ShaderStage.h

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//
// Copyright Contributors to the MaterialX Project
// SPDX-License-Identifier: Apache-2.0
//

#ifndef MATERIALX_SHADERSTAGE_H
#define MATERIALX_SHADERSTAGE_H

/// @file
/// Class related to holding information for shader stages

#include <MaterialXGenShader/Export.h>

#include <MaterialXGenShader/GenOptions.h>
#include <MaterialXGenShader/ShaderGraph.h>
#include <MaterialXGenShader/Syntax.h>

#include <MaterialXFormat/File.h>

#include <MaterialXCore/Node.h>

#include <sstream>

// Restrict a scoped block of statements to a specific shader stage, as
// is required for multi-stage shading languages.  Statements within
// the block will only be emitted when processing the given stage.
#define DEFINE_SHADER_STAGE(stage, name) if (stage.getName() == name)

// These macros are deprecated, and should be replaced with DEFINE_SHADER_STAGE.
#define BEGIN_SHADER_STAGE(stage, name) \
    if (stage.getName() == name)        \
    {
#define END_SHADER_STAGE(stage, name) }

MATERIALX_NAMESPACE_BEGIN

namespace Stage
{

/// Identifier for pixel stage.
/// This is the main stage used by all shader targets.
/// For single stage shader targets this is the one
/// and only stage.
/// Shader targets with multiple stages can add additional
/// stage identifiers to the Stage namespace.
extern MX_GENSHADER_API const string PIXEL;

} // namespace Stage

class VariableBlock;
/// Shared pointer to a VariableBlock
using VariableBlockPtr = std::shared_ptr<VariableBlock>;
/// Shared pointer to a map between string identifiers and VariableBlocks
using VariableBlockMap = std::unordered_map<string, VariableBlockPtr>;
/// A standard function predicate taking an ShaderPort pointer and returning a boolean.
using ShaderPortPredicate = std::function<bool(ShaderPort*)>;

/// @class VariableBlock
/// A block of variables in a shader stage
class MX_GENSHADER_API VariableBlock
{
  public:
    VariableBlock(const string& name, const string& instance) :
        _name(name),
        _instance(instance)
    {
    }

    /// Get the name of this block.
    const string& getName() const { return _name; }

    /// Set the name of this block.
    void setName(const string& name) { _name = name; }

    /// Get the instance name of this block.
    const string& getInstance() const { return _instance; }

    /// Set the instance name of this block.
    void setInstance(const string& instance) { _instance = instance; }

    /// Return true if the block has no variables.
    bool empty() const { return _variableOrder.empty(); }

    /// Return the number of variables in this block.
    size_t size() const { return _variableOrder.size(); }

    /// Return a variable by index.
    ShaderPort* operator[](size_t index) { return _variableOrder[index]; }

    /// Return a variable by index.
    const ShaderPort* operator[](size_t index) const { return _variableOrder[index]; }

    /// Return a const reference to our variable order vector.
    const vector<ShaderPort*>& getVariableOrder() const { return _variableOrder; }

    /// Return a variable by name. Throws exception if
    /// no variable is found by the given name.
    ShaderPort* operator[](const string& name);

    /// Return a variable by name. Throws exception if
    /// no variable is found by the given name.
    const ShaderPort* operator[](const string& name) const;

    /// Return a variable by name. Returns nullptr if
    /// no variable is found by the given name.
    ShaderPort* find(const string& name);

    /// Return a variable by name. Returns nullptr if
    /// no variable is found by the given name.
    const ShaderPort* find(const string& name) const;

    /// Find a port based on a predicate
    ShaderPort* find(const ShaderPortPredicate& predicate);

