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Add triangle filter sampling.

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This commit is contained in:
castano 2007-12-06 10:13:01 +00:00
parent 12f2456e90
commit d3240ff992
2 changed files with 33 additions and 5 deletions
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34
src/nvimage/Filter.cpp
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@ -104,10 +104,13 @@ Filter::Filter(float width) : m_width(width)
{
}
float Filter::sample(float x, float scale, int samples) const
float Filter::sampleDelta(float x, float scale) const
{
// return evaluate(x * scale);
return evaluate((x + 0.5f)* scale);
}
float Filter::sampleBox(float x, float scale, int samples) const
{
float sum = 0;
float isamples = 1.0f / float(samples);
@ -121,6 +124,29 @@ float Filter::sample(float x, float scale, int samples) const
return sum * isamples;
}
float Filter::sampleTriangle(float x, float scale, int samples) const
{
float sum = 0;
float isamples = 1.0f / float(samples);
for(int s = 0; s < samples; s++)
{
float offset = (2 * float(s) + 1.0f) * isamples;
float p = (x + offset - 0.5f) * scale;
float value = evaluate(p);
float weight = offset;
if (weight > 1.0f) weight = 2.0f - weight;
sum += value * weight;
}
return 2 * sum * isamples;
}
BoxFilter::BoxFilter() : Filter(0.5f) {}
BoxFilter::BoxFilter(float width) : Filter(width) {}
@ -257,7 +283,7 @@ Kernel1::Kernel1(const Filter & f, int iscale, int samples/*= 32*/)
float total = 0.0f;
for (int i = 0; i < m_windowSize; i++)
{
const float sample = f.sample(i - offset, scale, samples);
const float sample = f.sampleBox(i - offset, scale, samples);
m_data[i] = sample;
total += sample;
}
@ -539,7 +565,7 @@ PolyphaseKernel::PolyphaseKernel(const Filter & f, uint srcLength, uint dstLengt
float total = 0.0f;
for (int j = 0; j < m_windowSize; j++)
{
const float sample = f.sample(left + j - center, scale, samples);
const float sample = f.sampleBox(left + j - center, scale, samples);
m_data[i * m_windowSize + j] = sample;
total += sample;

4
src/nvimage/Filter.h
View File

@ -18,7 +18,9 @@ namespace nv
NVIMAGE_API virtual ~Filter();
NVIMAGE_API float width() const { return m_width; }
NVIMAGE_API float sample(float x, float scale, int samples) const;
NVIMAGE_API float sampleDelta(float x, float scale) const;
NVIMAGE_API float sampleBox(float x, float scale, int samples) const;
NVIMAGE_API float sampleTriangle(float x, float scale, int samples) const;
virtual float evaluate(float x) const = 0;