Move glyph creation for text to render function instead of in set string, clear font glyph background before rendering the text

4 files changed, 32 insertions, 25 deletions

diff --git a/include/mgl/graphics/font.h b/include/mgl/graphics/font.h
index 4bd0428..118a867 100644
--- a/include/mgl/graphics/font.h
+++ b/include/mgl/graphics/font.h
@@ -25,7 +25,8 @@ typedef struct {
 } mgl_font_atlas;
 
 struct mgl_font {
-    mgl_texture texture; /* Font texture coordinates are in pixel space */
+    /* Font texture coordinates are in pixel space. Note: the texture id may change */
+    mgl_texture texture;
     mgl_font_atlas font_atlas;
     unsigned int character_size;
     mgl_font_char_map char_map;
diff --git a/include/mgl/graphics/text.h b/include/mgl/graphics/text.h
index 08a6c37..89ae541 100644
--- a/include/mgl/graphics/text.h
+++ b/include/mgl/graphics/text.h
@@ -22,6 +22,7 @@ typedef struct {
     mgl_color color;
     mgl_vec2f position;
     mgl_vec2f bounds;
+    bool bounds_dirty;
 } mgl_text;
 
 /*
@@ -40,7 +41,7 @@ void mgl_text_set_string(mgl_text *self, const char *str, size_t str_size);
 void mgl_text_set_font(mgl_text *self, mgl_font *font);
 void mgl_text_set_position(mgl_text *self, mgl_vec2f position);
 void mgl_text_set_color(mgl_text *self, mgl_color color);
-mgl_vec2f mgl_text_get_bounds(const mgl_text *self);
+mgl_vec2f mgl_text_get_bounds(mgl_text *self);
 /* Returns the position of the character on the screen (relative to the current mgl_view) */
 mgl_vec2f mgl_text_find_character_pos(mgl_text *self, size_t index);
 void mgl_text_draw(mgl_context *context, mgl_text *text);
diff --git a/src/graphics/font.c b/src/graphics/font.c
index 17362f6..aa349a6 100644
--- a/src/graphics/font.c
+++ b/src/graphics/font.c
@@ -4,8 +4,8 @@
 #define STB_TRUETYPE_IMPLEMENTATION
 #include "../../external/stb_truetype.h"
 
-/* Need padding so filtering doesn't touch pixels in another glyphs area. TODO: Decrease this */
-#define GLYPH_PADDING 4
+/* Need padding so filtering doesn't touch pixels in another glyphs area */
+#define GLYPH_PADDING 2
 #define GLYPH_UPSAMPLE 1
 
 int mgl_font_load_from_file(mgl_font *self, const mgl_memory_mapped_file *mapped_file, unsigned int character_size) {
@@ -36,11 +36,6 @@ int mgl_font_load_from_file(mgl_font *self, const mgl_memory_mapped_file *mapped
         return -1;
     }
 
-    if(mgl_texture_init(&self->texture) != 0) {
-        mgl_font_unload(self);
-        return -1;
-    }
-
     /* TODO: Use stbtt_GetCodepointSDF */
     return 0;
 }
@@ -130,12 +125,16 @@ static void mgl_font_handle_new_render_position(mgl_font *self, int glyph_width)
 
 int mgl_font_get_glyph(mgl_font *self, uint32_t codepoint, mgl_font_glyph *glyph) {
     if(self->font_atlas.width == 0) {
+        if(self->texture.id == 0 && mgl_texture_init(&self->texture) != 0)
+            return -1;
+
         const int initial_atlas_size = align_up_to_next_value_of(128, self->character_size);
         /* TODO: Scale by character size */
         mgl_texture_load_options load_options = {
             .compressed = false,
             .pixel_coordinates = true
         };
+
         if(mgl_texture_load_from_memory(&self->texture, NULL, initial_atlas_size, initial_atlas_size, MGL_IMAGE_FORMAT_ALPHA, &load_options) == 0) {
             /*fprintf(stderr, "Error: failed to create font atlas texture, error: mgl_texture_load_from_memory failed\n");*/
             self->font_atlas.width = initial_atlas_size;
@@ -176,12 +175,13 @@ int mgl_font_get_glyph(mgl_font *self, uint32_t codepoint, mgl_font_glyph *glyph
     int yoff = y0;
 
