font: add draw_float

src/demo/font.cpp

@@ -4,6 +4,8 @@
 #include "demo/ta_parameter_presets.hpp"
 #include "demo/texture.hpp"
 
+#include "printf/unparse.h"
+
 namespace font {
 
   static inline vec2 transform_glyph_texture(const face& face, const vec2& t, int char_code)
@@ -70,6 +72,40 @@ namespace font {
                 base_color);
   }
 
+  static inline int format_float(char * s, float num)
+  {
+    int offset = 0;
+    bool negative = num < 0;
+    if (negative) {
+      s[offset++] = '-';
+      num = -num;
+    }
+    int32_t whole = num;
+    offset += unparse_base10_unsigned(&s[offset], whole, 0, 0);
+    s[offset++] = '.';
+    int32_t fraction = (int32_t)((num - (float)whole) * 1000.0);
+    if (fraction < 0)
+      fraction = -fraction;
+    offset += unparse_base10_unsigned(&s[offset], fraction, 3, '0');
+    return offset;
+  }
+
+  void face::draw_float(ta_parameter_writer& writer,
+                        const vec3& p,
+                        float num,
+                        uint32_t base_color,
+                        int length) const
+  {
+    char s[20];
+    int offset = format_float(s, num);
+    s[offset] = 0;
+    float x = p.x;
+    if (offset < length) {
+      x += hori_advance * (length - offset);
+    }
+    draw_string(writer, {x, p.y, p.z}, s, base_color);
+  }
+
   const face ter_u12n = {
     .texture_size = tsp_instruction_word::texture_u_size::from_int(128)
                   | tsp_instruction_word::texture_v_size::from_int(64),

src/demo/font.hpp

@@ -22,6 +22,26 @@ namespace font {
                     const vec3& p,
                     int c,
                     uint32_t base_color) const;
+
+    inline void draw_string(ta_parameter_writer& writer,
+                            const vec3& p,
+                            const char * s,
+                            uint32_t base_color) const
+    {
+      const uint8_t * u8 = (const uint8_t *)s;
+      float x = p.x;
+      while (*u8) {
+        int c = *u8++;
+        draw_glyph(writer, {x, p.y, p.z}, c, base_color);
+        x += hori_advance;
+      }
+    }
+
+    void draw_float(ta_parameter_writer& writer,
+                    const vec3& p,
+                    float num,
+                    uint32_t base_color,
+                    int length = 0) const;
   };
 
   extern const face ter_u12n;

src/demo/graphics.cpp

@@ -96,6 +96,8 @@ namespace graphics {
   {
     font::ter_u12n.global(writer);
     font::ter_u12n.draw_glyph(writer, vec3(10, 10, 10), 'a', 0xffffffff);
+    font::ter_u12n.draw_float(writer, vec3(10, 22, 10), 1.234, 0xffffffff, 7);
+    font::ter_u12n.draw_float(writer, vec3(10, 34, 10), -50.234, 0xffffffff, 7);
 
     writer.append<ta_global_parameter::end_of_list>() =
       ta_global_parameter::end_of_list(para_control::para_type::end_of_list);