Author: Carlos Lopez <genet...@gmail.com>
Date: Thu Sep 6 20:35:50 2012 +0200
etl::surface: normal sample functions assumes that the surface's content is a
value that is not "cooked" (premultiplied for colors). Add proper functions to
sample a point when the surface is already "cooked"
---
ETL/ETL/_surface.h | 257 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 257 insertions(+), 0 deletions(-)
diff --git a/ETL/ETL/_surface.h b/ETL/ETL/_surface.h
index 06c2109..a1f6d6b 100644
--- a/ETL/ETL/_surface.h
+++ b/ETL/ETL/_surface.h
@@ -398,6 +398,32 @@ public:
return cooker_.uncook(ret);
}
+ //! Linear sample for already "cooked" surfaces
+ value_type linear_sample_cooked(const float x, const float y)const
+ {
+ int u(floor_to_int(x)), v(floor_to_int(y));
+ float a, b;
+ static const float epsilon(1.0e-6);
+
+ if(x<0.0f)u=0,a=0.0f;
+ else if(x>w_-1)u=w_-1,a=0.0f;
+ else a=x-u;
+
+ if(y<0.0f)v=0,b=0.0f;
+ else if(y>h_-1)v=h_-1,b=0.0f;
+ else b=y-v;
+
+ const float
+ c(1.0f-a), d(1.0f-b),
+ e(a*d),f(c*b),g(a*b);
+
+ accumulator_type ret((*this)[v][u]*(c*d));
+ if(e>=epsilon)ret+=(*this)[v][u+1]*e;
+ if(f>=epsilon)ret+=(*this)[v+1][u]*f;
+ if(g>=epsilon)ret+=(*this)[v+1][u+1]*g;
+ return ret;
+ }
+
//! Cosine sample
value_type cosine_sample(const float x, const float y)const
{
@@ -428,6 +454,36 @@ public:
return cooker_.uncook(ret);
}
+ //! Cosine sample for already "cooked" surfaces
+ value_type cosine_sample_cooked(const float x, const float y)const
+ {
+ int u(floor_to_int(x)), v(floor_to_int(y));
+ float a, b;
+ static const float epsilon(1.0e-6);
+
+ if(x<0.0f)u=0,a=0.0f;
+ else if(x>w_-1)u=w_-1,a=0.0f;
+ else a=x-u;
+
+ if(y<0.0f)v=0,b=0.0f;
+ else if(y>h_-1)v=h_-1,b=0.0f;
+ else b=y-v;
+
+ a=(1.0f-cos(a*3.1415927f))*0.5f;
+ b=(1.0f-cos(b*3.1415927f))*0.5f;
+
+ const float
+ c(1.0f-a), d(1.0f-b),
+ e(a*d),f(c*b),g(a*b);
+
+ accumulator_type ret((*this)[v][u]*(c*d));
+ if(e>=epsilon)ret+=(*this)[v][u+1]*e;
+ if(f>=epsilon)ret+=(*this)[v+1][u]*f;
+ if(g>=epsilon)ret+=(*this)[v+1][u+1]*g;
+
+ return ret;
+ }
+
//! Cubic sample
value_type cubic_sample(float x, float y)const
{
@@ -511,6 +567,53 @@ public:
#endif
}
+ //! Cubic sample for already "cooked" surfaces
+ value_type cubic_sample_cooked(float x, float y)const
+ {
+#define f(j,i) (((*this)[j][i]))
+ //Using catmull rom interpolation because it doesn't blur at all
+ //bezier curve with intermediate ctrl pts: 0.5/3(p(i+1) -
p(i-1)) and similar
+ accumulator_type xfa [4];
+
+ //precalculate indices (all clamped) and offset
+ const int xi = x > 0 ? (x < w_ ? (int)floor(x) : w_-1) : 0;
+ const int xa[] =
{std::max(0,xi-1),xi,std::min(w_-1,xi+1),std::min(w_-1,xi+2)};
+
+ const int yi = y > 0 ? (y < h_ ? (int)floor(y) : h_-1) : 0;
+ const int ya[] =
{std::max(0,yi-1),yi,std::min(h_-1,yi+1),std::min(h_-1,yi+2)};
+
+ const float xf = x-xi;
+ const float yf = y-yi;
+
+ //figure polynomials for each point
+ const float txf[] =
+ {
+ 0.5*xf*(xf*(xf*(-1) + 2) - 1), //-t + 2t^2 -t^3
+ 0.5*(xf*(xf*(3*xf - 5)) + 2), //2 - 5t^2 + 3t^3
+ 0.5*xf*(xf*(-3*xf + 4) + 1), //t + 4t^2 - 3t^3
+ 0.5*xf*xf*(xf-1) //-t^2
+ t^3
+ };
+
+ const float tyf[] =
+ {
+ 0.5*yf*(yf*(yf*(-1) + 2) - 1), //-t + 2t^2 -t^3
+ 0.5*(yf*(yf*(3*yf - 5)) + 2), //2 - 5t^2 + 3t^3
+ 0.5*yf*(yf*(-3*yf + 4) + 1), //t + 4t^2 - 3t^3
+ 0.5*yf*yf*(yf-1) //-t^2
+ t^3
+ };
+
+ //evaluate polynomial for each row
+ for(int i = 0; i < 4; ++i)
+ {
+ xfa[i] = f(ya[i],xa[0])*txf[0] + f(ya[i],xa[1])*txf[1]
+ f(ya[i],xa[2])*txf[2] + f(ya[i],xa[3])*txf[3];
+ }
+
+ //return the cumulative column evaluation
+ return xfa[0]*tyf[0] + xfa[1]*tyf[1] + xfa[2]*tyf[2] +
xfa[3]*tyf[3];
+#undef f
+ }
+
+ //! Rectangle sample
value_type sample_rect(float x0,float y0,float x1,float y1) const
{
const surface &s = *this;
@@ -577,6 +680,74 @@ public:
return cooker_.uncook(acum);
}
+ //! Rectangle sample for already "cooked" surfaces
+ value_type sample_rect_cooked(float x0,float y0,float x1,float y1)
const
+ {
+ const surface &s = *this;
+
+ //assumes it's clamped to the boundary of the image
+ //force min max relationship for x0,x1 and y0,y1
+ if(x0 > x1) std::swap(x0,x1);
+ if(y0 > y1) std::swap(y0,y1);
+
+ //local variable madness
+ //all things that want to inter-operate should provide a
default value constructor for = 0
+ accumulator_type acum = 0;
+ int xi=0,yi=0;
+
+ int xib=(int)floor(x0),
+ xie=(int)floor(x1);
+
+ int yib=(int)floor(y0),
+ yie=(int)floor(y1);
+
+ //the weight for the pixel should remain the same...
