feat(rendering): stroked text

core/src/rendering/font.cpp

@@ -10,6 +10,7 @@
 
 #include <ft2build.h>
 #include FT_FREETYPE_H
+#include FT_STROKER_H
 
 // https://learnopengl.com/In-Practice/Text-Rendering
 
@@ -52,6 +53,34 @@ void fontFinish() {
     }
 }
 
+static void loadCharTexture(FT_Face& face, FT_BitmapGlyph& glyph_bitmap, Character& character) {
+    // Generate texture
+    unsigned int texture;
+    glGenTextures(1, &texture);
+    glBindTexture(GL_TEXTURE_2D, texture);
+    glTexImage2D(
+        GL_TEXTURE_2D,
+        0,
+        GL_RED,
+        glyph_bitmap->bitmap.width,
+        glyph_bitmap->bitmap.rows,
+        0,
+        GL_RED,
+        GL_UNSIGNED_BYTE,
+        glyph_bitmap->bitmap.buffer
+    );
+    // set texture options
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    // now store character for later use
+    character.ID = texture;
+    character.size = glm::ivec2(glyph_bitmap->bitmap.width, glyph_bitmap->bitmap.rows);
+    character.bearing = glm::ivec2(glyph_bitmap->left, glyph_bitmap->top);
+    character.advance = (unsigned int)face->glyph->advance.x;
+}
+
 std::shared_ptr<Font> loadFont(std::string fontName) {
     std::string fontPath = "assets/font/" + fontName;
 
@@ -66,50 +95,53 @@ std::shared_ptr<Font> loadFont(std::string fontName) {
     FT_Set_Pixel_Sizes(face, 0, 16);
     font->height = face->size->metrics.y_ppem;
 
+    FT_Stroker stroker;
+    FT_Stroker_New(freetype, &stroker);
+    FT_Stroker_Set(stroker, 2 * 64, FT_STROKER_LINECAP_ROUND, FT_STROKER_LINEJOIN_ROUND, 0);
+
     // Load each glyph
     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
     for (unsigned char c = 0; c < 128; c++) {
         // load character glyph 
-        if (FT_Error err = FT_Load_Char(face, c, FT_LOAD_RENDER)) {
+        if (FT_Error err = FT_Load_Char(face, c, FT_LOAD_DEFAULT)) {
             Logger::errorf("Failed to load glyph %d in font '%s': [%d]", c, fontName.c_str(), err);
             continue;
         }
 
-        // Generate texture
+        FT_Glyph glyph;
-        unsigned int texture;
+        FT_BitmapGlyph glyph_bitmap;
-        glGenTextures(1, &texture);
+    
-        glBindTexture(GL_TEXTURE_2D, texture);
-        glTexImage2D(
-            GL_TEXTURE_2D,
-            0,
-            GL_RED,
-            face->glyph->bitmap.width,
-            face->glyph->bitmap.rows,
-            0,
-            GL_RED,
-            GL_UNSIGNED_BYTE,
-            face->glyph->bitmap.buffer
-        );
-        // set texture options
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-        // now store character for later use
         Character character;
-        character.ID = texture;
+
-        character.size = glm::ivec2(face->glyph->bitmap.width, face->glyph->bitmap.rows);
+        // Render base
-        character.bearing = glm::ivec2(face->glyph->bitmap_left, face->glyph->bitmap_top);
+        FT_Get_Glyph(face->glyph, &glyph);
-        character.advance = (unsigned int)face->glyph->advance.x;
+        FT_Glyph_To_Bitmap(&glyph, FT_RENDER_MODE_NORMAL, nullptr, true);
+        glyph_bitmap = (FT_BitmapGlyph)glyph;
+
+        loadCharTexture(face, glyph_bitmap, character);
         font->characters[c] = character;
+        FT_Done_Glyph(glyph);
+        // TODO: Find out how to clear FT_BitmapGlyph... I cant import FT_Bitmap_Done for some reason
+
+        // Render stroked
+        // https://stackoverflow.com/a/28078293/16255372
+        FT_Get_Glyph(face->glyph, &glyph);
+        FT_Glyph_StrokeBorder(&glyph, stroker, false, true);
+        FT_Glyph_To_Bitmap(&glyph, FT_RENDER_MODE_NORMAL, nullptr, true);
+        glyph_bitmap = reinterpret_cast<FT_BitmapGlyph>(glyph);
+
+        loadCharTexture(face, glyph_bitmap, character);
+        font->strokeCharacters[c] = character;
+        FT_Done_Glyph(glyph);
     }
     
+    FT_Stroker_Done(stroker);
     FT_Done_Face(face);
 
     return font;
 }
 
-void drawText(std::shared_ptr<Font> font, std::string text, float x, float y, float scale, glm::vec3 color) {
+void drawText(std::shared_ptr<Font> font, std::string text, float x, float y, float scale, glm::vec3 color, bool drawStroke) {
     // activate corresponding render state
     glDisable(GL_CULL_FACE);
     glDisable(GL_DEPTH_TEST);
@@ -129,7 +161,7 @@ void drawText(std::shared_ptr<Font> font, std::string text, float x, float y, fl
     // iterate through all characters
     for (size_t i = 0; i < text.size(); i++) {
         unsigned char c = text[i];
-        Character ch = font->characters[c];
+        Character ch = drawStroke ? font->strokeCharacters[c] : font->characters[c];
 
         float xpos = x + ch.bearing.x * scale;
         float ypos = viewportHeight - y - font->height - (ch.size.y - ch.bearing.y) * scale;

core/src/rendering/font.h

@@ -16,10 +16,11 @@ struct Character {
 struct Font {
     unsigned int height;
     Character characters[128];
+    Character strokeCharacters[128];
 };
 
 void fontInit();
 void fontFinish();
 std::shared_ptr<Font> loadFont(std::string fontName);
-void drawText(std::shared_ptr<Font> font, std::string text, float x, float y, float scale=1.f, glm::vec3 color = glm::vec3(1,1,1));
+void drawText(std::shared_ptr<Font> font, std::string text, float x, float y, float scale=1.f, glm::vec3 color = glm::vec3(1,1,1), bool drawStroke = false);
 float calcTextWidth(std::shared_ptr<Font> font, std::string text, float scale = 1.f);