Shader shadow_breakpoint_scale

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shadow_breakpoint_scale.mi
declare shader 
    color "shadow_breakpoint_scale" ( 
        color "color" default 1 1 1, 
        color "transparency" default .5 .5 .5, 
	scalar "breakpoint" default .5, 
	scalar "center" default .5, 
	scalar "extent" default 1 ) 
    version 1 
    apply shadow 
end declare 

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

shadow_breakpoint_scale_util.c
double miaux_shadow_breakpoint_scale ( 
    double color, double transparency, double breakpoint,  
    double center, double extent ) 
{ 
    double scaled_color =  
	miaux_fit(color, 0, 1, center - extent/2.0, center + extent/2.0); 
    if (transparency < breakpoint) 
	return miaux_fit(transparency, 0, breakpoint, 0, scaled_color); 
    else 
	return miaux_fit(transparency, breakpoint, 1, scaled_color, 1); 
} 
 
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 23:40:15