Allegro学习笔记八
http://wiki.allegro.cc/AllegroExamples 以上是英文例子站点。
by Shawn Hargreaves,allegro的作者
目录： 1 Allegro 例子
1.1 exhello
1.2 exmem
1.3 expat
1.4 expal
1.5 exflame
1.6 exbuf
1.7 exflip
1.8 exfixed
这个范例展示了如何使用fixed类型的数--32位有符号数据
--整数部分放在高16位，小数部分放在低16位。这个范例
同时也展示了使用allegro专有的allegro_message()来与
用户的交流--其中大部分技巧并不常用。(原文..但是我觉得
很有用，类似printf的格式输出)
#include <allegro.h>
int main(void)
{
/* declare three 32 bit (16.16) fixed point variables */
fixed x, y, z;
if (allegro_init() != 0)
return 1;
/* convert integers to fixed point like this */
x = itofix(10);
/* convert floating point to fixed point like this */
y = ftofix(3.14);
/* fixed point variables can be assigned, added, subtracted, negated,
* and compared just like integers, eg:
*/
z = x + y;
allegro_message("%f + %f = %f/n", fixtof(x), fixtof(y), fixtof(z));
/* you can't add integers or floating point to fixed point, though:
* z = x + 3;
* would give the wrong result.
*/
/* fixed point variables can be multiplied or divided by integers or
* floating point numbers, eg:
*/
z = y * 2;
allegro_message("%f * 2 = %f/n", fixtof(y), fixtof(z));
/* you can't multiply or divide two fixed point numbers, though:
* z = x * y;
* would give the wrong result. Use fixmul() and fixdiv() instead, eg:
*/
z = fixmul(x, y);
allegro_message("%f * %f = %f/n", fixtof(x), fixtof(y), fixtof(z));
/* fixed point trig and square root are also available, eg: */
z = fixsqrt(x);
allegro_message("fixsqrt(%f) = %f/n", fixtof(x), fixtof(z));
return 0;
}
END_OF_MAIN()
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小结八：
1、fixed类型，可以看作是扩展了的实数型，但是是定点数。
2、由于不涉及图像显示，所以不需要设置显示模式之类的。
3、x = itofix(10);y = ftofix(3.14);格式输出等等等等，这些还是参照帮助文档来吧...偶不是潭浩强教授: