/*
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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-template.hpp"
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#include <algorithm>
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#include <sstream>
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namespace gl {
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shader_template::shader_template(const std::string& source_code)
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{
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source(source_code);
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}
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shader_template::shader_template()
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{}
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void shader_template::source(const std::string& source)
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{
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// Reset template
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template_source.clear();
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vertex_directives.clear();
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fragment_directives.clear();
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geometry_directives.clear();
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define_directives.clear();
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// Iterate through source line-by-line
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std::istringstream source_stream(source);
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std::string line;
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while (std::getline(source_stream, line))
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{
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std::string token;
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std::istringstream line_stream(line);
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// Detect `#pragma` directives
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if (line_stream >> token && token == "#pragma")
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{
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if (line_stream >> token)
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{
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// Map line numbers of supported directives
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if (token == "define")
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{
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if (line_stream >> token)
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define_directives.insert({token, template_source.size()});
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}
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else if (token == "vertex")
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vertex_directives.insert(template_source.size());
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else if (token == "fragment")
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fragment_directives.insert(template_source.size());
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else if (token == "geometry")
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geometry_directives.insert(template_source.size());
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}
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}
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// Append line to template source
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template_source.push_back(line);
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}
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}
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std::string shader_template::configure(gl::shader_stage stage, const dictionary_type& definitions) const
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{
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replace_stage_directives(stage);
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replace_define_directives(definitions);
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// Join vector of source lines into single string
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std::ostringstream stream;
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std::copy(template_source.begin(), template_source.end(), std::ostream_iterator<std::string>(stream, "\n"));
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return stream.str();
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}
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gl::shader_object* shader_template::compile(gl::shader_stage stage, const dictionary_type& definitions) const
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{
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// Generate shader object source
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std::string object_source = configure(stage, definitions);
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// Create new shader object
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gl::shader_object* object = new gl::shader_object(stage);
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// Set shader object source
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object->source(object_source.c_str(), object_source.length());
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// Compile shader object
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object->compile();
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return object;
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}
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gl::shader_program* shader_template::build(const dictionary_type& definitions) const
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{
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gl::shader_object* vertex_object = nullptr;
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gl::shader_object* fragment_object = nullptr;
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gl::shader_object* geometry_object = nullptr;
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// Create shader program
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gl::shader_program* program = new gl::shader_program();
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if (has_vertex_directive())
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{
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// Compile vertex shader object and attach to shader program
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vertex_object = compile(gl::shader_stage::vertex, definitions);
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program->attach(vertex_object);
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}
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if (has_fragment_directive())
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{
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// Compile fragment shader object and attach to shader program
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fragment_object = compile(gl::shader_stage::fragment, definitions);
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program->attach(fragment_object);
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}
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if (has_geometry_directive())
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{
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// Compile fragment shader object and attach to shader program
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geometry_object = compile(gl::shader_stage::geometry, definitions);
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program->attach(geometry_object);
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}
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// Link attached shader objects into shader program
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program->link();
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if (vertex_object)
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{
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// Detach and delete vertex shader object
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program->detach(vertex_object);
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delete vertex_object;
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}
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if (fragment_object)
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{
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// Detach and delete fragment shader object
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program->detach(fragment_object);
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delete fragment_object;
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}
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if (geometry_object)
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{
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// Detach and delete geometry shader object
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program->detach(geometry_object);
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delete geometry_object;
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}
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return program;
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}
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void shader_template::replace_stage_directives(gl::shader_stage stage) const
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{
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// Determine stage directives according to the shader stage being generated
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const std::string vertex_directive = (stage == gl::shader_stage::vertex) ? "#define __VERTEX__" : "/* #undef __VERTEX__ */";
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const std::string fragment_directive = (stage == gl::shader_stage::fragment) ? "#define __FRAGMENT__" : "/* #undef __FRAGMENT__ */";
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const std::string geometry_directive = (stage == gl::shader_stage::geometry) ? "#define __GEOMETRY__" : "/* #undef __GEOMETRY__ */";
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// Handle `#pragma <stage>` directives
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for (std::size_t i: vertex_directives)
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template_source[i] = vertex_directive;
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for (std::size_t i: fragment_directives)
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template_source[i] = fragment_directive;
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for (std::size_t i: geometry_directives)
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template_source[i] = geometry_directive;
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}
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void shader_template::replace_define_directives(const dictionary_type& definitions) const
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{
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// For each `#pragma define <key>` directive
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for (const auto& define_directive: define_directives)
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{
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// Get a reference to the directive line
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std::string& line = template_source[define_directive.second];
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// Check if the corresponding definition was given by the configuration
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auto definitions_it = definitions.find(define_directive.first);
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if (definitions_it != definitions.end())
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{
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// Definition found, Replace `#pragma define <key>` with `#define <key>` or `#define <key> <value>`
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line = "#define " + define_directive.first;
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if (!definitions_it->second.empty())
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line += " " + definitions_it->second;
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}
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else
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{
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// Definition not found, replace `#pragma define <key>` with the comment `/* #undef <key> */`.
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line = "/* #undef " + define_directive.first + " */";
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}
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}
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}
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bool shader_template::has_vertex_directive() const
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{
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return !vertex_directives.empty();
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}
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bool shader_template::has_fragment_directive() const
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{
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return !fragment_directives.empty();
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}
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bool shader_template::has_geometry_directive() const
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{
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return !geometry_directives.empty();
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}
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bool shader_template::has_define_directive(const std::string& name) const
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{
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return (define_directives.find(name) != define_directives.end());
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}
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} // namespace gl
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