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Enable cleanTransparent filter for mipmapping and improve its' algori…
…thm (#11145)
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sfan5 committed Apr 20, 2021
1 parent 90a7bd6 commit 1da73418cd2ea0e03e8289f54a47dededcf8b331
@@ -504,18 +504,17 @@ bilinear_filter (Bilinear filtering) bool false
trilinear_filter (Trilinear filtering) bool false

# Filtered textures can blend RGB values with fully-transparent neighbors,
# which PNG optimizers usually discard, sometimes resulting in a dark or
# light edge to transparent textures. Apply this filter to clean that up
# at texture load time.
# which PNG optimizers usually discard, often resulting in dark or
# light edges to transparent textures. Apply a filter to clean that up
# at texture load time. This is automatically enabled if mipmapping is enabled.
texture_clean_transparent (Clean transparent textures) bool false

# When using bilinear/trilinear/anisotropic filters, low-resolution textures
# can be blurred, so automatically upscale them with nearest-neighbor
# interpolation to preserve crisp pixels. This sets the minimum texture size
# for the upscaled textures; higher values look sharper, but require more
# memory. Powers of 2 are recommended. Setting this higher than 1 may not
# have a visible effect unless bilinear/trilinear/anisotropic filtering is
# enabled.
# memory. Powers of 2 are recommended. This setting is ONLY applies if
# bilinear/trilinear/anisotropic filtering is enabled.
# This is also used as the base node texture size for world-aligned
# texture autoscaling.
texture_min_size (Minimum texture size) int 64
@@ -102,7 +102,7 @@ video::ITexture *guiScalingResizeCached(video::IVideoDriver *driver,
if (!g_settings->getBool("gui_scaling_filter_txr2img"))
return src;
srcimg = driver->createImageFromData(src->getColorFormat(),
src->getSize(), src->lock(), false);
src->getSize(), src->lock(video::ETLM_READ_ONLY), false);
src->unlock();
g_imgCache[origname] = srcimg;
}
@@ -19,63 +19,134 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include "imagefilters.h"
#include "util/numeric.h"
#include <cmath>
#include <cassert>
#include <vector>

// Simple 2D bitmap class with just the functionality needed here
class Bitmap {
u32 linesize, lines;
std::vector<u8> data;

static inline u32 bytepos(u32 index) { return index >> 3; }
static inline u8 bitpos(u32 index) { return index & 7; }

public:
Bitmap(u32 width, u32 height) : linesize(width), lines(height),
data(bytepos(width * height) + 1) {}

inline bool get(u32 x, u32 y) const {
u32 index = y * linesize + x;
return data[bytepos(index)] & (1 << bitpos(index));
}

inline void set(u32 x, u32 y) {
u32 index = y * linesize + x;
data[bytepos(index)] |= 1 << bitpos(index);
}

inline bool all() const {
for (u32 i = 0; i < data.size() - 1; i++) {
if (data[i] != 0xff)
return false;
}
// last byte not entirely filled
for (u8 i = 0; i < bitpos(linesize * lines); i++) {
bool value_of_bit = data.back() & (1 << i);
if (!value_of_bit)
return false;
}
return true;
}

inline void copy(Bitmap &to) const {
assert(to.linesize == linesize && to.lines == lines);
to.data = data;
}
};

/* Fill in RGB values for transparent pixels, to correct for odd colors
* appearing at borders when blending. This is because many PNG optimizers
* like to discard RGB values of transparent pixels, but when blending then
* with non-transparent neighbors, their RGB values will shpw up nonetheless.
* with non-transparent neighbors, their RGB values will show up nonetheless.
*
* This function modifies the original image in-place.
*
* Parameter "threshold" is the alpha level below which pixels are considered
* transparent. Should be 127 for 3d where alpha is threshold, but 0 for
* 2d where alpha is blended.
* transparent. Should be 127 when the texture is used with ALPHA_CHANNEL_REF,
* 0 when alpha blending is used.
*/
void imageCleanTransparent(video::IImage *src, u32 threshold)
{
core::dimension2d<u32> dim = src->getDimension();

// Walk each pixel looking for fully transparent ones.
Bitmap bitmap(dim.Width, dim.Height);

// First pass: Mark all opaque pixels
// Note: loop y around x for better cache locality.
for (u32 ctry = 0; ctry < dim.Height; ctry++)
for (u32 ctrx = 0; ctrx < dim.Width; ctrx++) {
if (src->getPixel(ctrx, ctry).getAlpha() > threshold)
bitmap.set(ctrx, ctry);
}

// Exit early if all pixels opaque
if (bitmap.all())
return;

Bitmap newmap = bitmap;

// Then repeatedly look for transparent pixels, filling them in until
// we're finished (capped at 50 iterations).
for (u32 iter = 0; iter < 50; iter++) {

