src/CGL430SSBO.cpp

	#include "CGL430SSBO.h"
	#include "U_Log.h"

	CGL430SSBO::~CGL430SSBO()
	{
	if (m_BufferID) { glDeleteBuffers(1, &m_BufferID); }
	}

	void CGL430SSBO::Create(GLsizeiptr size, GLenum usage, GLuint bindingIndex)
	{
	m_Usage = usage;
	m_BindingIndex = bindingIndex;

	glGenBuffers(1, &m_BufferID);
	glBindBuffer(GL_SHADER_STORAGE_BUFFER, m_BufferID);
	glBufferData(GL_SHADER_STORAGE_BUFFER, size, nullptr, m_Usage);
	glBindBufferBase(GL_SHADER_STORAGE_BUFFER, m_BindingIndex, m_BufferID);
	}

	void CGL430SSBO::Bind() const
	{
	glBindBufferBase(GL_SHADER_STORAGE_BUFFER, m_BindingIndex, m_BufferID);
	}

	void* CGL430SSBO::Map(GLenum access)
	{
	glBindBuffer(GL_SHADER_STORAGE_BUFFER, m_BufferID);
	return glMapBuffer(GL_SHADER_STORAGE_BUFFER, access);
	}

	void CGL430SSBO::Unmap()
	{
	glBindBuffer(GL_SHADER_STORAGE_BUFFER, m_BufferID);
	glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
	}

	void CGL430SSBO::UploadData(GLintptr offset, GLsizeiptr size, const void* data)
	{
	glBindBuffer(GL_SHADER_STORAGE_BUFFER, m_BufferID);
	glBufferSubData(GL_SHADER_STORAGE_BUFFER, offset, size, data);
	}

	bool CGL430SSBO::ReflectStructArray(GLuint program, const std::string& blockName, const std::string& arrayName)
	{
	m_FieldMap.clear();
	m_ArrayStride = 0;

	GLuint blockIndex = glGetProgramResourceIndex(program, GL_SHADER_STORAGE_BLOCK, blockName.c_str());
	if (blockIndex == GL_INVALID_INDEX) { return false; }

	GLint numVars = 0;
	glGetProgramInterfaceiv(program, GL_BUFFER_VARIABLE, GL_ACTIVE_RESOURCES, &numVars);

	const GLenum props[] = { GL_NAME_LENGTH, GL_OFFSET, GL_ARRAY_STRIDE };

	for (int i = 0; i < numVars; ++i)
	{
	GLint nameLen = 0;
	glGetProgramResourceiv(program, GL_BUFFER_VARIABLE, i, 1, (GLenum[]){ GL_NAME_LENGTH }, 1, nullptr, &nameLen);

	std::vector<GLchar> name(nameLen);
	glGetProgramResourceName(program, GL_BUFFER_VARIABLE, i, nameLen, nullptr, name.data());
	std::string fullName(name.data());

	std::string prefix = arrayName + "[0].";
	if (!fullName.starts_with(prefix)) continue;

	std::string fieldName = fullName.substr(prefix.length());

	FieldInfo f;
	f.Name = fieldName;

	glGetProgramResourceiv(program, GL_BUFFER_VARIABLE, i, 1, (GLenum[]){ GL_OFFSET }, 1, nullptr, &f.Offset);

	GLint arrayStride = 0;
	GLenum strideProp = GL_ARRAY_STRIDE;
	glGetProgramResourceiv(program, GL_BUFFER_VARIABLE, i, 1, &strideProp, 1, nullptr, &arrayStride);

	if (arrayStride > 0)
	{
	m_ArrayStride = arrayStride;
	}

	m_FieldMap[fieldName] = f;
	}
	Log::Instance() << "Array stride is " << m_ArrayStride << Log::Endl;
	return true;
	}

	bool CGL430SSBO::ReflectFields(GLuint program, const std::string& blockName)
	{
	m_FieldMap.clear();
	m_ArrayStride = 0;

	GLuint blockIndex = glGetProgramResourceIndex(program, GL_SHADER_STORAGE_BLOCK, blockName.c_str());
	if (blockIndex == GL_INVALID_INDEX) { return false; }

	GLint numVars = 0;
	glGetProgramInterfaceiv(program, GL_BUFFER_VARIABLE, GL_ACTIVE_RESOURCES, &numVars);

	const GLenum props[] = { GL_NAME_LENGTH, GL_OFFSET };

	for (int i = 0; i < numVars; ++i)
	{
	GLint nameLen = 0;
	glGetProgramResourceiv(program, GL_BUFFER_VARIABLE, i, 1, &props[0], 1, nullptr, &nameLen);

	std::vector<GLchar> name(nameLen);
	glGetProgramResourceName(program, GL_BUFFER_VARIABLE, i, nameLen, nullptr, name.data());
	std::string fieldName(name.data());

	GLint values[2];
	glGetProgramResourceiv(program, GL_BUFFER_VARIABLE, i, 2, &props[1], 2, nullptr, values);

	FieldInfo f;
	f.Name = fieldName;
	f.Offset = values[0];

	m_FieldMap[fieldName] = f;
	}

	return true;
	}

	GLint CGL430SSBO::GetArrayStride() const
	{
	return m_ArrayStride;
	}

	GLint CGL430SSBO::GetFieldOffset(const std::string& fieldName, int arrayIndex) const
	{
	auto it = m_FieldMap.find(fieldName);
	if (it == m_FieldMap.end()) { return -1; }

	return it->second.Offset + arrayIndex * m_ArrayStride;
	}