shader_code.cxx

#include <cgv/base/base.h>
#include "shader_code.h"
#include <cgv/base/register.h>
#include <cgv/base/import.h>
#include <cgv/utils/advanced_scan.h>
#include <cgv/utils/tokenizer.h>
#include <cgv/ppp/ph_processor.h>
#include <cgv/utils/dir.h>
#include <cgv/utils/file.h>
#include <cgv/type/variant.h>
 
#ifdef WIN32
#pragma warning(disable:4996)
#endif
 
using namespace cgv::base;
using namespace cgv::type;
using namespace cgv::utils;
 
namespace cgv {
    namespace render {
 
std::map<std::string, std::string> shader_code::code_cache;
 
std::map<std::string, std::string> shader_code::shader_file_name_map;
 
bool shader_code::shader_file_name_map_initialized = false;
 
shader_config::shader_config()
{
    trace_file_names = false;
    show_file_paths = false;
}
 
std::string shader_config::get_type_name() const
{
    return "shader_config";
}
 
bool shader_config::self_reflect(cgv::reflect::reflection_handler& rh)
{
    return 
        rh.reflect_member("shader_path", shader_path) &&
        rh.reflect_member("show_file_paths", show_file_paths);
}
 
shader_config_ptr get_shader_config()
{
    static shader_config_ptr config;
    if (!config) {
        config = shader_config_ptr(new shader_config); 
        if (getenv("CGV_SHADER_PATH"))
            config->shader_path = getenv("CGV_SHADER_PATH");
        else if (getenv("CGV_DIR"))
            config->shader_path = 
                std::string(getenv("CGV_DIR"))+"/libs/cgv_gl/glsl;"+
                std::string(getenv("CGV_DIR"))+"/libs/plot/glsl;"+
                std::string(getenv("CGV_DIR")) + "/libs/cgv_app/glsl;" +
                std::string(getenv("CGV_DIR")) + "/libs/cgv_g2d/glsl;" +
                std::string(getenv("CGV_DIR")) + "/libs/cgv_gpgpu/glsl;" +
                std::string(getenv("CGV_DIR")) + "/libs/holo_disp;" +
                std::string(getenv("CGV_DIR")) + "/plugins/examples";
    }
    return config;
}
 
void shader_code::decode_if_base64(std::string& content) {
//#ifdef _WIN32
    if (!content.empty()) {
        // test if the first character is equal to the base64 prefix (ANSI 'paragraph' char with hexcode A7)
        if(content[0] == char(0xA7))
            content = decode_base64(content.substr(1));
    }
/*#else
    if (content.size() > 1) {
        if ((uint8_t&)content[0]==0xC2 && (uint8_t&)content[1]==0xA7) // UTF-8 for '�'
            content = decode_base64(content.substr(2));
        else if (
            content.size() > 2 &&
            (int)content[0] == -17 &&
            (int)content[1] == -65 &&
            (int)content[2] == -67) {
            content = decode_base64(content.substr(3));
        }
    }
#endif*/
}
 
std::string shader_code::get_last_error(const std::string& file_name, const std::string& last_error)
{
    std::string fn = shader_code::find_file(file_name);
    std::vector<line> lines;
    split_to_lines(last_error, lines);
    std::string formated_error;
    for (unsigned int i = 0; i<lines.size(); ++i) {
        std::string l = to_string((const token&)(lines[i]));
        if (to_upper(l.substr(0, 5)) == "ERROR") {
            std::vector<token> toks;
            tokenizer(l).set_sep(":").set_ws("").bite_all(toks);
            formated_error += fn + "(";
            if (toks.size() > 4) {
                formated_error += to_string(toks[4])+") : error G0001: ";
                if (toks.size() > 6)
                    formated_error += l.substr(toks[6].begin-&l[0]);
            }
            else {
                formated_error += "1) : error G0000: ";
                if (toks.size() > 2)
                    formated_error += l.substr(toks[2].begin-&l[0]);
            }
            formated_error += "\n";
        }
        else {
            std::vector<token> toks;
            tokenizer(l).set_sep(":()").set_ws("").bite_all(toks);
            unsigned int i, j, k; int n;
            for (i=0; i<toks.size(); ++i) {
                if (to_string(toks[i]) == "(")
                    break;
            }
            for (j=0; j<toks.size(); ++j) {
                if (to_string(toks[j]) == ")")
                    break;
            }
            for (k=0; k<toks.size(); ++k) {
                if (to_string(toks[k]) == ":")
                    break;
            }
            if (k < toks.size() && i < j && j < k && is_integer(toks[i].end, toks[j].begin, n)) {
                std::string _fn = fn;
                int shader_id;
                if (i > 0 && is_integer(toks[i-1].begin, toks[i-1].end, shader_id)) {
                    if (shader_id >= 1000) {
                        unsigned si = shader_id-1000;
                        if (si < get_shader_config()->inserted_shader_file_names.size())
                            _fn = get_shader_config()->inserted_shader_file_names[si];
                    }
                    else {
                        if ((unsigned)shader_id < get_shader_config()->shader_file_names.size())
                            _fn = get_shader_config()->shader_file_names[shader_id];
                    }
                }
                formated_error += _fn + l.substr(toks[i].begin - &l[0])+"\n";
            }
            else
                formated_error += l+"\n";
        }
    }
    return formated_error;
}
 
