Refactoring font rendering

4 files changed, 82 insertions, 47 deletions

diff --git a/code/amr_fonts.h b/code/amr_fonts.h
new file mode 100644
index 0000000..f44893c
--- /dev/null
+++ b/code/amr_fonts.h
@@ -0,0 +1,51 @@
+#ifndef AMR_FONTS_H
+#define AMR_FONTS_H
+
+typedef struct amr_glyph_info {
+  u32 charset_start_index;
+  u32 charset_end_index;
+} amr_glyph_info;
+
+typedef struct amr_font_details_debug {
+  i32 advance;
+  i32 lsb;
+  i32 x0, y0, x1, y1;
+  i32 kern;
+  f32 lx;
+  f32 ly;
+  i32 byte_offset;
+  i32 baseline;
+} debug_font_details;
+
+typedef struct amr_font_state_debug {
+  stbtt_fontinfo font_info;
+} amr_font_state;
+// initialise a font and loads the font in the fontbuffer
+// input: 
+// - font path
+// - font buffer, must be initialised by caller
+// - size of the font file, must be known beforehand
+// output:
+// - error code
+u32 amr_InitFont(const u8 *FontPath, u8 *FontBuffer, u32 FontFz); 
+u32 amr_GetGlyphIdFromCodepoint(amr_glyph_info glyph, u32 *GlyphIndexArray, u32 Codepoint);
+
+u32 amr_InitFont(stbtt_fontinfo *font_info, const char *FontPath, u8 *FontBuffer, u32 FontSz)
+{
+  PlatformDebugFileRead(FontPath, FontBuffer, FontSz);
+  if (!stbtt_InitFont(font_info, FontBuffer, 0))
+  {
+    printf("ERROR: failed to read arial font");
+    assert(1 == 0);
+  }
+
+  return 0;
+}
+
+u32 amr_GetGlyphIdFromCodepoint(amr_glyph_info glyph, u32 *GlyphIndexArray, u32 Codepoint)
+{
+  u32 glyph_id = *(GlyphIndexArray + (Codepoint - glyph.charset_start_index));
+  return glyph_id;
+}
+
+#endif
diff --git a/code/game_main.h b/code/game_main.h
index 2194e27..1b4e1af 100644
--- a/code/game_main.h
+++ b/code/game_main.h
@@ -33,17 +33,6 @@ typedef struct Rect2 {
   Vec2 br;
 } Rect2;
 
-typedef struct debug_font_details {
-  i32 advance;
-  i32 lsb;
-  i32 x0, y0, x1, y1;
-  i32 kern;
-  f32 lx;
-  f32 ly;
-  i32 byte_offset;
-  i32 baseline;
-} debug_font_details;
-
 typedef struct GameState {
   GameCamera Camera;
   GameInput Input;
diff --git a/code/math.h b/code/math.h
index ca5e96e..2ab7ac3 100644
--- a/code/math.h
+++ b/code/math.h
@@ -42,8 +42,8 @@ typedef struct Vec2 {
   Vec2 operator/(f32 s)
   {
     Vec2 R = {0};
-    R.x = x/2;
-    R.y = y/2;
+    R.x = x/s;
+    R.y = y/s;
     return R;
   }
 
@@ -191,8 +191,6 @@ Vec3 CrossProductVec3(Vec3 S, Vec3 K)
     return R;
 }
 
-
-
 // @note: I am creating vectors in many places so created a function to make initialising abit easier
 Vec4 InitVec4(f32 x, f32 y, f32 z, f32 w)
 {
diff --git a/code/win32_main.cpp b/code/win32_main.cpp
index 208e85a..4ba86e1 100644
--- a/code/win32_main.cpp
+++ b/code/win32_main.cpp
@@ -33,6 +33,9 @@ typedef  double   f64;
 #define internal static
 
 /**
+ * - enhance filereading to read bytes
+ * error todo:
+ * - start having error codes to help with error detection in case something went wrong in functions
  * Font rendering todos:
  * - Look into font-packing, what is that? why is it needed?
  * - Look into generating a single bitmap and then extracting characters from the 
@@ -41,13 +44,14 @@ typedef  double   f64;
  * */
 internal i64 GlobalPerfCountFrequency;
 
