wined3d: Reimplement wined3d_ftoa().

The current implementation is not precise enough when the FPU is in REAL4
mode, which also happens to be the mode d3d9 sets by default. Doing the same
thing with integer math is a huge pain, so just replace the decimal separator
instead.

dlls/wined3d/utils.c

@@ -3806,51 +3806,18 @@ const char *wined3d_debug_location(DWORD location)
     return buf[0] ? wine_dbg_sprintf("%s", &buf[3]) : "0";
 }
 
-/* This should be equivalent to using the %.8e format specifier, but always
- * using '.' as decimal separator. This doesn't handle +/-INF or NAN, since
- * the GLSL and ARB parsers wouldn't be able to handle those anyway. */
+/* Print a floating point value with the %.8e format specifier, always using
+ * '.' as decimal separator. */
 void wined3d_ftoa(float value, char *s)
 {
-    int x, frac, exponent;
-    const char *sign = "";
-    double d;
+    int idx = 1;
 
-    d = value;
     if (copysignf(1.0f, value) < 0.0f)
-    {
-        d = -d;
-        sign = "-";
-    }
+        ++idx;
 
-    if (d == 0.0f)
-    {
-        x = 0;
-        frac = 0;
-        exponent = 0;
-    }
-    else
-    {
-        double t, diff;
-
-        exponent = floorf(log10f(d));
-        d /= pow(10.0, exponent);
-
-        x = d;
-        t = (d - x) * 100000000;
-        frac = t;
-        diff = t - frac;
-
-        if ((diff > 0.5) || (diff == 0.5 && (frac & 1)))
-        {
-            if (++frac >= 100000000)
-            {
-                frac = 0;
-                ++x;
-            }
-        }
-    }
-
-    sprintf(s, "%s%d.%08de%+03d", sign, x, frac, exponent);
+    sprintf(s, "%.8e", value);
+    if (isfinite(value))
+        s[idx] = '.';
 }
 
 void wined3d_release_dc(HWND window, HDC dc)