shader_code::shader_code()
{
    st = ST_DETECT;
}
shader_code::~shader_code()
{
    if (ctx_ptr && ctx_ptr->make_current())
        destruct(*ctx_ptr);
    else
        if (handle)
            std::cerr << "shader code not destructed correctly" << std::endl;
}
 
void shader_code::destruct(const context& ctx)
{
    if (!handle)
        return;
    ctx.shader_code_destruct(*this);
    handle = 0;
}
 
std::string shader_code::find_file(const std::string& file_name, bool search_exhaustive)
{
    if (file_name.substr(0, 6) == "str://" || file_name.substr(0, 6) == "res://") {
        std::map<std::string, resource_file_info>::const_iterator it = ref_resource_file_map().find(file_name.substr(6));
        if (it != ref_resource_file_map().end())
            return file_name;
        else
            return "";
    }
    if (file::exists(file_name))
        return file_name;
    
    std::string try_name = file::get_path(ref_prog_name()) + "/" + file_name;
    if (file::exists(try_name))
        return try_name;
 
    std::map<std::string, resource_file_info>::const_iterator it = 
        ref_resource_file_map().find(file_name);
    if (it != ref_resource_file_map().end()) {
        if (it->second.file_offset == -1)
            return std::string("str://") + file_name;
        else
            return std::string("res://") + file_name;
    }
    if (get_shader_config()->shader_path.empty()) {
        try_name = std::string("glsl/") + file_name;
        if (file::exists(try_name))
            return try_name;
        try_name = file::get_path(ref_prog_name()) + "/glsl/" + file_name;
        if (file::exists(try_name))
            return try_name;
        return "";
    }
 
    if(!shader_file_name_map_initialized) {
        std::string path_list = get_shader_config()->shader_path;
 
        size_t pos = 0;
        do {
            size_t end_pos = path_list.find_first_of(';', pos);
            std::string path;
            if(end_pos == std::string::npos) {
                path = path_list.substr(pos);
                pos = path_list.length();
            } else {
                path = path_list.substr(pos, end_pos - pos);
                pos = end_pos + 1;
            }
            
            std::vector<std::string> file_names;
            dir::glob(path, file_names, "*gl*", true);
 
            for(const auto& file_name : file_names) {
                std::string ext = file::get_extension(file_name);
                if(ext.length() > 2) {
                    if(ext[0] == 'g' && ext[1] == 'l' ||
                       ext[0] == 'p' && ext[1] == 'g' && ext[2] == 'l')
                        shader_file_name_map.emplace(file::get_file_name(file_name), file_name);
                }
            }
        } while(pos < path_list.length());
 
        shader_file_name_map_initialized = true;
    }
 
    std::map<std::string, std::string>::const_iterator file_name_map_it = shader_file_name_map.find(file_name);
    if(file_name_map_it != shader_file_name_map.end()) {
        try_name = file_name_map_it->second;
        if(file::exists(try_name))
           return try_name;
    } else if(!search_exhaustive) {
        return "";
    }
 
    return file::find_in_paths(file_name, get_shader_config()->shader_path, true);
}
 
std::string shader_code::retrieve_code(const std::string& file_name, bool use_cache, std::string* _last_error) {
 
    std::string source = "";
 
    if(use_cache) {
        auto it = code_cache.find(file_name);
        if(it != code_cache.end()) {
            source = it->second;
        }
    } else {
        code_cache.clear();
    }
 
