OpenVulkano/openVulkanoCpp/Scene/TextDrawable.cpp

/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#include "TextDrawable.hpp"
#include "Scene/Geometry.hpp"
#include "Scene/Material.hpp"
#include "Scene/Vertex.hpp"
#include "Scene/UniformBuffer.hpp"
#include "Scene/FontAtlasGenerator.hpp"
#include "Base/Logger.hpp"
#include <utf8.h>

namespace OpenVulkano::Scene
{
	using namespace msdfgen;
	using namespace msdf_atlas;

	Shader& TextDrawable::GetDefaultShader()
	{
		static bool once = true;
		static Shader textDefaultShader;
		if (once)
		{
			textDefaultShader.AddShaderProgram(OpenVulkano::ShaderProgramType::VERTEX, "Shader/text");
			textDefaultShader.AddShaderProgram(OpenVulkano::ShaderProgramType::FRAGMENT, "Shader/text");
			textDefaultShader.AddVertexInputDescription(OpenVulkano::Vertex::GetVertexInputDescription());
			textDefaultShader.AddDescriptorSetLayoutBinding(Texture::DESCRIPTOR_SET_LAYOUT_BINDING);
			textDefaultShader.AddDescriptorSetLayoutBinding(UniformBuffer::DESCRIPTOR_SET_LAYOUT_BINDING);
			textDefaultShader.alphaBlend = true;
			textDefaultShader.cullMode = CullMode::NONE;
			once = false;
		}
		return textDefaultShader;
	}

	TextDrawable::TextDrawable(FontAtlasGenerator* fontAtlasGenerator, const TextConfig& config)
	{
		if (!fontAtlasGenerator) { throw std::runtime_error("FontAtlasGenerator is nullptr"); }
		if (fontAtlasGenerator->GetAtlasInfo().empty()) { throw std::runtime_error("Glyphs are not loaded"); }
		m_fontAtlasGenerator = fontAtlasGenerator;
		m_cfg = config;
		m_material.texture = const_cast<Texture*>(&m_fontAtlasGenerator->GetAtlas());
		m_uniBuffer.Init(sizeof(TextConfig), &m_cfg, 3);
	}

	void TextDrawable::GenerateText(const std::string& text, const Math::Vector3f& pos) 
	{
		if (text.empty())
		{
			return;
		}
		// just in case if FontAtlasGenerator changed it's atlas
		m_material.texture = const_cast<Texture*>(&m_fontAtlasGenerator->GetAtlas());
		std::map<unicode_t, GlyphInfo>& symbols = m_fontAtlasGenerator->GetAtlasInfo();
		m_geometry.Close();
		m_geometry.Init(text.size() * 4, text.size() * 6);
		const Texture& atlasTex = *m_material.texture;

		struct Bbox
		{
			double l = 0, r = 0, t = 0, b = 0;
		};

		double cursorX = pos.x;
		auto begin = text.begin();
		auto end = text.end();
		for (size_t i = 0; begin != end; i++)
		{
			unicode_t c = utf8::next(begin, end);
			if (symbols.find(c) != symbols.end())
			{
				Bbox glyphBaselineBbox, glyphAtlasBbox;
				uint32_t vIdx = i * 4;
				uint32_t indices[] = { 1 + vIdx, 2 + vIdx, 3 + vIdx, 1 + vIdx, 3 + vIdx, 0 + vIdx };
				GlyphInfo& info = symbols.at(c);
				info.geometry.getQuadPlaneBounds(glyphBaselineBbox.l, glyphBaselineBbox.b, glyphBaselineBbox.r,
				                                 glyphBaselineBbox.t);
				info.geometry.getQuadAtlasBounds(glyphAtlasBbox.l, glyphAtlasBbox.b, glyphAtlasBbox.r,
				                                 glyphAtlasBbox.t);
				double bearingX = info.glyphBox.bounds.l;
				double bearingY = info.glyphBox.bounds.t;
				double w = glyphBaselineBbox.r - glyphBaselineBbox.l;
				double h = glyphBaselineBbox.t - glyphBaselineBbox.b;
				double l = glyphAtlasBbox.l;
				double r = glyphAtlasBbox.r;
				double t = glyphAtlasBbox.t;
				double b = glyphAtlasBbox.b;
				double ax = cursorX + bearingX;
				double ay = pos.y - (h - bearingY);

				m_geometry.vertices[vIdx].position.x = ax;
				m_geometry.vertices[vIdx].position.y = ay;
				m_geometry.vertices[vIdx].position.z = 1;
				m_geometry.vertices[vIdx].textureCoordinates.x = l / atlasTex.resolution.x;
				m_geometry.vertices[vIdx].textureCoordinates.y = b / atlasTex.resolution.y;
				
				m_geometry.vertices[vIdx + 1].position.x = ax + w;
				m_geometry.vertices[vIdx + 1].position.y = ay;
				m_geometry.vertices[vIdx + 1].position.z = 1;
				m_geometry.vertices[vIdx + 1].textureCoordinates.x = r / atlasTex.resolution.x;
				m_geometry.vertices[vIdx + 1].textureCoordinates.y = b / atlasTex.resolution.y;
				
				m_geometry.vertices[vIdx + 2].position.x = ax + w;
				m_geometry.vertices[vIdx + 2].position.y = ay + h;
				m_geometry.vertices[vIdx + 2].position.z = 1;
				m_geometry.vertices[vIdx + 2].textureCoordinates.x = r / atlasTex.resolution.x;
				m_geometry.vertices[vIdx + 2].textureCoordinates.y = t / atlasTex.resolution.y;
				
				m_geometry.vertices[vIdx + 3].position.x = ax;
				m_geometry.vertices[vIdx + 3].position.y = ay + h;
				m_geometry.vertices[vIdx + 3].position.z = 1;
				m_geometry.vertices[vIdx + 3].textureCoordinates.x = l / atlasTex.resolution.x;
				m_geometry.vertices[vIdx + 3].textureCoordinates.y = t / atlasTex.resolution.y;
				
				m_geometry.SetIndices(indices, 6, 6 * i);
				// TODO: change to lower value(or ideally remove completely) to avoid overlapping and make less space between symbols
				// when setting for depth comparison operator will be available( <= )
				cursorX += info.glyphBox.advance + 0.08;
			}
			else
			{
				// throw ? replace with ? character (if available) ?
				Logger::RENDER->error("Could not find glyph for character {}", c);
			}
		}
		SimpleDrawable::Init(m_shader, &m_geometry, &m_material, &m_uniBuffer);
	}
}