+ float weight = (y1-y0)*(x1-x0);
+ assert(weight != 0);
+
+ float ylast = y0, xlastb = x0;
+ const_pen pen_ = s.get_pen(xib,yib);
+
+ for(yi = yib; yi < yie; ylast = ++yi, pen_.inc_y())
+ {
+ const float yweight = yi+1 - ylast;
+
+ float xlast = xlastb;
+ for(xi = xib; xi < xie; xlast = ++xi, pen_.inc_x())
+ {
+ const float w = yweight*(xi+1 - xlast);
+ acum += pen_.get_value()*w;
+ }
+
+ //post... with next being fractional...
+ const float w = yweight*(x1 - xlast);
+ acum += pen_.get_value()*w;
+
+ pen_.dec_x(xie-xib);
+ }
+
+ //post in y direction... must have all x...
+ {
+ const float yweight = y1 - ylast;
+
+ float xlast = xlastb;
+ for(xi = xib; xi < xie; xlast = ++xi)
+ {
+ const float w = yweight*(xi+1 - xlast);
+
+ acum += pen_.get_value()*w;
+ }
+
+ //post... with next being fractional...
+ const float w = yweight*(x1 - xlast);
+ acum += pen_.get_value()*w;
+ }
+
+ acum *= 1/weight;
+ return acum;
+ }
+
+ //! Rectangle sample clipped
value_type sample_rect_clip(float x0,float y0,float x1,float y1)
const
{
const surface &s = *this;
@@ -661,6 +832,92 @@ public:
acum *= 1/weight;
return cooker_.uncook(acum);
}
+
+ //! Rectangle sample clipped for already "cooked" surfaces
+ value_type sample_rect_clip_cooked(float x0,float y0,float
x1,float y1) const
+ {
+ const surface &s = *this;
+
+ //assumes it's clamped to the boundary of the image
+ //force min max relationship for x0,x1 and y0,y1
+ if(x0 > x1) std::swap(x0,x1);
+ if(y0 > y1) std::swap(y0,y1);
+
+ //local variable madness
+ //all things that want to inter-operate should provide a
default value constructor for = 0
+ accumulator_type acum = 0;
+ int xi=0,yi=0;
+
+ int xib=(int)floor(x0),
+ xie=(int)floor(x1);
+
+ int yib=(int)floor(y0),
+ yie=(int)floor(y1);
+
+ //the weight for the pixel should remain the same...
+ float weight = (y1-y0)*(x1-x0);
+
+ assert(weight != 0);
+
+ //clip to the input region
+ if(x0 >= s.get_w() || x1 <= 0) return acum;
+ if(y0 >= s.get_h() || y1 <= 0) return acum;
+
+ if(x0 < 0) { x0 = 0; xib = 0; }
+ if(x1 >= s.get_w())
+ {
+ x1 = s.get_w(); //want to be just below the last
pixel...
+ xie = s.get_w()-1;
+ }
+
+ if(y0 < 0) { y0 = 0; yib = 0; }
+ if(y1 >= s.get_h())
+ {
+ y1 = s.get_h(); //want to be just below the last
pixel...
+ yie = s.get_h()-1;
+ }
+
+ float ylast = y0, xlastb = x0;
+ const_pen pen = s.get_pen(xib,yib);
+
+ for(yi = yib; yi < yie; ylast = ++yi, pen.inc_y())
+ {
+ const float yweight = yi+1 - ylast;
+
+ float xlast = xlastb;
+ for(xi = xib; xi < xie; xlast = ++xi, pen.inc_x())
+ {
+ const float w = yweight*(xi+1 - xlast);
+ acum += pen.get_value()*w;
+ }
+
+ //post... with next being fractional...
+ const float w = yweight*(x1 - xlast);
+ acum += pen.get_value()*w;
+
+ pen.dec_x(xie-xib);
+ }
+
+ //post in y direction... must have all x...
+ {
+ const float yweight = y1 - ylast;
+
+ float xlast = xlastb;
+ for(xi = xib; xi < xie; xlast = ++xi)
+ {
+ const float w = yweight*(xi+1 - xlast);
+
+ acum += pen.get_value()*w;
+ }
+
+ //post... with next being fractional...
+ const float w = yweight*(x1 - xlast);
+ acum += pen.get_value()*w;
+ }
+
+ acum *= 1/weight;
+ return acum;
+ }
};
_ETL_END_NAMESPACE
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