    if(source.empty())
        source = read_code_file(file_name, _last_error);
 
    if(use_cache)
        code_cache.emplace(file_name, source);
 
    return source;
}
 
ShaderType shader_code::detect_shader_type(const std::string& file_name)
{
    std::string ext = to_lower(file::get_extension(file_name));
    ShaderType st = ST_VERTEX;
    if (ext == "glfs" || ext == "pglfs")
        st = ST_FRAGMENT;
    else if (ext == "glgs" || ext == "pglgs")
        st = ST_GEOMETRY;
    else if (ext == "glcs" || ext == "pglcs")
        st = ST_COMPUTE;
    else if (ext == "gltc" || ext == "pgltc")
        st = ST_TESS_CONTROL;
    else if (ext == "glte" || ext == "pglte")
        st = ST_TESS_EVALUATION;
    return st;
}
 
std::string shader_code::resolve_includes(const std::string& source, bool use_cache, std::set<std::string>& included_file_names, std::string* _last_error)
{
    const std::string identifier = "#include ";
 
    std::string resolved_source = "";
 
    std::vector<line> lines;
    split_to_lines(source, lines);
 
    for(size_t i = 0; i < lines.size(); ++i) {
        std::string current_line = to_string(lines[i]);
 
        // search for the include identifier
        size_t identifier_pos = current_line.find(identifier);
        if(identifier_pos != std::string::npos) {
            // remove identifier and all content before; an include directive must be the first and only statement on a line
            current_line.erase(0, identifier_pos + identifier.length());
            
            // trim whitespace
            trim(current_line);
 
            if(current_line.length() > 0) {
                // remove quotation marks, leaving only the include path
                std::string include_file_name = current_line.substr(1, current_line.length() - 2);
                std::string include_source = retrieve_code(include_file_name, use_cache, _last_error);
 
                // check whether this file was already included and skip if this is the case
                if(included_file_names.find(include_file_name) == included_file_names.end()) {
                    included_file_names.insert(include_file_name);
                    current_line = resolve_includes(include_source, use_cache, included_file_names, _last_error);
                } else {
                    current_line = "";
                }
            }
 
            // skip this line if nothing needs to be included (removes the include statement from the code)
            if(current_line == "")
                continue;
        }
 
        resolved_source += current_line + '\n';
    }
 
    return resolved_source;
}
 
std::string shader_code::resolve_includes(const std::string& source, bool use_cache, std::string* _last_error) {
    std::set<std::string> included_file_names;
    return resolve_includes(source, use_cache, included_file_names, _last_error);
}
 
void shader_code::resolve_version_and_extensions(std::string& source) {
    struct index_range {
        size_t begin = 0;
        size_t end = 0;
 
        bool empty() const {
            return begin >= end;
        }
 
        size_t length() const {
            return end - begin;
        }
    };
 
    struct preprocessor_directive_t {
        enum Type {
            kUndefined,
            kVersion,
            kExtension
        };
 
        Type type = kUndefined;
        index_range type_range;
        index_range content_range;
        // TODO: Replace with semantics for replace comment //! and conditional expansion //?
        bool is_special_comment = false;
    };
 
    static const std::map<std::string, preprocessor_directive_t::Type> identifier_to_type = {
        { "#version", preprocessor_directive_t::Type::kVersion },
        { "#extension", preprocessor_directive_t::Type::kExtension },
    };
 
    enum class CommentType {
        kNone,
        kLine,
        kBlock,
        kSpecial
    };
 
    std::vector<preprocessor_directive_t> directives;
 
    // read source string and collect all known directives in source
    size_t i = 0;
    
    CommentType comment = CommentType::kNone;
    while(i < source.length()) {
        char c = source[i];
 
        switch(c) {
        case '#':
            if(comment == CommentType::kNone || comment == CommentType::kSpecial) {
                // search for the next non-escaped newline which is not preceded by a backslash
                size_t end = i;
                do {
                    end = source.find('\n', end + 1);
                } while(end != std::string::npos && source[end - 1] == '\\');
 
                if(end == std::string::npos)
                    end = source.length();
 
                // There must be at least one space that separates the directive type and its value/content between indices i and end.
                // A valid directive also must have a value/content.
 
