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/*
Cg functions to decode and filter textures in Radiance (RGBE) high dynamic range format
sgg 2/15/02
http://www.graphics.cornell.edu/~bjw/rgbe.html
*/
#if 0
typedef float4 vec4;
typedef float3 vec3;
typedef float2 vec2;
typedef float real;
#define texRECT f4texRECT
#define texCUBE f4texCUBE
#else
typedef half4 vec4;
typedef half3 vec3;
typedef half2 vec2;
typedef half real;
#define texRECT h4texRECT
#define texCUBE h4texCUBE
#endif
struct fragin
{
float4 wpos : WPOS;
float3 tex0 : TEXCOORD0;
float3 tex1 : TEXCOORD1;
float4 col0 : COLOR0;
};
// Lookup in RGBE-encoded rectangle texture
vec3 texRECT_RGBE(uniform samplerRECT tex, float2 t)
{
vec4 rgbe = texRECT(tex, t);
real e = (rgbe[3] * 255) - 128;
return rgbe.xyz * exp2(e);
}
// Lookup in RGBE-encoded cube map texture
vec3 texCUBE_RGBE(uniform samplerCUBE tex, float3 t)
{
vec4 rgbe = texCUBE(tex, t);
real e = (rgbe[3] * 255) - 128;
return rgbe.xyz * exp2(e);
}
// Lookup in RGBE-encoded rectangle texture with filtering
vec3 texRECT_RGBE_Bilinear(uniform samplerRECT tex, half2 t)
{
float2 f = frac(t);
vec3 t0 = texRECT_RGBE(tex, t);
vec3 t1 = texRECT_RGBE(tex, t + half2(1,0) );
vec3 t2 = lerp(t0, t1, f[0]);
t0 = texRECT_RGBE(tex, t + half2(0,1) );
t1 = texRECT_RGBE(tex, t + half2(1,1) );
t0 = lerp(t0, t1, f[0]);
t0 = lerp(t2, t0, f[1]);
return t0;
}
// Lookup in cubemap encoded as two HILO cube maps
vec3 texCUBE_hilo(uniform samplerCUBE rg_tex : TEXUNIT0, uniform samplerCUBE b_tex : TEXUNIT1, float3 t)
{
vec3 c;
c.xy = texCUBE(rg_tex, t).xy;
c.z = texCUBE(b_tex, t).x;
// c = c * c;
return c;
}
// Lookup in rectangle texture encoded as two HILO cube maps
vec3 texRECT_hilo(uniform samplerRECT rg_tex : TEXUNIT0, uniform samplerRECT b_tex : TEXUNIT1, float2 t)
{
vec3 c;
c.xy = texRECT(rg_tex, t).xy;
c.z = texRECT(b_tex, t).x;
return c;
}
// bilinear lookup in float texture
vec4 texRECT_bilinear(uniform samplerRECT tex, half2 t)
{
float2 f = frac(t);
vec4 t0 = texRECT(tex, t);
vec4 t1 = texRECT(tex, t + half2(1,0) );
vec4 t2 = lerp(t0, t1, f[0]);
t0 = texRECT(tex, t + half2(0,1) );
t1 = texRECT(tex, t + half2(1,1) );
t0 = lerp(t0, t1, f[0]);
t0 = lerp(t2, t0, f[1]);
return t0;
}
// applying vignetting based on window coordinates
void vignette(inout float3 c, float4 wpos, const float2 win_bias, const float2 win_scale)
{
// convert window coord to [-1, 1] range
wpos.xy = (wpos.xy - win_bias) * win_scale;
// calculate distance from origin
float r = length(wpos.xy);
r = 1.0 - smoothstep(0.8, 1.5, r);
c = c * r;
}
// refraction function from Renderman spec
// I = incident direction, N = normal, eta = relative index of refraction
half3 my_refract(half3 I, half3 N, half eta)
{
half IdotN = dot(I,N);
half k = 1 - eta*eta*(1 - IdotN*IdotN);
return eta*I - (eta*IdotN + sqrt(k))*N;
}
// fresnel approximation
half my_fresnel(half3 I, half3 N, half power, half scale, half bias)
{
return bias + (pow(max(0.0, 1.0 - dot(I, N)), power) * scale);
}
// transform a direction vector by a 4x4 matrix
float3 transform_dir(float4x4 m, float3 v)
{
float3 o;
o.x = dot(v, m._11_12_13);
o.y = dot(v, m._21_22_23);
o.z = dot(v, m._31_32_33);
return o;
}
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