     /* TODO: Use stbtt_MakeGlyphBitmapSubpixelPrefilter instead for better text quality */
-    const size_t pixels_size = (width + GLYPH_PADDING * 2) * (height + GLYPH_PADDING * 2);
-    unsigned char *pixels = malloc(pixels_size);
+    const size_t pixels_width = (width + GLYPH_PADDING * 2);
+    const size_t pixels_height = (height + GLYPH_PADDING * 2);
+    const size_t pixels_size = pixels_width * pixels_height;
+    unsigned char *pixels = calloc(pixels_size, 1);
     if(pixels) {
-        /* TODO: Is this needed? */
-        /*memset(pixels, 0, pixels_size);*/
-        stbtt_MakeGlyphBitmapSubpixel(self->font_info, pixels, width, height, width, font_scale, font_scale, GLYPH_PADDING, GLYPH_PADDING, glyph_index);
+        const int top_padding = GLYPH_PADDING;
+        stbtt_MakeGlyphBitmap(self->font_info, pixels + pixels_width * top_padding + GLYPH_PADDING, width, height, pixels_width, font_scale, font_scale, glyph_index);
     }
 
     mgl_vec2i render_offset;
@@ -223,7 +223,7 @@ int mgl_font_get_glyph(mgl_font *self, uint32_t codepoint, mgl_font_glyph *glyph
         }
     }
 
-    const int res = mgl_texture_update(&self->texture, pixels, render_offset.x, render_offset.y, width, height, MGL_IMAGE_FORMAT_ALPHA);
+    const int res = mgl_texture_update(&self->texture, pixels, render_offset.x - GLYPH_PADDING, render_offset.y - GLYPH_PADDING, pixels_width, pixels_height, MGL_IMAGE_FORMAT_ALPHA);
     free(pixels);
     return res;
 }
diff --git a/src/graphics/text.c b/src/graphics/text.c
index 3620659..66ef7e3 100644
--- a/src/graphics/text.c
+++ b/src/graphics/text.c
@@ -90,6 +90,7 @@ void mgl_text_init(mgl_text *self, mgl_font *font, const char *str, size_t str_s
     self->position = (mgl_vec2f){ 0.0f, 0.0f };
     self->text = NULL;
     self->text_size = 0;
+    self->bounds_dirty = true;
     mgl_text_set_string(self, str, str_size);
 }
 
@@ -105,19 +106,13 @@ void mgl_text_set_string(mgl_text *self, const char *str, size_t str_size) {
     self->text = str;
     self->text_size = str_size;
     if(self->text && self->text_size > 0 && self->font)
-        self->bounds = mgl_text_calculate_bounds(self);
-    else
-        self->bounds = (mgl_vec2f){ 0.0f, 0.0f };
+        self->bounds_dirty = true;
 }
 
 void mgl_text_set_font(mgl_text *self, mgl_font *font) {
     self->font = font;
-    if(self->font) {
-        if(self->bounds.x < 0.001f && self->bounds.y < 0.001f && self->text && self->text_size > 0)
-            self->bounds = mgl_text_calculate_bounds(self);
-    } else {
-        self->bounds = (mgl_vec2f){ 0.0f, 0.0f };
-    }
+    if(self->text && self->text_size > 0 && self->font)
+        self->bounds_dirty = true;
 }
 
 void mgl_text_set_position(mgl_text *self, mgl_vec2f position) {
@@ -128,7 +123,14 @@ void mgl_text_set_color(mgl_text *self, mgl_color color) {
     self->color = color;
 }
 
-mgl_vec2f mgl_text_get_bounds(const mgl_text *self) {
+mgl_vec2f mgl_text_get_bounds(mgl_text *self) {
+    if(self->bounds_dirty) {
+        self->bounds_dirty = false;
+        if(self->text && self->text_size > 0 && self->font)
+            self->bounds = mgl_text_calculate_bounds(self);
+        else
+            self->bounds = (mgl_vec2f){ 0.0f, 0.0f };
+    }
     return self->bounds;
 }
 
@@ -210,6 +212,9 @@ void mgl_text_draw(mgl_context *context, mgl_text *text) {
     if(!text->text || text->text_size == 0 || !text->font)
         return;
 
+    /* Calculate bounds beforehand if needed, which also generates glyphs because opengl outputs an error if that is done inside glBegin/glEnd */
+    mgl_text_get_bounds(text);
+
     TextDrawUserdata text_draw_userdata;
     text_draw_userdata.position = (mgl_vec2f){ text->position.x, text->position.y + text->font->character_size };
     text_draw_userdata.text = text;