                // TODO: support space between # and directive type
 
                size_t space = source.find(' ', i + 1);
                if(space < end) {
                    index_range type_range = { i, space };
                    std::string type_string = source.substr(type_range.begin, type_range.length());
                    auto it = identifier_to_type.find(type_string);
                    if(it != identifier_to_type.end()) {
                        preprocessor_directive_t directive;
                        directive.type = it->second;
                        directive.type_range = { i, space };
                        directive.content_range = { space + 1, end };
                        directive.is_special_comment = comment == CommentType::kSpecial;
                        directives.push_back(directive);
                    }
                }
                comment = CommentType::kNone;
                i = end;
            }
            break;
        case '/':
            if(comment == CommentType::kNone && (i + 1) < source.length()) {
                if(source[i + 1] == '/')
                    comment = CommentType::kLine;
                else if(source[i + 1] == '*')
                    comment = CommentType::kBlock;
                ++i;
            }
            break;
        case '*':
            if(comment == CommentType::kBlock && (i + 1) < source.length()) {
                if(source[i + 1] == '/')
                    comment = CommentType::kNone;
                ++i;
            }
            break;
        case '!':
        case '?':
            if(comment == CommentType::kLine)
                comment = CommentType::kSpecial;
            break;
        case '\n':
            if(comment != CommentType::kBlock)
                comment = CommentType::kNone;
            break;
        default:
            break;
        }
 
        ++i;
    }
 
    struct version_t {
        size_t number = 0;
        bool has_profile = false;
        bool is_core_profile = false;
    };
 
    // find the highest version number and profile
    version_t highest_version;
    for(const preprocessor_directive_t& directive : directives) {
        if(directive.type != preprocessor_directive_t::Type::kVersion)
            continue;
 
        std::string content = cgv::utils::trim(source.substr(directive.content_range.begin, directive.content_range.length()));
 
        std::vector<cgv::utils::token> tokens;
        cgv::utils::split_to_tokens(content, tokens, "", true, "", "", " \t");
 
        version_t version;
 
        if(!tokens.empty()) {
            if(!cgv::utils::from_string(version.number, to_string(tokens[0])))
                version.number = 0;
        }
 
        if(tokens.size() > 1) {
            std::string profile = to_string(tokens[1]);
            if(profile == "core") {
                version.has_profile = true;
                version.is_core_profile = true;
            } else if(profile == "compatibility") {
                version.has_profile = true;
                version.is_core_profile = false;
            }
        }
 
        if(version.number > highest_version.number)
            highest_version.number = version.number;
 
        if(version.has_profile) {
            if(highest_version.has_profile) {
                if(version.is_core_profile)
                    highest_version.is_core_profile = true;
            } else {
                highest_version.has_profile = true;
                highest_version.is_core_profile = version.is_core_profile;
            }
        }
    }
 
    // disable all non-commented version and extension directives by changing them to comments
    for(const preprocessor_directive_t& directive : directives) {
        if(!directive.is_special_comment && (directive.type == preprocessor_directive_t::Type::kVersion || directive.type == preprocessor_directive_t::Type::kExtension)) {
            // Prevent expensive insertion operatons by simply overwriting the first two characters of the directive, since it is no longer needed anyway.
            // This also has the advantage that the indices stay valid.
            source[directive.type_range.begin] = '/';
            source[directive.type_range.begin + 1] = '/';
        }
    }
 
    // build a new header for the shader by first adding the version directive using the highest version
    std::string header = "#version " + std::to_string(highest_version.number);
    if(highest_version.has_profile) {
        header += " ";
        header += highest_version.is_core_profile ? "core" : "compatibility";
    }
    header += "\n";
 
    // next add all extensions directly after the version to comply with the specification of some newer shader versions
    for(const preprocessor_directive_t& directive : directives) {
        if(directive.type == preprocessor_directive_t::Type::kExtension)
            header += "#extension " + source.substr(directive.content_range.begin, directive.content_range.length()) + "\n";
    }
    header += '\n';
 
    source.insert(0, header);
}
 
ShaderType shader_code::get_shader_type() const
{
    return st;
}
 
std::string shader_code::read_code_file(const std::string &file_name, std::string* last_error)
{
    std::string source;
    std::string fn = find_file(file_name);
    if (fn.empty()) {
        if (last_error) {
            *last_error = "could not find shader file ";
            *last_error += file_name;
        }
        return "";
    }
    if (!cgv::base::read_data_file(fn, source, true)) {
        if (last_error) {
            *last_error = "could not read shader file ";
            *last_error += fn;
        }
        return "";
    }
    if (get_shader_config()->show_file_paths)
        std::cout << "read shader code <" << fn << ">" << std::endl;
 
