/*
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* Copyright (C) 2021 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "gl/shader-object.hpp"
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#include <glad/glad.h>
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#include <stdexcept>
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namespace gl {
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static constexpr GLenum gl_shader_type_lut[] =
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{
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GL_VERTEX_SHADER,
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GL_FRAGMENT_SHADER,
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GL_GEOMETRY_SHADER
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};
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shader_object::shader_object(shader_stage stage):
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gl_shader_id(0),
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stage(stage),
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compiled(false)
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{
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// Look up OpenGL shader type enumeration that corresponds to the given stage
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GLenum gl_shader_type = gl_shader_type_lut[static_cast<std::size_t>(stage)];
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// Create an OpenGL shader object
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gl_shader_id = glCreateShader(gl_shader_type);
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// Handle OpenGL errors
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if (!gl_shader_id)
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{
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throw std::runtime_error("An error occurred while creating an OpenGL shader object.");
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}
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}
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shader_object::~shader_object()
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{
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// Flags the OpenGL shader object for deletion
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glDeleteShader(gl_shader_id);
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}
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void shader_object::source(const char* buffer, std::size_t size)
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{
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// Replace OpenGL shader object source code
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GLint gl_length = size;
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glShaderSource(gl_shader_id, 1, &buffer, &gl_length);
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// Handle OpenGL errors
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switch (glGetError())
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{
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case GL_INVALID_VALUE:
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throw std::runtime_error("Shader object handle is not a value generated by OpenGL.");
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break;
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case GL_INVALID_OPERATION:
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throw std::runtime_error("Shader object handle is not a shader object.");
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break;
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}
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}
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bool shader_object::compile()
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{
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// Compile OpenGL shader object
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glCompileShader(gl_shader_id);
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// Handle OpenGL errors
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switch (glGetError())
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{
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case GL_INVALID_VALUE:
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throw std::runtime_error("Shader object handle is not a value generated by OpenGL.");
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break;
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case GL_INVALID_OPERATION:
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throw std::runtime_error("Shader object handle is not a shader object.");
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break;
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}
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// Get OpenGL shader object compilation status
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GLint gl_compile_status;
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glGetShaderiv(gl_shader_id, GL_COMPILE_STATUS, &gl_compile_status);
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compiled = (gl_compile_status == GL_TRUE);
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// Get OpenGL shader object info log length
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GLint gl_info_log_length;
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glGetShaderiv(gl_shader_id, GL_INFO_LOG_LENGTH, &gl_info_log_length);
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if (gl_info_log_length > 0)
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{
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// Resize string to accommodate OpenGL shader object info log
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info_log.resize(gl_info_log_length);
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// Read OpenGL shader object info log into string
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glGetShaderInfoLog(gl_shader_id, gl_info_log_length, &gl_info_log_length, info_log.data());
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// Remove redundant null terminator from string
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info_log.pop_back();
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}
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else
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{
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// Empty info log
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info_log.clear();
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}
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// Return compilation status
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return compiled;
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}
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} // namespace gl
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