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Change fog-of-war blur to use a better filter.

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This was SVN commit r8889.
This commit is contained in:
Ykkrosh 2011-02-05 18:19:28 +00:00
parent bf3d5c75f0
commit aa1fcfd20c
2 changed files with 28 additions and 37 deletions
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63
source/graphics/LOSTexture.cpp
View File

@ -33,19 +33,19 @@
The LOS bitmap is computed with one value per map vertex, based on
CCmpRangeManager's visibility information.
The bitmap is then blurred using an NxN box filter (i.e. convolution
with (1 1 1; 1 1 1; 1 1 1) etc). To implement the blur efficiently without
using extra memory for a second copy of the bitmap, we generate the bitmap
with (N-1)/2 pixels of padding on each side, then the blur shifts the
image back into the corner.
The bitmap is then blurred using an NxN filter (in particular a
7-tap Binomial filter as an efficient integral approximation of a Gaussian).
To implement the blur efficiently without using extra memory for a second copy
of the bitmap, we generate the bitmap with (N-1)/2 pixels of padding on each side,
then the blur shifts the image back into the corner.
The blurred bitmap is then uploaded into a GL texture for use by the renderer.
*/
// Blur with a NxN box filter, where N = g_BlurSize must be an odd number.
static const size_t g_BlurSize = 5;
// Blur with a NxN filter, where N = g_BlurSize must be an odd number.
static const size_t g_BlurSize = 7;
CLOSTexture::CLOSTexture() :
m_Dirty(true), m_Texture(0), m_MapSize(0), m_TextureSize(0)
@ -200,25 +200,18 @@ void CLOSTexture::GenerateBitmap(ICmpRangeManager::CLosQuerier los, u8* losData,
for (size_t j = g_BlurSize/2; j < h + g_BlurSize/2; ++j)
{
u32 accum = 0; // sum of values in the sliding Nx1 window
// Initialise the filter window for the first output pixel
// (Start i at the first of the non-padding pixels, since the
// padding was set to 0)
for (size_t i = g_BlurSize/2; i < g_BlurSize-1; ++i)
accum += losData[i+j*rowSize];
// For each pixel, update the sliding window and store the average
// of the window's sum
for (size_t i = 0; i < w; ++i)
{
accum += losData[i+g_BlurSize-1+j*rowSize];
u8 old = losData[i+j*rowSize];
losData[i+j*rowSize] = accum / g_BlurSize;
accum -= old;
u8* d = &losData[i+j*rowSize];
*d = (
1*d[0] +
6*d[1] +
15*d[2] +
20*d[3] +
15*d[4] +
6*d[5] +
1*d[6]
) / 64;
}
}
@ -226,20 +219,18 @@ void CLOSTexture::GenerateBitmap(ICmpRangeManager::CLosQuerier los, u8* losData,
for (size_t i = 0; i < w; ++i)
{
u32 accum = 0;
for (size_t j = g_BlurSize/2; j < g_BlurSize-1; ++j)
accum += losData[i+j*rowSize];
for (size_t j = 0; j < h; ++j)
{
accum += losData[i+(j+g_BlurSize-1)*rowSize];
u8 old = losData[i+j*rowSize];
losData[i+j*rowSize] = accum / g_BlurSize;
accum -= old;
u8* d = &losData[i+j*rowSize];
*d = (
1*d[0*rowSize] +
6*d[1*rowSize] +
15*d[2*rowSize] +
20*d[3*rowSize] +
15*d[4*rowSize] +
6*d[5*rowSize] +
1*d[6*rowSize]
) / 64;
}
}
}

2
source/graphics/tests/test_LOSTexture.h
View File

@ -50,7 +50,7 @@ public:
// for (size_t i = 0; i < losData.size(); ++i)
// printf("%s %3d", i % (size_t)sqrt(losData.size()) ? "" : "\n", losData[i]);
TS_ASSERT_EQUALS(losData[0], 91);
TS_ASSERT_EQUALS(losData[0], 104);
}
void test_perf_DISABLED()