    decode_if_base64(source);
 
    if (file::get_extension(file_name)[0] == 'p') {
        std::string code;
        get_shader_config()->inserted_shader_file_names.clear();
        std::string paths = file::get_path(fn);
        if (!get_shader_config()->shader_path.empty())
            paths = paths+";"+get_shader_config()->shader_path;
 
        cgv::ppp::ph_processor php(paths, true);
        php.configure_insert_to_shader(&get_shader_config()->inserted_shader_file_names);
        if (!php.parse_string(source))
            return "";
        if (!php.process_to_string(code))
            return "";
        cgv::ppp::clear_variables();
        source = code;
    }
    return source;
}
 
bool shader_code::read_code(const context& ctx, const std::string &file_name, ShaderType st, const shader_compile_options& options)
{
    if (st == ST_DETECT)
        st = detect_shader_type(file_name);
 
    // get source code from cache or read file
    std::string source = retrieve_code(file_name, ctx.is_shader_file_cache_enabled(), &last_error);
 
    source = resolve_includes(source, ctx.is_shader_file_cache_enabled());
    
    resolve_version_and_extensions(source);
 
    set_defines_and_snippets(source, options);
 
    if (st == ST_VERTEX && ctx.get_gpu_vendor_id() == GPUVendorID::GPU_VENDOR_AMD)
        set_vertex_attrib_locations(source);
 
    if (source.empty())
        return false;
 
    return set_code(ctx, source, st);
}
 
bool shader_code::set_code(const context& ctx, const std::string &source, ShaderType _st)
{
    st = _st;
    destruct(ctx);
    ctx_ptr = &ctx;
    return ctx.shader_code_create(*this, st, source);
}
 
void shader_code::set_defines_and_snippets(std::string& source, const shader_compile_options& options)
{
    enum class DirectiveType {
        kUndefined,
        kDefine,
        kSnippet
    };
 
    struct directive_t {
        DirectiveType type = DirectiveType::kUndefined;
        std::string identifier;
        std::string value;
    };
    
    if(options.defines.empty() && options.snippets.empty())
        return;
 
    std::map<std::string, directive_t*> directives;
    std::map<size_t, directive_t*> directives_per_line;
    size_t version_line_index = std::numeric_limits<size_t>::max();
 
    std::vector<cgv::utils::line> lines;
    split_to_lines(source, lines);
    for(size_t i = 0; i < lines.size(); ++i) {
        const cgv::utils::line& line = lines[i];
 
        if(line.empty())
            continue;
 
        DirectiveType directive_type = DirectiveType::kUndefined;
 
        // Pre-processor directives and snippet markers must appear on separate lines. Only whitespace characters are allowed to appear before them.
        const char* ptr = line.begin;
        for(; ptr < line.end; ++ptr) {
            char c = *ptr;
 
            if(c == '#') {
                directive_type = DirectiveType::kDefine;
                break;
            } else if(c == '/') {
                if(line.end - ptr > 7) {
                    if(cgv::utils::token(ptr, ptr + 8) == "//$cgv::") {
                        directive_type = DirectiveType::kSnippet;
                        break;
                    }
                }
            }
 
            if(!is_space(c))
                break;
        }
 
        if(directive_type != DirectiveType::kUndefined) {
            std::vector<cgv::utils::token> tokens;
            split_to_tokens(cgv::utils::token(ptr, line.end), tokens, "");
 
            directive_t* directive = nullptr;
 
            switch(directive_type) {
            case DirectiveType::kDefine:
                // A valid define directive will have at least two tokens (directive and name)
                if(tokens.size() > 1) {
                    std::string first_token_str = to_string(tokens.front());
 
                    if(first_token_str == "#version") {
                        version_line_index = i;
                    } else if(first_token_str == "#define" && !tokens[1].empty()) {
                        directive = new directive_t{ directive_type };
                        directive->identifier = to_string(tokens[1]);
 
