diff options
Diffstat (limited to 'src/mesa/tnl/t_vb_fog.c')
| -rw-r--r-- | src/mesa/tnl/t_vb_fog.c | 49 |
1 files changed, 42 insertions, 7 deletions
diff --git a/src/mesa/tnl/t_vb_fog.c b/src/mesa/tnl/t_vb_fog.c index 2adb8d18500..e7f740dfa3c 100644 --- a/src/mesa/tnl/t_vb_fog.c +++ b/src/mesa/tnl/t_vb_fog.c @@ -1,4 +1,4 @@ -/* $Id: t_vb_fog.c,v 1.2 2001/01/03 22:56:23 brianp Exp $ */ +/* $Id: t_vb_fog.c,v 1.3 2001/02/06 04:06:36 keithw Exp $ */ /* * Mesa 3-D graphics library @@ -49,10 +49,42 @@ struct fog_stage_data { #define FOG_STAGE_DATA(stage) ((struct fog_stage_data *)stage->private) +#define FOG_EXP_TABLE_SIZE 256 +#define FOG_MAX (5.0) +#define EXP_FOG_MAX .0006595 +#define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE) +static GLfloat exp_table[FOG_EXP_TABLE_SIZE]; +static GLfloat inited = 0; + +#if 1 +#define NEG_EXP( result, narg ) \ +do { \ + float f = (narg * (1.0/FOG_INCR)); \ + int k = (int) f; \ + if (k > FOG_EXP_TABLE_SIZE-2) \ + result = EXP_FOG_MAX; \ + else \ + result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]); \ +} while (0) +#else +#define NEG_EXP( result, narg ) \ +do { \ + result = exp(-narg); \ +} while (0) +#endif + + +static void init_static_data( void ) +{ + float f = 0; + int i = 0; + for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) { + exp_table[i] = exp(-f); + } + inited = 1; +} -/* Use lookup table & interpolation? - */ static void make_win_fog_coords( GLcontext *ctx, GLvector1f *out, const GLvector1f *in ) { @@ -76,15 +108,15 @@ static void make_win_fog_coords( GLcontext *ctx, GLvector1f *out, data[i] = (end - ABSF(*v)) * d; break; case GL_EXP: - d = -ctx->Fog.Density; + d = ctx->Fog.Density; for ( i = 0 ; i < n ; i++, STRIDE_F(v,stride)) - data[i] = exp( d*ABSF(*v) ); + NEG_EXP( data[i], d*ABSF(*v) ); break; case GL_EXP2: - d = -(ctx->Fog.Density*ctx->Fog.Density); + d = ctx->Fog.Density*ctx->Fog.Density; for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) { GLfloat z = *v; - data[i] = exp( d*z*z ); + NEG_EXP( data[i], d*z*z ); } break; default: @@ -173,6 +205,9 @@ static GLboolean alloc_fog_data( GLcontext *ctx, gl_vector1f_alloc( &store->fogcoord, 0, tnl->vb.Size, 32 ); gl_vector1f_init( &store->input, 0, 0 ); + if (!inited) + init_static_data(); + /* Now run the stage. */ stage->run = run_fog_stage; |