glutils.py

"""
Copyright (c) 2023, UrocyonF
All rights reserved.

This source code is licensed under the BSD-style license found in the
LICENSE file in the root directory of this source tree. 

Author: UrocyonF
Date: 2022 - 2023
"""
#!/usr/bin/env python3

from PIL import Image
import OpenGL.GL as GL
import os


def compile_shader(shader_content, shader_type):
    shader_id = GL.glCreateShader(shader_type)
    GL.glShaderSource(shader_id, shader_content)
    GL.glCompileShader(shader_id)
    success = GL.glGetShaderiv(shader_id, GL.GL_COMPILE_STATUS)
    if not success:
        log = GL.glGetShaderInfoLog(shader_id).decode('ascii')
        print(f'{25*"-"}\nError compiling shader: \n\
            {shader_content}\n{5*"-"}\n{log}\n{25*"-"}')
    return shader_id


def create_program( vertex_source, fragment_source):
    vs_id = compile_shader(vertex_source, GL.GL_VERTEX_SHADER)
    fs_id = compile_shader(fragment_source, GL.GL_FRAGMENT_SHADER)
    if vs_id and fs_id:
        program_id = GL.glCreateProgram()
        GL.glAttachShader(program_id, vs_id)
        GL.glAttachShader(program_id, fs_id)
        GL.glLinkProgram(program_id)
        success = GL.glGetProgramiv(program_id, GL.GL_LINK_STATUS)
        if not success:
            log = GL.glGetProgramInfoLog(program_id).decode('ascii')
            print(f'{25*"-"}\nError linking program:\n{log}\n{25*"-"}')
        GL.glDeleteShader(vs_id)
        GL.glDeleteShader(fs_id)
    return program_id


def create_program_from_file(vs_file, fs_file):
    vs_content = open(vs_file, 'r').read() if os.path.exists(vs_file)\
        else print(f'{25*"-"}\nError reading file:\n{vs_file}\n{25*"-"}')
    fs_content = open(fs_file, 'r').read() if os.path.exists(fs_file)\
        else print(f'{25*"-"}\nError reading file:\n{fs_file}\n{25*"-"}')
    return create_program(vs_content, fs_content)


def load_texture(filename):
    if not os.path.exists(filename):
        print(f'{25*"-"}\nError reading file:\n{filename}\n{25*"-"}')
    im = Image.open(filename).transpose(Image.FLIP_TOP_BOTTOM).convert('RGBA')
    texture_id = GL.glGenTextures(1)
    GL.glBindTexture(GL.GL_TEXTURE_2D, texture_id)
    GL.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_WRAP_S, GL.GL_REPEAT)
    GL.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_WRAP_T, GL.GL_REPEAT)
    GL.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MAG_FILTER, GL.GL_LINEAR)
    GL.glTexParameteri(GL.GL_TEXTURE_2D, GL.GL_TEXTURE_MIN_FILTER, GL.GL_LINEAR)
    GL.glTexImage2D(GL.GL_TEXTURE_2D, 0, GL.GL_RGBA, im.width, im.height, 0, GL.GL_RGBA, GL.GL_UNSIGNED_BYTE, im.tobytes())
    return texture_id