                        // Any following tokens are considered to be the value of the define.
                        if(tokens.size() > 2) {
                            cgv::utils::token value_token(tokens[2].begin, tokens.back().end);
                            directive->value = to_string(value_token);
                        }
                    }
                }
                break;
            case DirectiveType::kSnippet:
                // A valid snippet directive will have one token (identifier).
                if(tokens.size() == 1) {
                    tokens.front().begin += 3;
                    if(!tokens.front().empty())
                        directive = new directive_t{ directive_type, to_string(tokens.front()), "" };
                }
                break;
            default:
                break;
            }
 
            if(directive) {
                directives[directive->identifier] = directive;
                directives_per_line[i] = directive;
            }
        }
    }
 
    std::vector<std::pair<std::string, std::string>> additional_defines;
 
    for(const auto& define : options.defines) {
        auto it = directives.find(define.first);
        if(it != directives.end() && it->second->type == DirectiveType::kDefine)
            it->second->value = define.second;
        else
            additional_defines.push_back(define);
    }
 
    bool use_snippets = false;
    if(!options.snippets.empty()) {
        additional_defines.push_back({ "CGV_USE_SNIPPETS", "" });
        use_snippets = true;
    }
 
    std::string out;
    // The output string is going to have a similar length as the input.
    out.reserve(source.length());
 
    for(size_t i = 0; i < lines.size(); ++i) {
        const cgv::utils::line& line = lines[i];
 
        auto it = directives_per_line.find(i);
        if(it != directives_per_line.end()) {
            const directive_t* directive = it->second;
 
            switch(directive->type) {
            case DirectiveType::kDefine:
                out += "#define " + directive->identifier + " " + directive->value;
                break;
            case DirectiveType::kSnippet:
                if(use_snippets) {
                    auto it = std::find_if(options.snippets.begin(), options.snippets.end(), [directive](const shader_code_snippet& snippet) {
                        return directive->identifier == "cgv::" + snippet.id;
                    });
                    if(it != options.snippets.end())
                        out += it->content;
                    else
                        out += to_string(line);
                }
                break;
            default:
                break;
            }
        } else {
            out += to_string(line);
        }
 
        out += '\n';
 
        // Put additional defines after version directive.
        if(version_line_index == i) {
            out += '\n';
            for(const auto& define : additional_defines)
                out += "#define " + define.first + " " + define.second + '\n';
        }
    }
 
    for(const auto& pair : directives)
        delete pair.second;
 
    directives.clear();
    directives_per_line.clear();
 
    source = std::move(out);
}
 
void shader_code::set_vertex_attrib_locations(std::string& source)
{
    struct vertex_attribute {
        token tok;
        int location = -1;
        std::string type = "";
        std::string name = "";
 
        vertex_attribute(const token& tok) : tok(tok) {}
 
        std::string to_string() {
            std::string str = "layout (location = ";
            str += std::to_string(location);
            str += ") in ";
            str += type + " ";
            str += name + ";";
            return str;
        }
    };
 
    std::vector<token> parts;
    std::vector<token> tokens;
    std::vector<vertex_attribute> attribs;
    std::vector<bool> attrib_flags;
    size_t version_idx = 0;
    int version_number = 0;
    bool is_core = false;
    bool no_upgrade = false;
 
    source = strip_cpp_comments(source);
 
    split_to_tokens(source, parts, "", true, "", "", ";\n");
 
    attrib_flags.resize(parts.size(), false);
 
    size_t part_idx = 0;
 
    // First read the version. The only thing allowed before the version statement is comments and empty lines.
    // Both get removed bevore splitting the source into parts, so the first part must be the version.
    split_to_tokens(parts[part_idx], tokens, "", true, "", "", " \t");
 
    if(tokens.size() > 1 && tokens[0] == "#version") {
        version_idx = part_idx;
 
        std::string number_str = to_string(tokens[1]);
        char* p_end;
        const long num = std::strtol(number_str.c_str(), &p_end, 10);
        if(number_str.c_str() != p_end)
            version_number = static_cast<int>(num);
 
        if(tokens.size() == 3 && tokens[2] == "core")
            is_core = true;
    }
 
    ++part_idx;
 
    // Search for the optional NO_UPGRADE define, which must come directly after the version statement.
    tokens.clear();
    split_to_tokens(parts[part_idx], tokens, "", true, "", "", " \t");
 
    if(tokens.size() > 1 && tokens[0] == "#define") {
        if(tokens[1] == "NO_UPGRADE") {
            no_upgrade = true;
            ++part_idx;
        }
    }
 
    // return if the shader should not be upgraded
    if(no_upgrade)
        return;
 