    /// Add a new shader port to this block.
    /// @param type The desired shader port type
    /// @param name The shader port name
    /// @param value The value to attach to the shader port
    /// @param shouldWiden When false, an exception is thrown if the type of the existing port with
    ///   the same name does not match the requested type. When true, the types can mismatch, and the
    ///   type of any existing port is widened to match the requested type when necessary.
    /// @return A new shader port, or a pre-existing shader port with the same name.
    ShaderPort* add(const TypeDesc* type, const string& name, ValuePtr value = nullptr, bool shouldWiden = false);

    /// Add an existing shader port to this block.
    void add(ShaderPortPtr port);

  private:
    string _name;
    string _instance;
    std::unordered_map<string, ShaderPortPtr> _variableMap;
    vector<ShaderPort*> _variableOrder;
};

/// @class ShaderStage
/// A shader stage, containing the state and
/// resulting source code for the stage.
class MX_GENSHADER_API ShaderStage
{
  public:
    using FunctionCallId = std::pair<const ShaderNode*, int>;
    struct Scope
    {
        Syntax::Punctuation punctuation;
        std::set<FunctionCallId> functions;
        Scope(Syntax::Punctuation p) :
            punctuation(p) { }
    };

  public:
    /// Contructor.
    ShaderStage(const string& name, ConstSyntaxPtr syntax);

    /// Return the stage name.
    const string& getName() const { return _name; }

    /// Return the stage function name.
    const string& getFunctionName() const { return _functionName; }

    /// Set the stage source code.
    void setSourceCode(const string& code) { _code = code; }

    /// Return the stage source code.
    const string& getSourceCode() const { return _code; }

    /// Create a new uniform variable block.
    VariableBlockPtr createUniformBlock(const string& name, const string& instance = EMPTY_STRING);

    /// Create a new input variable block.
    VariableBlockPtr createInputBlock(const string& name, const string& instance = EMPTY_STRING);

    /// Create a new output variable block.
    VariableBlockPtr createOutputBlock(const string& name, const string& instance = EMPTY_STRING);

    /// Return the uniform variable block with given name.
    VariableBlock& getUniformBlock(const string& name);

    /// Return the uniform variable block with given name.
    const VariableBlock& getUniformBlock(const string& name) const;

    /// Return the input variable block with given name.
    VariableBlock& getInputBlock(const string& name);

    /// Return the input variable block with given name.
    const VariableBlock& getInputBlock(const string& name) const;

    /// Return the output variable block with given name.
    VariableBlock& getOutputBlock(const string& name);

    /// Return the output variable block with given name.
    const VariableBlock& getOutputBlock(const string& name) const;

    /// Return the constant variable block.
    VariableBlock& getConstantBlock();

    /// Return the constant variable block.
    const VariableBlock& getConstantBlock() const;

    /// Return a map of all uniform blocks.
    const VariableBlockMap& getUniformBlocks() const
    {
        return _uniforms;
    }

    /// Return a map of all input blocks.
    const VariableBlockMap& getInputBlocks() const
    {
        return _inputs;
    }

    /// Return a map of all output blocks.
    const VariableBlockMap& getOutputBlocks() const
    {
        return _outputs;
    }

    /// Return a set of all include files
    const StringSet& getIncludes() const
    {
        return _includes;
    }

    /// Return a set of all source dependencies
    const StringSet& getSourceDependencies() const
    {
        return _sourceDependencies;
    }

    /// Start a new scope using the given bracket type.
    void beginScope(Syntax::Punctuation punc = Syntax::CURLY_BRACKETS);

    /// End the current scope.
    void endScope(bool semicolon = false, bool newline = true);

    /// Start a new line.
    void beginLine();

    /// End the current line.
    void endLine(bool semicolon = true);

    /// Add a newline character.
    void newLine();

    /// Add a string.
    void addString(const string& str);

    /// Add a single line of code, optionally appending a semicolon.
    void addLine(const string& str, bool semicolon = true);

    /// Add a single line code comment.
    void addComment(const string& str);

    /// Add a block of code.
    void addBlock(const string& str, const FilePath& sourceFilename, GenContext& context);

