JoltPhysics/TestFramework/Renderer/Font.h

// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT

#pragma once

#include <Jolt/Core/Reference.h>
#include <Jolt/Core/Color.h>
#include <Jolt/Math/Float2.h>
#include <Renderer/RenderPrimitive.h>
#include <Renderer/Texture.h>
#include <Renderer/PipelineState.h>
#include <memory>

class Renderer;
class Texture;

/// Font class, used to display text in 3D mode. Does variable width fonts with kerning. Font names are identical to the Windows font names.
class Font : public RefTarget<Font>
{
public:
	/// Constants
	static const int cBeginChar	= ' ';												///< First character that is drawable in the character set
	static const int cEndChar	= 256;												///< Last character + 1 that is drawable in the character set
	static const int cNumChars	= cEndChar - cBeginChar;							///< Number of drawable characters in the character set

	/// Constructor
								Font(Renderer *inRenderer);

	/// Create a font
	bool						Create(const char *inFontName, int inCharHeight);

	/// Properties
	const String &				GetFontName() const									{ return mFontName; }
	int							GetCharHeight() const								{ return mCharHeight; }

	/// Get extents of a string, assuming the height of the text is 1 and with the normal aspect ratio of the font
	Float2						MeasureText(const string_view &inText) const;

	/// Draw a string at a specific location
	/// If the string is drawn with the identity matrix, it's top left will start at (0, 0, 0)
	/// The text width is in the X direction and the text height is in the Y direction and it will have a height of 1
	void						DrawText3D(Mat44Arg inTransform, const string_view &inText, ColorArg inColor = Color::sWhite) const;

private:
	/// Create a primitive for a string
	bool						CreateString(Mat44Arg inTransform, const string_view &inText, ColorArg inColor, RenderPrimitive &ioPrimitive) const;

	struct FontVertex
	{
		Float3					mPosition;
		Float2					mTexCoord;
		Color					mColor;
	};

	/// Properties of the font
	String						mFontName;											///< Name of the font
	int							mCharHeight;										///< Height of a character
	int							mHorizontalTexels;									///< Number of texels horizontally, determines the scale of mStartU, mWidth and mSpacing
	int							mVerticalTexels;									///< Number of texels vertically, determines the scale of mStartV
	uint16						mStartU[cNumChars] = {};							///< Start U in texels
	uint16						mStartV[cNumChars] = {};							///< Start V in texels
	uint8						mWidth[cNumChars] = {};								///< Width of character in texels
	uint8						mSpacing[cNumChars][cNumChars] = {};				///< Spacing between characters in texels

	/// Structures used for drawing
	Renderer *					mRenderer;											///< Our renderer
	Ref<Texture>				mTexture;											///< The texture containing all characters
	unique_ptr<PipelineState>	mPipelineState;										///< The state used to render characters
};