nuuro 0.1.5

A specialized 2D game library
Documentation 
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// Copyright 2020-2020 Juan Villacorta
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::os::raw::{c_char, c_void};
use std::{mem, ptr, str};

use gl;
use gl::types::*;

use super::shader_util;
use crate::renderer::shaders;

pub struct SpriteProgram {
    pub handle: GLuint,
    pub vao: GLuint,
    vs: GLuint,
    fs: GLuint,
    pub uniform_tex: GLint,
    pub uniform_inv_tex_dims: GLint,
}

impl SpriteProgram {
    pub fn new() -> SpriteProgram {
        let vs = shader_util::compile_shader(shaders::VS_SPRITE_SRC, gl::VERTEX_SHADER);
        let fs = shader_util::compile_shader(shaders::FS_SPRITE_SRC, gl::FRAGMENT_SHADER);
        let handle = shader_util::link_program(vs, fs);
        let vao = SpriteProgram::make_vao(handle);
        unsafe {
            SpriteProgram {
                handle,
                vao,
                vs,
                fs,
                uniform_tex: gl::GetUniformLocation(handle, c_str!("tex")),
                uniform_inv_tex_dims: gl::GetUniformLocation(handle, c_str!("inv_tex_dims")),
            }
        }
    }

    fn make_vao(program_handle: GLuint) -> GLuint {
        let mut vao = 0;
        unsafe {
            let attrib_vert = gl::GetAttribLocation(program_handle, c_str!("vert"));
            let attrib_vs_inv_tex_sample_dims =
                gl::GetAttribLocation(program_handle, c_str!("vs_inv_tex_sample_dims"));
            let attrib_vs_tex_vert_rb =
                gl::GetAttribLocation(program_handle, c_str!("vs_tex_vert_rb"));
            let attrib_vs_flash_ratio =
                gl::GetAttribLocation(program_handle, c_str!("vs_flash_ratio"));

            gl::GenVertexArrays(1, &mut vao);
            gl::BindVertexArray(vao);

            // TODO be consistent with the gl::TRUE/FALSE values in gl::VertexAttribPointer...

            gl::EnableVertexAttribArray(attrib_vert as GLuint);
            gl::VertexAttribPointer(
                attrib_vert as GLuint,
                2,
                gl::FLOAT,
                gl::FALSE,
                7 * mem::size_of::<GLfloat>() as i32,
                ptr::null(),
            );

            gl::EnableVertexAttribArray(attrib_vs_inv_tex_sample_dims as GLuint);
            gl::VertexAttribPointer(
                attrib_vs_inv_tex_sample_dims as GLuint,
                2,
                gl::FLOAT,
                gl::TRUE,
                7 * mem::size_of::<GLfloat>() as i32,
                (2 * mem::size_of::<GLfloat>()) as *const c_void,
            );

            gl::EnableVertexAttribArray(attrib_vs_tex_vert_rb as GLuint);
            gl::VertexAttribPointer(
                attrib_vs_tex_vert_rb as GLuint,
                2,
                gl::FLOAT,
                gl::TRUE,
                7 * mem::size_of::<GLfloat>() as i32,
                (4 * mem::size_of::<GLfloat>()) as *const c_void,
            );

            gl::EnableVertexAttribArray(attrib_vs_flash_ratio as GLuint);
            gl::VertexAttribPointer(
                attrib_vs_flash_ratio as GLuint,
                1,
                gl::FLOAT,
                gl::TRUE,
                7 * mem::size_of::<GLfloat>() as i32,
                (6 * mem::size_of::<GLfloat>()) as *const c_void,
            );

            gl::BindVertexArray(0);
        }
        vao
    }
}

impl Drop for SpriteProgram {
    fn drop(&mut self) {
        unsafe {
            gl::DeleteProgram(self.handle);
            gl::DeleteShader(self.fs);
            gl::DeleteShader(self.vs);
            gl::DeleteVertexArrays(1, &self.vao);
        }
    }
}