moderngl_colored_triangle_framebuffer_render_to_image.py

1import moderngl
2import numpy as np
3from PIL import Image
4
5# Create a context in standalone mode
6ctx = moderngl.create_standalone_context()
7
8# Define the vertex shader and fragment shader
9prog = ctx.program(
10    vertex_shader='''
11        #version 330
12        in vec2 in_vert;
13        in vec3 in_color;
14        out vec3 v_color;
15        void main() {
16            v_color = in_color;
17            gl_Position = vec4(in_vert, 0.0, 1.0);
18        }
19    ''',
20    fragment_shader='''
21        #version 330
22        in vec3 v_color;
23        out vec4 f_color;
24        void main() {
25            f_color = vec4(v_color, 1.0);
26        }
27    ''',
28)
29
30# Define the vertices of a triangle and their colors
31vertices = np.array([
32    # x, y, r, g, b
33    0.0, 0.8, 1.0, 0.0, 0.0,
34    -0.6, -0.8, 0.0, 1.0, 0.0,
35    0.6, -0.8, 0.0, 0.0, 1.0,
36], dtype='f4')
37
38# Create a Vertex Buffer Object (VBO) and a Vertex Array Object (VAO)
39vbo = ctx.buffer(vertices)
40vao = ctx.simple_vertex_array(prog, vbo, 'in_vert', 'in_color')
41
42# Create a Framebuffer Object (FBO) to render into
43fbo = ctx.framebuffer(color_attachments=[ctx.texture((512, 512), 4)])
44fbo.use()
45fbo.clear(0.0, 0.0, 0.0, 1.0)
46
47# Render the triangle
48vao.render(moderngl.TRIANGLES)
49
50# Read the pixels from the framebuffer and save as an image
51data = fbo.read(components=4)
52image = Image.frombytes('RGBA', (512, 512), data).transpose(Image.FLIP_TOP_BOTTOM)
53image.show()