SDF-font loading example added

examples/text/font_sdf/OFL.txt

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+Copyright (c) 2009, Mark Simonson (http://www.ms-studio.com, mark@marksimonson.com),
+with Reserved Font Name Anonymous Pro.
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+https://openfontlicense.org
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded, 
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.

examples/text/font_sdf/main.go

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+package main
+
+import (
+	_ "embed"
+	"fmt"
+	"unsafe"
+
+	rl "github.com/gen2brain/raylib-go/raylib"
+)
+
+//go:embed AnonymousPro-Bold.ttf
+var fileData []byte
+
+func main() {
+	// Initialization
+	const screenWidth, screenHeight = 800, 450
+	rl.InitWindow(screenWidth, screenHeight, "raylib [text] example - SDF fonts")
+	defer rl.CloseWindow() // Close window and OpenGL context
+
+	// NOTE: Textures/Fonts MUST be loaded after Window initialization (OpenGL context is required)
+
+	const msg = "Signed Distance Fields"
+
+	// Default font generation from TTF font
+	fontDefault := rl.Font{BaseSize: 16, CharsCount: 95}
+	defer rl.UnloadFont(fontDefault) // Default font unloading
+
+	// Loading font data from memory data
+	// Parameters > font size: 16, no glyphs array provided (nil), glyphs count: 95 (autogenerate chars array)
+	glyphs := rl.LoadFontData(fileData, 16, nil, 95, rl.FontDefault)
+	fontDefault.Chars = &glyphs[0]
+
+	// Parameters >  font size: 16, glyphs padding in image: 4 px, pack method: 0 (default)
+	atlas := rl.GenImageFontAtlas(unsafe.Slice(fontDefault.Chars, fontDefault.CharsCount), unsafe.Slice(&fontDefault.Recs, fontDefault.CharsCount), 16, 4, 0)
+	fontDefault.Texture = rl.LoadTextureFromImage(&atlas)
+	rl.UnloadImage(&atlas)
+
+	// SDF font generation from TTF font
+	fontSDF := rl.Font{BaseSize: 16, CharsCount: 95}
+	defer rl.UnloadFont(fontSDF) // SDF font unloading
+
+	// Parameters > font size: 16, no glyphs array provided (nil), glyphs count: 0 (defaults to 95)
+	glyphsSDF := rl.LoadFontData(fileData, 16, nil, 0, rl.FontSdf)
+	fontSDF.Chars = &glyphsSDF[0]
+	// Parameters > font size: 16, glyphs padding in image: 0 px, pack method: 1 (Skyline algorithm)
+	atlas = rl.GenImageFontAtlas(unsafe.Slice(fontSDF.Chars, fontSDF.CharsCount), unsafe.Slice(&fontSDF.Recs, fontSDF.CharsCount), 16, 0, 1)
+	fontSDF.Texture = rl.LoadTextureFromImage(&atlas)
+	rl.UnloadImage(&atlas)
+
+	// Load SDF required shader (we use default vertex shader)
+	shader := rl.LoadShader("", "sdf.fs")
+	defer rl.UnloadShader(shader)                           // Unload SDF shader
+	rl.SetTextureFilter(fontSDF.Texture, rl.FilterBilinear) // Required for SDF font
+
+	fontPosition := rl.NewVector2(40, screenHeight/2.0-50)
+	textSize := rl.Vector2Zero()
+	fontSize := float32(16)
+	currentFont := 0 // 0 - fontDefault, 1 - fontSDF
+
+	rl.SetTargetFPS(60) // Set our game to run at 60 frames-per-second
+
+	// Main game loop
+	for !rl.WindowShouldClose() { // Detect window close button or ESC key
+		fontSize += rl.GetMouseWheelMove() * 8.0
+
+		if fontSize < 6 {
+			fontSize = 6
+		}
+
+		if rl.IsKeyDown(rl.KeySpace) {
+			currentFont = 1
+			textSize = rl.MeasureTextEx(fontSDF, msg, fontSize, 0)
+		} else {
+			currentFont = 0
+			textSize = rl.MeasureTextEx(fontDefault, msg, fontSize, 0)
+		}
+
+		fontPosition.X = float32(rl.GetScreenWidth()/2) - textSize.X/2
+		fontPosition.Y = float32(rl.GetScreenHeight()/2) - textSize.Y/2 + 80
+
+		rl.BeginDrawing()
+		rl.ClearBackground(rl.RayWhite)
+
+		if currentFont == 1 {
+			// NOTE: SDF fonts require a custom SDf shader to compute fragment color
+			rl.BeginShaderMode(shader) // Activate SDF font shader
+			rl.DrawTextEx(fontSDF, msg, fontPosition, fontSize, 0, rl.Black)
+			rl.EndShaderMode() // Activate our default shader for next drawings
+			rl.DrawTexture(fontSDF.Texture, 10, 10, rl.Black)
+			rl.DrawText("SDF!", 320, 20, 80, rl.Red)
+		} else {
+			rl.DrawTextEx(fontDefault, msg, fontPosition, fontSize, 0, rl.Black)
+			rl.DrawTexture(fontDefault.Texture, 10, 10, rl.Black)
+			rl.DrawText("default font", 315, 40, 30, rl.Gray)
+		}
+
+		rl.DrawText("FONT SIZE: 16.0", int32(rl.GetScreenWidth()-240), 20, 20, rl.DarkGray)
+		rl.DrawText(fmt.Sprintf("RENDER SIZE: %02.02f", fontSize), int32(rl.GetScreenWidth()-240), 50, 20, rl.DarkGray)
+		rl.DrawText("Use MOUSE WHEEL to SCALE TEXT!", int32(rl.GetScreenWidth()-240), 90, 10, rl.DarkGray)
+
+		rl.DrawText("HOLD SPACE to USE SDF FONT VERSION!", 340, int32(rl.GetScreenHeight()-30), 20, rl.Maroon)
+
+		rl.EndDrawing()
+
+	}
+}

examples/text/font_sdf/sdf.fs

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+#version 330
+
+// Input vertex attributes (from vertex shader)
+in vec2 fragTexCoord;
+in vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform vec4 colDiffuse;
+
+// Output fragment color
+out vec4 finalColor;
+
+// NOTE: Add here your custom variables
+
+void main()
+{
+    // Texel color fetching from texture sampler
+    // NOTE: Calculate alpha using signed distance field (SDF)
+    float distanceFromOutline = texture(texture0, fragTexCoord).a - 0.5;
+    float distanceChangePerFragment = length(vec2(dFdx(distanceFromOutline), dFdy(distanceFromOutline)));
+    float alpha = smoothstep(-distanceChangePerFragment, distanceChangePerFragment, distanceFromOutline);
+
+    // Calculate final fragment color
+    finalColor = vec4(fragColor.rgb, fragColor.a*alpha);
+}