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#include "TableDefinition.h"
#include "parser/DefTokeniser.h"
#include <cmath>
namespace shaders
{
TableDefinition::TableDefinition(const std::string& name) :
DeclarationBase<ITableDefinition>(decl::Type::Table, name),
_snap(false),
_clamp(false)
{}
float TableDefinition::getValue(float index)
{
ensureParsed();
// Don't bother if we don't have any values to look up
if (_values.empty())
{
return 0.0f;
}
auto numValues = _values.size();
if (numValues == 1)
{
return _values[0];
}
if (_clamp)
{
if (index > 1.0f)
{
return _values[numValues - 1];
}
else if (index < 0.0f)
{
return _values[0];
}
// Map the index to the [0..N-1] interval
index *= numValues - 1;
}
else
{
// Only take the fractional part of the index
index = std::fmod(index, 1.0f);
// Mirror negative indices to the positive range (catch negative -0.0f)
if (index < 0 && index != 0.0f)
{
index += 1.0f;
}
// Map the index to the [0..N) interval
index *= numValues;
}
auto leftIdx = static_cast<std::size_t>(std::floor(index)) % numValues;
if (_snap)
{
// If snap is active, just use the left-bound index
return _values[leftIdx];
}
// No snapping, pick the next value to the right to interpolate
auto rightIdx = (leftIdx + 1) % numValues;
float fraction = index - leftIdx;
return (1-fraction)*_values[leftIdx] + fraction*_values[rightIdx];
}
void TableDefinition::onBeginParsing()
{
_snap = false;
_clamp = false;
_values.clear();
}
void TableDefinition::parseFromTokens(parser::DefTokeniser& tokeniser)
{
std::size_t level = 0;
while (tokeniser.hasMoreTokens())
{
std::string token = tokeniser.nextToken();
if (token == "{")
{
if (++level > 1)
{
throw parser::ParseException("Too many opening braces.");
}
}
else if (token == "}")
{
if (level == 0)
{
throw parser::ParseException("Too many closing braces.");
}
--level;
}
else if (token == "clamp")
{
if (level != 0)
{
throw parser::ParseException("The 'clamp' keyword cannot be used at this scope/position.");
}
_clamp = true;
}
else if (token == "snap")
{
if (level != 0)
{
throw parser::ParseException("The 'snap' keyword cannot be used at this scope/position.");
}
_snap = true;
}
else
{
// Expect a numeric value at this point
try
{
_values.push_back(std::stof(token));
}
catch (std::invalid_argument& ex)
{
throw parser::ParseException("Invalid token '" + token + "' encountered: " + ex.what());
}
}
}
}
} // namespace
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