Shader shadow_continuous

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shadow_continuous.mi
declare shader 
    color "shadow_continuous" ( 
        color "color" default 1 1 1, 
        color "transparency" default .5 .5 .5, 
        scalar "expansion" default 1 ) 
    version 1 
    apply shadow 
end declare 

shadow_continuous.c
#include "shader.h" 
#include "miaux.h" 
 
DLLEXPORT 
int shadow_continuous_version(void) { return 1; } 
 
struct shadow_continuous { 
    miColor color; 
    miColor transparency; 
    miScalar expansion; 
}; 
 
DLLEXPORT 
miBoolean shadow_continuous (  
    miColor *result, 
    miState *state, 
    struct shadow_continuous *params  ) 
{ 
    miColor *color = mi_eval_color(&params->color); 
    miColor *transparency = mi_eval_color(&params->transparency); 
    miScalar expansion = *mi_eval_scalar(&params->expansion); 
 
    result->r *= miaux_shadow_continuous (color->r, transparency->r, expansion ); 
    result->g *= miaux_shadow_continuous (color->g, transparency->g, expansion ); 
    result->b *= miaux_shadow_continuous (color->b, transparency->b, expansion ); 
 
    return miaux_all_channels_equal(result, 0.0) ? miFALSE : miTRUE; 
} 

shadow_continuous_util.c
double miaux_shadow_continuous ( 
    double color, double transparency, double expansion ) 
{ 
    return transparency  
	+ miaux_fit(transparency, 
		    0, 1,  
		    expansion * transparency * (color - transparency), 0); 
} 
 
double miaux_fit( 
    double v, double oldmin, double oldmax, double newmin, double newmax)     
{ 
    return newmin + ((v - oldmin) / (oldmax - oldmin)) * (newmax - newmin); 
} 
 
miBoolean miaux_all_channels_equal(miColor *c, miScalar v) 
{ 
    if (c->r == v && c->g == v && c->b == v && c->a == v) 
	return miTRUE; 
    else 
	return miFALSE; 
} 

22 April 2008 23:40:16