    // now get all vertex attributes
    for(; part_idx < parts.size(); ++part_idx) {
        auto& tok = parts[part_idx];
 
        while(tok.begin < tok.end && is_space(*tok.begin))
            ++tok.begin;
 
        if(tok.size() > 2) {
            int parentheses_count = 0;
            bool is_new_word = true;
            bool was_new_word = true;
 
            for(unsigned i = 0; i < tok.size() - 2; ++i) {
                char c = tok[i];
 
                if(c == '(')
                    ++parentheses_count;
 
                if(c == ')')
                    --parentheses_count;
 
                is_new_word = is_space(c) || c == ')';
 
                if(c == 'i' && tok[i + 1] == 'n' && tok[i + 2] == ' ') {
                    if(was_new_word && parentheses_count == 0) {
                        attribs.push_back(vertex_attribute(tok));
                        attrib_flags[part_idx] = true;
                        break;
                    }
                }
 
                was_new_word = is_new_word;
            }
        }
    }
 
    // return if no vertex attributes were found
    if(attribs.size() == 0)
        return;
 
    int max_location = -1;
    for(size_t i = 0; i < attribs.size(); ++i) {
        auto& attrib = attribs[i];
 
        tokens.clear();
        split_to_tokens(attrib.tok, tokens, "", true, "", "", " \t()");
 
        size_t size = tokens.size();
 
        if(tokens.size() > 2) {
            // last two entries must be type and name
            attrib.type = to_string(tokens[size - 2]);
            attrib.name = to_string(tokens[size - 1]);
 
            // find location if present
            size_t equals_idx = -1;
            for(size_t j = 0; j < size; ++j) {
                auto& tok = tokens[j];
                if(tok.size() == 1 && tok[0] == '=')
                    equals_idx = j;
            }
 
            if(equals_idx != -1 && equals_idx > 0 && equals_idx < size - 1) {
                if(to_string(tokens[equals_idx - 1]) == "location") {
                    std::string val_str = to_string(tokens[equals_idx + 1]);
                    char* p_end;
                    const long num = std::strtol(val_str.c_str(), &p_end, 10);
                    if(val_str.c_str() != p_end) {
                        attrib.location = static_cast<int>(num);
                        max_location = std::max(max_location, attrib.location);
                    }
                }
            }
        }
    }
 
    for(size_t i = 0; i < attribs.size(); ++i) {
        auto& attrib = attribs[i];
        if(attrib.location < 0)
            attrib.location = ++max_location;
    }
 
    size_t attrib_idx = 0;
    size_t accumulate_offset = 0;
    size_t content_offset = reinterpret_cast<size_t>(source.data());
 
    for(size_t i = 0; i < parts.size(); ++i) {
        auto& tok = parts[i];
 
        if(i == version_idx || attrib_flags[i]) {
            size_t token_begin = reinterpret_cast<size_t>(tok.begin);
            size_t token_end = reinterpret_cast<size_t>(tok.end);
 
            size_t offset = token_begin - content_offset;
            size_t length = token_end - token_begin;
 
            std::string str = "";
 
            if(attrib_flags[i]) {
                auto& attrib = attribs[attrib_idx];
                ++attrib_idx;
                str = attrib.to_string() + "\n";
            } else {
                version_number = std::max(version_number, 330);
                str = "#version " + std::to_string(version_number) + (is_core ? " core" : "");
            }
 
            offset += accumulate_offset;
            accumulate_offset += str.length() - length - 1;
 
            std::string first_part = source.substr(0, offset);
            std::string second_part = source.substr(offset + length + 1);
 
            source = first_part + str + second_part;
        }
    }
}
 
bool shader_code::compile(const context& ctx)
{
    if (!ctx.shader_code_compile(*this)) {
        user_data = 0;
        return false;
    }
    int id = 1;
    user_data = (void*&) id;
    return true;
}
 
bool shader_code::read_and_compile(const context& ctx, const std::string &file_name, ShaderType st, const shader_compile_options& options, bool show_error)
{
    if (!read_code(ctx, file_name, st, options))
        return false;
 
    if (!compile(ctx)) {
        if (show_error)
            std::cerr << get_last_error(file_name, last_error).c_str() << std::endl;
        return false;
    }
 
    return true;
}
 
bool shader_code::is_compiled() const
{
    return user_data != 0;
}
 
 
    }
}
 
struct shader_config_registration
{
    shader_config_registration()
    {
        register_object(cgv::render::get_shader_config(), "register global shader config");
    }
};
 
shader_config_registration shader_config_registration_instance;