    /// Add the contents of an include file if not already present.
    void addInclude(const FilePath& includeFilename, const FilePath& sourceFilename, GenContext& context);

    /// Add a source file dependency for dependency tracking purposes
    void addSourceDependency(const FilePath& file);

    /// Add a value.
    template <typename T>
    void addValue(const T& value)
    {
        StringStream str;
        str << value;
        _code += str.str();
    }

    /// Add the function definition for a node's implementation.
    void addFunctionDefinition(const ShaderNode& node, GenContext& context);

    /// Add the function call for the given node.
    /// This will register the function as being called in the current scope, and code for the
    /// function call will be added to the stage. If emitCode is set to false the code for the
    /// function call will be omitted.
    void addFunctionCall(const ShaderNode& node, GenContext& context, bool emitCode = true);

    /// Return true if the function for the given node has been emitted in the current scope.
    bool isEmitted(const ShaderNode& node, GenContext& context) const;

    /// Set stage function name.
    void setFunctionName(const string& functionName)
    {
        _functionName = functionName;
    }

  private:
    /// Name of the stage
    const string _name;

    /// Name of the stage main function
    string _functionName;

    /// Syntax for the type of shader to generate.
    ConstSyntaxPtr _syntax;

    /// Current indentation level.
    int _indentations;

    /// Current scope.
    vector<Scope> _scopes;

    /// Set of include files that has been included.
    StringSet _includes;

    /// Set of source file dependencies from source code nodes
    StringSet _sourceDependencies;

    /// Set of hash ID's for functions that has been defined.
    std::set<size_t> _definedFunctions;

    /// Block holding constant variables for this stage.
    VariableBlock _constants;

    /// Map of blocks holding uniform variables for this stage.
    VariableBlockMap _uniforms;

    /// Map of blocks holding input variables for this stage.
    VariableBlockMap _inputs;

    /// Map of blocks holding output variables for this stage.
    VariableBlockMap _outputs;

    /// Resulting source code for this stage.
    string _code;

    friend class ShaderGenerator;
};

/// Shared pointer to a ShaderStage
using ShaderStagePtr = std::shared_ptr<ShaderStage>;

/// Utility function for adding a new shader port to a uniform block.
inline ShaderPort* addStageUniform(const string& block,
                                   const TypeDesc* type,
                                   const string& name,
                                   ShaderStage& stage)
{
    VariableBlock& uniforms = stage.getUniformBlock(block);
    return uniforms.add(type, name);
}

/// Utility function for adding a new shader port to an input block.
inline ShaderPort* addStageInput(const string& block,
                                 const TypeDesc* type,
                                 const string& name,
                                 ShaderStage& stage,
                                 bool shouldWiden = false)
{
    VariableBlock& inputs = stage.getInputBlock(block);
    return inputs.add(type, name, {}, shouldWiden);
}

/// Utility function for adding a new shader port to an output block.
inline ShaderPort* addStageOutput(const string& block,
                                  const TypeDesc* type,
                                  const string& name,
                                  ShaderStage& stage,
                                  bool shouldWiden = false)
{
    VariableBlock& outputs = stage.getOutputBlock(block);
    return outputs.add(type, name, {}, shouldWiden);
}

/// Utility function for adding a connector block between stages.
inline void addStageConnectorBlock(const string& block,
                                   const string& instance,
                                   ShaderStage& from,
                                   ShaderStage& to)
{
    from.createOutputBlock(block, instance);
    to.createInputBlock(block, instance);
}

/// Utility function for adding a variable to a stage connector block.
inline void addStageConnector(const string& block,
                              const TypeDesc* type,
                              const string& name,
                              ShaderStage& from,
                              ShaderStage& to,
                              bool shouldWiden = false)
{
    addStageOutput(block, type, name, from, shouldWiden);
    addStageInput(block, type, name, to, shouldWiden);
}

MATERIALX_NAMESPACE_END

#endif