-i8 PlatformDebugReadFile(char *FileName, void *FileBuffer, u32 MaxSize, LPDWORD BytesRead)
+u8 PlatformDebugFileRead(const char *FileName, void *FileBuffer, u32 MaxSize)
 {
   // @todo: refactor function, check for closehandle error codes
-  HANDLE FileHandle = CreateFileA(FileName, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+  HANDLE FileHandle = CreateFileA(FileName, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
   if (FileHandle != INVALID_HANDLE_VALUE)
   {
-    if (ReadFile(FileHandle, FileBuffer, MaxSize, BytesRead, NULL) != 0)
+    DWORD BytesRead;
+    if (ReadFile(FileHandle, FileBuffer, MaxSize, &BytesRead, NULL) != 0)
     {
       CloseHandle(FileHandle);
       return 1;
@@ -100,19 +104,10 @@ Win32GetSecondsElapsed(LARGE_INTEGER Start, LARGE_INTEGER End)
 
 #include "amr_memory.c"
 #include "gl_graphics.cpp"
+//#include "amr_camera.c"
+#include "amr_fonts.h"
 #include "game_main.h"
 
-typedef struct amr_glyph_info {
-  u32 charset_start_index;
-  u32 charset_end_index;
-} amr_glyph_info;
-
-u32 amr_GetGlyphIdFromCodepoint(amr_glyph_info glyph, u32 *GlyphIndexArray, u32 Codepoint)
-{
-  u32 glyph_id = *(GlyphIndexArray + (Codepoint - glyph.charset_start_index));
-  return glyph_id;
-}
-
 int main()
 {
     // ==================== PROGRAM STATE INITIALISATION =====================
@@ -184,14 +179,14 @@ int main()
     DWORD BytesRead = 0;
     u32 max_fsz = MB((u64)5);
     u8 *vs_file = (u8 *)amr_ArenaAlloc(&State.Memory.Arena, max_fsz);
-    if (PlatformDebugReadFile("./code/shaders/text.vs.glsl", vs_file, max_fsz, &BytesRead) != 1)
+    if (PlatformDebugFileRead("./code/shaders/text.vs.glsl", vs_file, max_fsz) != 1)
     {
       printf("ERROR: failed to open text vertex shader");
       return -1;
     }
 
     u8 *fs_file = (u8 *)amr_ArenaAlloc(&State.Memory.Arena, max_fsz);
-    if (PlatformDebugReadFile("./code/shaders/text.fs.glsl", fs_file, max_fsz, &BytesRead) != 1)
+    if (PlatformDebugFileRead("./code/shaders/text.fs.glsl", fs_file, max_fsz) != 1)
     {
       printf("ERROR: failed to open text vertex shader");
       return -1;
@@ -204,25 +199,24 @@ int main()
     amr_ArenaFreeAll(&State.Memory.Arena);
 
     // =================== FONT RENDERING ===================
+    // @resume: abstracting font rendering to draw text easily
+    // --------- Init Font -----------------
+    // input:
+    // - filepath, memory buffer, memory buffer size
+    // - maybe a font_object reference that I need
     u32 font_fz = MB(2);
     u8 *ArialBuffer = (u8 *)amr_ArenaAlloc(&State.Memory.Arena, font_fz);
+    amr_font_state ArialFontState = {0};
 
-    // @todo: change to PlatformDebugFileRead
-    fread(ArialBuffer, 1, font_fz, fopen("c:/windows/fonts/arial.ttf", "rb"));
-
-    stbtt_fontinfo font_info;
-    if (!stbtt_InitFont(&font_info, ArialBuffer, 0))
-    {
-      printf("ERROR: failed to read arial font");
-      assert(1 == 0);
-    }
+    amr_InitFont(&(ArialFontState.font_info), "c:/windows/fonts/arial.ttf", ArialBuffer, font_fz);
 
+    ///////////////////////////////////// PREPARE TEXT INFO ///////////////////
     // get a SF (scale factor)
-    f32 SF = stbtt_ScaleForPixelHeight(&font_info, 32.0f);
+    f32 SF = stbtt_ScaleForPixelHeight(&(ArialFontState.font_info), 32.0f);
 
