test_vao_bind_offset.py

import struct
import unittest

import moderngl

_static = {
    'context': None
}


def get_context() -> moderngl.Context:
    ctx = _static.get('context')

    if ctx is None:
        ctx = moderngl.create_standalone_context(size=(100, 100))
        _static['context'] = ctx

    return ctx


class VertexArrayBindTest(unittest.TestCase):

    @classmethod
    def setUpClass(cls):
        cls.ctx = get_context()

    def test_vec4(self):
        prog = self.ctx.program(
            vertex_shader='''
                #version 400
                in vec4 in_vert;
                out vec4 out_vert;
                void main() {
                    out_vert = in_vert;
                }
            ''',
            varyings=['out_vert']
        )
        vbo1 = self.ctx.buffer(struct.pack('8f', 0, 1, 2, 3, 4, 5, 6, 7))
        vbo2 = self.ctx.buffer(reserve=16)
        vao = self.ctx.vertex_array(prog, [(vbo1, '4f', 'in_vert')])
        # No offset.
        vao.transform(vbo2, moderngl.POINTS, vertices=1)
        self.assertTupleEqual(struct.unpack('4f', vbo2.read()),
                              (0., 1., 2., 3.),
                              'Copy vec4 failed.')
        # Zero offset.
        in_location = prog['in_vert'].location
        vao.bind(in_location, 'f', vbo1, '4f', offset=0)
        vao.transform(vbo2, moderngl.POINTS, vertices=1)
        self.assertTupleEqual(struct.unpack('4f', vbo2.read()),
                              (0., 1., 2., 3.),
                              'Copy vec4 failed with vao.bind, offset=0.')
        # Skip first 4 numbers.
        vao.bind(in_location, 'f', vbo1, '4f', offset=16)
        vao.transform(vbo2, moderngl.POINTS, vertices=1)
        self.assertTupleEqual(struct.unpack('4f', vbo2.read()),
                              (4., 5., 6., 7.),
                              'Copy vec4 failed with vao.bind, offset=16.')

    def test_mat2(self):
        prog = self.ctx.program(
            vertex_shader='''
                #version 400
                in mat2 in_vert;
                out mat2 out_vert;
                void main() {
                    out_vert = in_vert;
                }
            ''',
            varyings=['out_vert']
        )
        vbo1 = self.ctx.buffer(struct.pack('8f', 0, 1, 2, 3, 4, 5, 6, 7))
        vbo2 = self.ctx.buffer(reserve=16)
        vao = self.ctx.vertex_array(prog, [(vbo1, '4f', 'in_vert')])
        # No offset.
        vao.transform(vbo2, moderngl.POINTS, vertices=1)
        self.assertTupleEqual(struct.unpack('4f', vbo2.read()),
                              (0., 1., 2., 3.),
                              'Copy mat2 failed.')
        # Zero offset.
        in_location = prog['in_vert'].location
        vao.bind(in_location, 'f', vbo1, '4f', offset=0)
        vao.transform(vbo2, moderngl.POINTS, vertices=1)
        self.assertTupleEqual(struct.unpack('4f', vbo2.read()),
                              (0., 1., 2., 3.),
                              'Copy mat2 failed with vao.bind, offset = 0.')
        # Skip first 4 numbers.
        vao.bind(in_location, 'f', vbo1, '4f', offset=16)
        vao.transform(vbo2, moderngl.POINTS, vertices=1)
        self.assertTupleEqual(struct.unpack('4f', vbo2.read()),
                              (4., 5., 6., 7.),
                              'Copy mat2 failed with vao.bind, offset = 16.')


if __name__ == '__main__':
    unittest.main()