import struct

import GLWindow
import ModernGL

# Window & Context

wnd = GLWindow.create_window()
ctx = ModernGL.create_context()

# Shaders & Program

prog = ctx.program([
    ctx.vertex_shader('''
        #version 330

        in vec2 vert;

        in vec4 vert_color;
        out vec4 frag_color;

        uniform vec2 scale;
        uniform float rotation;

        void main() {
            frag_color = vert_color;
            mat2 rot = mat2(
                cos(rotation), sin(rotation),
                -sin(rotation), cos(rotation)
            );
            gl_Position = vec4((rot * vert) * scale, 0.0, 1.0);
        }
    '''),
    ctx.fragment_shader('''
        #version 330

        in vec4 frag_color;
        out vec4 color;

        void main() {
            color = vec4(frag_color);
        }
    '''),
])

# Uniforms

scale = prog.uniforms['scale']
rotation = prog.uniforms['rotation']

width, height = wnd.size
scale.value = (height / width * 0.75, 0.75)

# Buffer

vbo = ctx.buffer(struct.pack(
    '18f',

    1.0, 0.0,
    1.0, 0.0, 0.0, 0.5,

    -0.5, 0.86,
    0.0, 1.0, 0.0, 0.5,

    -0.5, -0.86,
    0.0, 0.0, 1.0, 0.5,
))

# Put everything together

vao = ctx.simple_vertex_array(prog, vbo, ['vert', 'vert_color'])

# Main loop

while wnd.update():
    ctx.viewport = wnd.viewport
    ctx.clear(0.9, 0.9, 0.9)
    ctx.enable(ModernGL.BLEND)
    rotation.value = wnd.time
    vao.render(instances=10)

import struct

import GLWindow
import ModernGL

# Window & Context

wnd = GLWindow.create_window()
ctx = ModernGL.create_context()

# Shaders & Program

prog = ctx.program([
    ctx.vertex_shader('''
        #version 330

        in vec2 vert;

        in vec4 vert_color;
        out vec4 frag_color;

        uniform vec2 scale;
        uniform float rotation;

        void main() {
            frag_color = vert_color;
            float r = rotation * (0.5 + gl_InstanceID * 0.05);
            mat2 rot = mat2(cos(r), sin(r), -sin(r), cos(r));
            gl_Position = vec4((rot * vert) * scale, 0.0, 1.0);
        }
    '''),
    ctx.fragment_shader('''
        #version 330

        in vec4 frag_color;
        out vec4 color;

        void main() {
            color = vec4(frag_color);
        }
    '''),
])

# Uniforms

scale = prog.uniforms['scale']
rotation = prog.uniforms['rotation']

width, height = wnd.size
scale.value = (height / width * 0.75, 0.75)

# Buffer

vbo = ctx.buffer(struct.pack(
    '18f',

    1.0, 0.0,
    1.0, 0.0, 0.0, 0.5,

    -0.5, 0.86,
    0.0, 1.0, 0.0, 0.5,

    -0.5, -0.86,
    0.0, 0.0, 1.0, 0.5,
))

# Put everything together

vao = ctx.simple_vertex_array(prog, vbo, ['vert', 'vert_color'])

# Main loop

while wnd.update():
    ctx.viewport = wnd.viewport
    ctx.clear(0.9, 0.9, 0.9)
    ctx.enable(ModernGL.BLEND)
    rotation.value = wnd.time
    vao.render(instances=10)

fix blending example