     // get vertical metrics
     i32 f_ascent, f_descent, f_line_gap;
-    stbtt_GetFontVMetrics(&font_info, &f_ascent, &f_descent, &f_line_gap);
+    stbtt_GetFontVMetrics(&(ArialFontState.font_info), &f_ascent, &f_descent, &f_line_gap);
 
     // ========================= GLYPH AND FONT INFO STORAGE ================
     amr_glyph_info latin_basic = {32, 126};
@@ -231,7 +225,7 @@ int main()
     u32 *glyph_array_iter = GlyphIndexArray;
     for (u32 i = 0; i < glyph_count; i++)
     {
-      *glyph_array_iter = stbtt_FindGlyphIndex(&font_info, latin_basic.charset_start_index + i);
+      *glyph_array_iter = stbtt_FindGlyphIndex(&(ArialFontState.font_info), latin_basic.charset_start_index + i);
        glyph_array_iter++;
     }
 
@@ -260,8 +254,8 @@ int main()
         continue;
       }
 
-      stbtt_GetGlyphHMetrics(&font_info, amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i]), &_fi->advance, &_fi->lsb);
-      stbtt_GetGlyphBitmapBox(&font_info, amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i]), SF, SF, &_fi->x0, &_fi->y0, &_fi->x1, &_fi->y1);
+      stbtt_GetGlyphHMetrics(&(ArialFontState.font_info), amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i]), &_fi->advance, &_fi->lsb);
+      stbtt_GetGlyphBitmapBox(&(ArialFontState.font_info), amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i]), SF, SF, &_fi->x0, &_fi->y0, &_fi->x1, &_fi->y1);
 
       _fi->ly = (f32)(_fi->baseline + _fi->y0);
       lx += (_fi->advance * SF);
@@ -269,7 +263,7 @@ int main()
       i32 kern;
       if (i < char_sz - 1 && text[i+1] != '\n')
       {
-        kern = stbtt_GetGlyphKernAdvance(&font_info, amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i]), amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i+1]));
+        kern = stbtt_GetGlyphKernAdvance(&(ArialFontState.font_info), amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i]), amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i+1]));
         lx += roundf(kern * SF);
       }
 
@@ -297,11 +291,12 @@ int main()
       }
       _fi->byte_offset = (i32)(_fi->lx + roundf(_fi->lsb * SF) + (_fi->ly * bitmap_width_from_text_info)) ;
       // store image data in bitmap
-      stbtt_MakeGlyphBitmap(&font_info, Bitmap + _fi->byte_offset, _fi->x1 - _fi->x0, _fi->y1 - _fi->y0, bitmap_width_from_text_info, SF, SF, amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i]));
+      stbtt_MakeGlyphBitmap(&(ArialFontState.font_info), Bitmap + _fi->byte_offset, _fi->x1 - _fi->x0, _fi->y1 - _fi->y0, bitmap_width_from_text_info, SF, SF, amr_GetGlyphIdFromCodepoint(latin_basic, GlyphIndexArray, text[i]));
       _fi++;
     }
 
     // ---------- prepare bitmap texture and buffer objects -----------
+    ////////////////////////////////// PREPARE TEXT FOR RENDERING ////////////
     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 
     f32 bmp_vertices[] = {
@@ -372,6 +367,7 @@ int main()
     State.ScreenCoords.tl = ScreenMidCoords - ScreenMidPx;
     State.ScreenCoords.br = ScreenMidCoords + ScreenMidPx;
 
+    // ////////////////////// DEFINE TEXT POSITION AND SCALE //////////////////
     // ====================== TEXT POSITIONING AND SCALING ======
     Vec2 text_dims = {((f32)bitmap_width_from_text_info)/2.0f, ((f32)bitmap_height_from_text_info)/2.0f};
     Vec2 text_scaled_dims = State.px_ratio * text_dims;
@@ -502,6 +498,7 @@ int main()
 #endif
 
         // =============== DRAW TEXT BITMAP RENDERING ===============
+        // ////////////////// RENDER TEXT BITMAP /////////////////////////////
         {
           Model = IdentityMat();
           Mat4 Scale = CreateScaleMat(InitVec4(text_scaled_dims.x, text_scaled_dims.y, 1, 0));