linux-wallpaperengine-kde/BasicShaderLoader.cpp

#include <irrlicht/irrlicht.h>
#include <iostream>
#include <fstream>
#include <string>
#include "BasicShaderLoader.h"
#include "nier_test.h"
#include "common.h"

BasicShaderLoader::BasicShaderLoader (irr::io::path file, Type type, bool recursive = false)
{
    // begin with an space so it gets ignored properly on parse
    if (recursive == false)
    {
        this->m_content =	"#version 120\n"
                             "#define texSample2D texture2D\n"
                             "#define frac fract\n";
    }
    else
    {
        this->m_content = "";
    }

    std::ifstream _in (file.c_str ());
    this->m_content.append (std::istreambuf_iterator<char> (_in), std::istreambuf_iterator<char> ());
    this->m_type = type;
}

bool BasicShaderLoader::peekString(std::string str, std::string::const_iterator& it)
{
    std::string::const_iterator check = str.begin();
    std::string::const_iterator cur = it;

    while (cur != this->m_content.end () && check != str.end ())
    {
        if (*cur != *check) return false;

        cur ++; check ++;
    }

    if (cur == this->m_content.end ())
    {
        return false;
    }

    if (check != str.end ())
    {
        return false;
    }

    it = cur;

    return true;
}

bool BasicShaderLoader::expectSemicolon (std::string::const_iterator& it)
{
    if (*it != ';')
    {
        this->m_error = true;
        this->m_errorInfo = "Expected semicolon but got " + *it;
        return false;
    }

    it ++;

    return true;
}

void BasicShaderLoader::ignoreSpaces(std::string::const_iterator &it)
{
    while (it != this->m_content.end() && (*it == ' ' || *it == '\t')) it ++;
}

void BasicShaderLoader::ignoreUpToNextLineFeed (std::string::const_iterator& it)
{
    while (it != this->m_content.end() && *it != '\n') it ++;
}

void BasicShaderLoader::ignoreUpToBlockCommentEnd (std::string::const_iterator& it)
{
    while (it != this->m_content.end() && this->peekString ("*/", it) == false) it ++;
}

std::string BasicShaderLoader::extractType (std::string::const_iterator& it)
{
    std::vector<std::string>::const_iterator cur = sTypes.begin ();
    std::vector<std::string>::const_iterator end = sTypes.end ();

    while (cur != end)
    {
        if (this->peekString (*cur, it) == true)
        {
            return *cur;
        }

        cur ++;
    }

    this->m_error = true;
    this->m_errorInfo = "Expected type";
    return "";
}

std::string BasicShaderLoader::extractName (std::string::const_iterator& it)
{
    std::string::const_iterator cur = it;
    std::string::const_iterator begin = cur;

    // first character has to be a valid alphabetic characer
    if (this->isChar (cur) == false && *cur != '_')
    {
        this->m_error = true;
        this->m_errorInfo = "Expected name doesn't start with a valid character";
        return "";
    }

    cur ++;

    while (cur != this->m_content.end () && (this->isChar (cur) == true || *cur == '_' || this->isNumeric (cur) == true)) cur ++;

    it = cur;

    return std::string (begin, cur);
}

bool BasicShaderLoader::isChar (std::string::const_iterator& it)
{
    return ((*it) >= 'A' && (*it) <= 'Z') || ((*it) >= 'a' && (*it) <= 'z');
}

bool BasicShaderLoader::isNumeric (std::string::const_iterator& it)
{
    return (*it) >= '0' && (*it) <= '9';
}

std::string BasicShaderLoader::extractQuotedValue(std::string::const_iterator& it)
{
    std::string::const_iterator cur = it;

    if (*cur != '"')
    {
        m_error = true;
        m_errorInfo = "Expected opening \" but got " + (*cur);
        return "";
    }

    cur ++;

    while (cur != this->m_content.end () && *cur != '\n' && *cur != '"') cur ++;

    if (cur == this->m_content.end ())
    {
        m_error = true;
        m_errorInfo = "Expected closing \" not found";
        it = cur;
        return "";
    }

    std::string filename = std::string (++it, cur);

    it = ++cur;

    return filename;
}

std::string BasicShaderLoader::lookupShaderFile (std::string filename)
{
    irr::io::path shaderTest = _example_base_folder; shaderTest += "/"; shaderTest += filename.c_str ();
    irr::io::IFileSystem *fs = device->getFileSystem ();

    // by default try to load from current folder
    // we might want, in the future, to load things from different folders
    // to provide standard functionality
    if (fs->existFile (shaderTest) == false)
    {
        this->m_error = true;
        this->m_errorInfo = "Cannot find file " + filename + " to include";
        return "";
    }

