io_mesh_uv_layout/export_uv_png.py

   1 # SPDX-License-Identifier: GPL-2.0-or-later
   2
   3 import bpy
   4 import gpu
   5 from mathutils import Vector, Matrix
   6 from mathutils.geometry import tessellate_polygon
   7 from gpu_extras.batch import batch_for_shader
   8
   9
  10 def export(filepath, face_data, colors, width, height, opacity):
  11     offscreen = gpu.types.GPUOffScreen(width, height)
  12     offscreen.bind()
  13
  14     try:
  15         fb = gpu.state.active_framebuffer_get()
  16         fb.clear(color=(0.0, 0.0, 0.0, 0.0))
  17         draw_image(face_data, opacity)
  18
  19         pixel_data = fb.read_color(0, 0, width, height, 4, 0, 'UBYTE')
  20         pixel_data.dimensions = width * height * 4
  21         save_pixels(filepath, pixel_data, width, height)
  22     finally:
  23         offscreen.unbind()
  24         offscreen.free()
  25
  26
  27 def draw_image(face_data, opacity):
  28     gpu.state.blend_set('ALPHA')
  29
  30     with gpu.matrix.push_pop():
  31         gpu.matrix.load_matrix(get_normalize_uvs_matrix())
  32         gpu.matrix.load_projection_matrix(Matrix.Identity(4))
  33
  34         draw_background_colors(face_data, opacity)
  35         draw_lines(face_data)
  36
  37     gpu.state.blend_set('NONE')
  38
  39
  40 def get_normalize_uvs_matrix():
  41     '''matrix maps x and y coordinates from [0, 1] to [-1, 1]'''
  42     matrix = Matrix.Identity(4)
  43     matrix.col[3][0] = -1
  44     matrix.col[3][1] = -1
  45     matrix[0][0] = 2
  46     matrix[1][1] = 2
  47     return matrix
  48
  49
  50 def draw_background_colors(face_data, opacity):
  51     coords = [uv for uvs, _ in face_data for uv in uvs]
  52     colors = [(*color, opacity) for uvs, color in face_data for _ in range(len(uvs))]
  53
  54     indices = []
  55     offset = 0
  56     for uvs, _ in face_data:
  57         triangles = tessellate_uvs(uvs)
  58         indices.extend([index + offset for index in triangle] for triangle in triangles)
  59         offset += len(uvs)
  60
  61     shader = gpu.shader.from_builtin('2D_FLAT_COLOR')
  62     batch = batch_for_shader(
  63         shader, 'TRIS',
  64         {"pos": coords, "color": colors},
  65         indices=indices,
  66     )
  67     batch.draw(shader)
  68
  69
  70 def tessellate_uvs(uvs):
  71     return tessellate_polygon([uvs])
  72
  73
  74 def draw_lines(face_data):
  75     coords = []
  76     for uvs, _ in face_data:
  77         for i in range(len(uvs)):
  78             start = uvs[i]
  79             end = uvs[(i + 1) % len(uvs)]
  80             coords.append((start[0], start[1]))
  81             coords.append((end[0], end[1]))
  82
  83     shader = gpu.shader.from_builtin('POLYLINE_UNIFORM_COLOR')
  84     shader.uniform_float("viewportSize", gpu.state.viewport_get()[2:])
  85     shader.uniform_float("lineWidth", 1.0)
  86     shader.uniform_float("color", (0.0, 0.0, 0.0, 1.0))
  87
  88     batch = batch_for_shader(shader, 'LINES', {"pos": coords})
  89     batch.draw(shader)
  90
  91
  92 def save_pixels(filepath, pixel_data, width, height):
  93     image = bpy.data.images.new("temp", width, height, alpha=True)
  94     image.filepath = filepath
  95     image.pixels = [v / 255 for v in pixel_data]
  96     image.save()
  97     bpy.data.images.remove(image)