter[2]), tex_coords)sql_value.append((0, y, x, float(face.material_index), 1-coord_xy[1], coord_xy[0], 1.0))else:vertices_0 = mesh.loops[face.loop_start].vertex_indextex_coords.append(uv_layers_data[face.loop_start].uv)vertices.append(world_mat @ mesh.vertices[vertices_0].co)vertices_1 = mesh.loops[face.loop_start+1].vertex_indextex_coords.append(uv_layers_data[face.loop_start+1].uv)vertices.append(world_mat @ mesh.vertices[vertices_1].co)vertices_2 = mesh.loops[face.loop_start+2].vertex_indextex_coords.append(uv_layers_data[face.loop_start+2].uv)vertices.append(world_mat @ mesh.vertices[vertices_2].co)# 计算重心坐标，判断该像素点是否在第一个三角面内barycenter = calculate_barycenter_3d(coord_world, vertices)if (barycenter[3] <= 1.000001):coord_xy = calculate_point_from_barycenter((barycenter[0], barycenter[1], barycenter[2]), tex_coords)sql_value.append((0, y, x, float(face.material_index), 1-coord_xy[1], coord_xy[0], 1.0))# sql_value.append((0,render_width-x,y, float(face.material_index), 1-coord_xy[1], coord_xy[0], 1.0))insertValueIntoTable(sql_value, db_cur)insertValueIntoKeyValueTable([("canvas_width",render_width),("canvas_height",render_height)],db_cur)dissconnectDB(db_cur)except Exception as e:dissconnectDB(db_cur)