How to render 3d object to silhouette image in python?

Question

I am trying to render an obj (a human body model) to its corresponding silhouette image given camera intrinsic&&extrinsic parameters and I want to know which renderer is suitable for the task. I don't want real time display of the rendered images because efficiency is my top concern. I have 100000 3d objects and i need to write a script to render the silhouette images of those objects in one go.

Answer 1

Here is a small example rendering with OpenGL to an image using ModernGL and Pillow

• pillow docs
• ModernGL docs

Sample code:

import struct

import ModernGL
from PIL import Image

ctx = ModernGL.create_standalone_context()

prog = ctx.program([
    ctx.vertex_shader('''
        #version 330
        in vec2 vert;
        void main() {
            gl_Position = vec4(vert, 0.0, 1.0);
        }
    '''),
    ctx.fragment_shader('''
        #version 330
        out vec4 color;
        void main() {
            color = vec4(0.3, 0.5, 1.0, 1.0);
        }
    '''),
])

vbo = ctx.buffer(struct.pack('6f', 0.0, 0.8, -0.6, -0.8, 0.6, -0.8))
vao = ctx.simple_vertex_array(prog, vbo, ['vert'])

fbo = ctx.framebuffer(ctx.renderbuffer((512, 512)))

fbo.use()
ctx.viewport = (0, 0, 512, 512)
ctx.clear(0.9, 0.9, 0.9)
vao.render()

pixels = fbo.read(components=3, alignment=1)
img = Image.frombytes('RGB', fbo.size, pixels).transpose(Image.FLIP_TOP_BOTTOM)
img.show()