[Mesa-dev] [PATCH 6/6] mesa: remove DEG2RAD macro

[Jose Fonseca]

On 24/02/15 23:30, Brian Paul wrote:
> ---
>   src/mesa/main/imports.h  | 8 --------
>   src/mesa/main/light.c    | 2 +-
>   src/mesa/math/m_matrix.c | 4 ++--
>   3 files changed, 3 insertions(+), 11 deletions(-)
>
> diff --git a/src/mesa/main/imports.h b/src/mesa/main/imports.h
> index 356f0e1..d886427 100644
> --- a/src/mesa/main/imports.h
> +++ b/src/mesa/main/imports.h
> @@ -79,14 +79,6 @@ typedef union { GLfloat f; GLint i; GLuint u; } fi_type;
>
>
>
> -/**********************************************************************
> - * Math macros
> - */
> -
> -/* Degrees to radians conversion: */
> -#define DEG2RAD (M_PI/180.0)
> -
> -
>   #if defined(_MSC_VER)
>   #if _MSC_VER < 1800  /* Not req'd on VS2013 and above */
>   #define strtoll(p, e, b) _strtoi64(p, e, b)
> diff --git a/src/mesa/main/light.c b/src/mesa/main/light.c
> index c4d3a53..4021dbe 100644
> --- a/src/mesa/main/light.c
> +++ b/src/mesa/main/light.c
> @@ -156,7 +156,7 @@ _mesa_light(struct gl_context *ctx, GLuint lnum, GLenum pname, const GLfloat *pa
>            return;
>         FLUSH_VERTICES(ctx, _NEW_LIGHT);
>         light->SpotCutoff = params[0];
> -      light->_CosCutoff = (GLfloat) (cos(light->SpotCutoff * DEG2RAD));
> +      light->_CosCutoff = (GLfloat) (cos(light->SpotCutoff * M_PI / 180.0));

It might be worthwhile to add parenthesis  around M_PI / 180.0.

I'm not sure the compiler will fold, due to C operator precedence, and 
the fact that floating point operations when not being associative:

$ cat deg2rad.c
#include <math.h>


double deg2rad(double angle) {
	return angle * M_PI / 180.0;
}
$ gcc -O3 -s -S -o -  deg2rad.c
	.file	"deg2rad.c"
	.section	.text.unlikely,"ax", at progbits
.LCOLDB2:
	.text
.LHOTB2:
	.p2align 4,,15
	.globl	deg2rad
	.type	deg2rad, @function
deg2rad:
.LFB3:
	.cfi_startproc
	mulsd	.LC0(%rip), %xmm0
	divsd	.LC1(%rip), %xmm0   <===================================
	ret
	.cfi_endproc
.LFE3:
	.size	deg2rad, .-deg2rad
	.section	.text.unlikely
.LCOLDE2:
	.text
.LHOTE2:
	.section	.rodata.cst8,"aM", at progbits,8
	.align 8
.LC0:
	.long	1413754136
	.long	1074340347
	.align 8
.LC1:
	.long	0
	.long	1080459264
	.ident	"GCC: (Debian 4.9.1-19) 4.9.1"
	.section	.note.GNU-stack,"", at progbits



Otherwise series looks good to me.



Jose


>         if (light->_CosCutoff < 0)
>            light->_CosCutoff = 0;
>         if (light->SpotCutoff != 180.0F)
> diff --git a/src/mesa/math/m_matrix.c b/src/mesa/math/m_matrix.c
> index 9d51021..0475a7a 100644
> --- a/src/mesa/math/m_matrix.c
> +++ b/src/mesa/math/m_matrix.c
> @@ -799,8 +799,8 @@ _math_matrix_rotate( GLmatrix *mat,
>      GLfloat m[16];
>      GLboolean optimized;
>
> -   s = (GLfloat) sin( angle * DEG2RAD );
> -   c = (GLfloat) cos( angle * DEG2RAD );
> +   s = (GLfloat) sin( angle * M_PI / 180.0 );
> +   c = (GLfloat) cos( angle * M_PI / 180.0 );
>
>      memcpy(m, Identity, sizeof(GLfloat)*16);
>      optimized = GL_FALSE;
>