    // now compile the new shader
    // do not include the default header (as it's already included in the parent)
    BasicShaderLoader loader (shaderTest, this->m_type, true);

    return *loader.precompile ();
}

std::string BasicShaderLoader::lookupReplaceSymbol (std::string symbol)
{
    std::map<std::string, std::string>::const_iterator cur = sVariableReplacement.begin ();
    std::map<std::string, std::string>::const_iterator end = sVariableReplacement.end ();

    while (cur != end)
    {
        if (cur->first == symbol)
        {
            return cur->second;
        }

        cur ++;
    }

    // if there is no replacement, return the original
    return symbol;
}

std::string* BasicShaderLoader::precompile ()
{
#define BREAK_IF_ERROR if (this->m_error == true) { device->getLogger ()->log ("ERROR COMPILING SHADER"); device->getLogger ()->log (this->m_errorInfo.c_str ()); return nullptr; }
    // parse the shader and find #includes and such things and translate them to the correct name
    // also remove any #version definition to prevent errors
    std::string::const_iterator it = this->m_content.begin ();

    // reset error indicator
    this->m_error = false;
    this->m_errorInfo = "";

    // search preprocessor macros and parse them
    while (it != this->m_content.end () && this->m_error == false)
    {
        // TODO: on precompilation steps search for attributes and replace them
        // TODO: with the correct opengl shader variable
        if (*it == ' ' || *it == '\t' || *it == '\n' || *it == '\r' || *it == '\0' || *it == '{' || *it == '}' || *it == '[' || *it == ']' || *it == '.')
        {
            this->m_compiledContent += *it;
            it ++;
        }
        else if (*it == '#')
        {
            if (this->peekString ("#include", it) == true)
            {
                std::string filename = "";

                // ignore whitespaces
                this->ignoreSpaces (it); BREAK_IF_ERROR
                // extract value between quotes
                filename = this->extractQuotedValue (it); BREAK_IF_ERROR

                // try to find the file first
                this->m_compiledContent += "// begin of included from file " + filename + "\r\n";
                this->m_compiledContent += this->lookupShaderFile (filename);
                this->m_compiledContent += "\r\n// end of included from file " + filename + "\r\n";
            }
            else
            {
                this->m_compiledContent += '#';
                it ++;
            }
        }
        else if (*it == 'a')
        {
            // find attribute definitions
            if (this->peekString ("attribute", it) == true)
            {
                this->ignoreSpaces (it);
                std::string type = this->extractType (it); BREAK_IF_ERROR
                this->ignoreSpaces (it);
                std::string name = this->extractName (it); BREAK_IF_ERROR
                this->ignoreSpaces (it);
                this->expectSemicolon (it); BREAK_IF_ERROR

                this->m_compiledContent += "// attribute";
                this->m_compiledContent += " " + type + " ";
                this->m_compiledContent += name;
                this->m_compiledContent += "; /* replaced by " + this->lookupReplaceSymbol (name) + " */";
            }
            else
            {
                // check for types first
                std::string type = this->extractType (it);

                // types not found, try names
                if (this->m_error == false)
                {
                    this->m_compiledContent += type;
                }
                else
                {
                    this->m_error = false;
                    std::string name = this->extractName (it);

                    if (this->m_error == false)
                    {
                        // check if the name is a translated one or not
                        this->m_compiledContent += this->lookupReplaceSymbol (name);
                    }
                    else
                    {
                        this->m_error = false;
                        this->m_compiledContent += *it;
                        it ++;
                    }
                }
            }
        }
        else if (*it == '/')
        {
            if (this->peekString ("//", it) == true)
            {
                std::string::const_iterator begin = it - 2;
                this->ignoreUpToNextLineFeed (it);
                this->m_compiledContent.append (begin, it);
                device->getLogger ()->log (*it + "asdf");
            }
            else if (this->peekString ("/*", it) == true)
            {
                std::string::const_iterator begin = it - 2;
                this->ignoreUpToBlockCommentEnd (it);
                this->m_compiledContent.append (begin, it);
            }
            else
            {
                this->m_compiledContent += *it;
                it ++;
            }
        }
        else
        {
            // check for types first
            std::string type = this->extractType (it);

            // types not found, try names
            if (this->m_error == false)
            {
                this->m_compiledContent += type;
            }
            else
            {
                this->m_error = false;
                std::string name = this->extractName (it);

                if (this->m_error == false)
                {
                    // check if the name is a translated one or not
                    this->m_compiledContent += this->lookupReplaceSymbol (name);
                }
                else
                {
                    this->m_error = false;
                    this->m_compiledContent += *it;
                    it ++;
                }
            }
        }
    }

    device->getLogger ()->log ("Compiled shader output");
    device->getLogger ()->log (this->m_compiledContent.c_str ());

    return &this->m_compiledContent;
#undef BREAK_IF_ERROR
}

static std::map<std::string, std::string>  BasicShaderLoader::sVariableReplacement =
{
    {"a_Position", "gl_Vertex"},
    {"a_TexCoord", "gl_MultiTexCoord0"},
};

static std::vector<std::string> BasicShaderLoader::sTypes =
{
    "vec4", "vec3", "vec2", "float"
};