// Ignore opaque pixels.
irr::video::SColor c = src->getPixel(ctrx, ctry);
if (c.getAlpha() > threshold)
for (u32 ctry = 0; ctry < dim.Height; ctry++)
for (u32 ctrx = 0; ctrx < dim.Width; ctrx++) {
// Skip pixels we have already processed
if (bitmap.get(ctrx, ctry))
continue;

// Sample size and total weighted r, g, b values.
video::SColor c = src->getPixel(ctrx, ctry);

// Sample size and total weighted r, g, b values
u32 ss = 0, sr = 0, sg = 0, sb = 0;

// Walk each neighbor pixel (clipped to image bounds).
// Walk each neighbor pixel (clipped to image bounds)
for (u32 sy = (ctry < 1) ? 0 : (ctry - 1);
sy <= (ctry + 1) && sy < dim.Height; sy++)
for (u32 sx = (ctrx < 1) ? 0 : (ctrx - 1);
sx <= (ctrx + 1) && sx < dim.Width; sx++) {

// Ignore transparent pixels.
irr::video::SColor d = src->getPixel(sx, sy);
if (d.getAlpha() <= threshold)
// Ignore pixels we haven't processed
if (!bitmap.get(sx, sy))
continue;

// Add RGB values weighted by alpha.
u32 a = d.getAlpha();

// Add RGB values weighted by alpha IF the pixel is opaque, otherwise
// use full weight since we want to propagate colors.
video::SColor d = src->getPixel(sx, sy);
u32 a = d.getAlpha() <= threshold ? 255 : d.getAlpha();
ss += a;
sr += a * d.getRed();
sg += a * d.getGreen();
sb += a * d.getBlue();
}

// If we found any neighbor RGB data, set pixel to average
// weighted by alpha.
// Set pixel to average weighted by alpha
if (ss > 0) {
c.setRed(sr / ss);
c.setGreen(sg / ss);
c.setBlue(sb / ss);
src->setPixel(ctrx, ctry, c);
newmap.set(ctrx, ctry);
}
}

if (newmap.all())
return;

// Apply changes to bitmap for next run. This is done so we don't introduce
// a bias in color propagation in the direction pixels are processed.
newmap.copy(bitmap);

}
}

/* Scale a region of an image into another image, using nearest-neighbor with
@@ -23,13 +23,13 @@ with this program; if not, write to the Free Software Foundation, Inc.,
/* Fill in RGB values for transparent pixels, to correct for odd colors
* appearing at borders when blending. This is because many PNG optimizers
* like to discard RGB values of transparent pixels, but when blending then
* with non-transparent neighbors, their RGB values will shpw up nonetheless.
* with non-transparent neighbors, their RGB values will show up nonetheless.
*
* This function modifies the original image in-place.
*
* Parameter "threshold" is the alpha level below which pixels are considered
* transparent. Should be 127 for 3d where alpha is threshold, but 0 for
* 2d where alpha is blended.
* transparent. Should be 127 when the texture is used with ALPHA_CHANNEL_REF,
* 0 when alpha blending is used.
*/
void imageCleanTransparent(video::IImage *src, u32 threshold);

@@ -491,7 +491,8 @@ video::ITexture *Minimap::getMinimapTexture()
// Want to use texture source, to : 1 find texture, 2 cache it
video::ITexture* texture = m_tsrc->getTexture(data->mode.texture);
video::IImage* image = driver->createImageFromData(
texture->getColorFormat(), texture->getSize(), texture->lock(), true, false);
texture->getColorFormat(), texture->getSize(),
texture->lock(video::ETLM_READ_ONLY), true, false);
texture->unlock();

auto dim = image->getDimension();
@@ -427,6 +427,7 @@ class TextureSource : public IWritableTextureSource
std::unordered_map<std::string, Palette> m_palettes;

// Cached settings needed for making textures from meshes
bool m_setting_mipmap;
bool m_setting_trilinear_filter;
bool m_setting_bilinear_filter;
};
@@ -447,6 +448,7 @@ TextureSource::TextureSource()
// Cache some settings
// Note: Since this is only done once, the game must be restarted
// for these settings to take effect
m_setting_mipmap = g_settings->getBool("mip_map");
m_setting_trilinear_filter = g_settings->getBool("trilinear_filter");
m_setting_bilinear_filter = g_settings->getBool("bilinear_filter");
}
@@ -667,7 +669,7 @@ video::ITexture* TextureSource::getTexture(const std::string &name, u32 *id)
video::ITexture* TextureSource::getTextureForMesh(const std::string &name, u32 *id)
{
static thread_local bool filter_needed =
g_settings->getBool("texture_clean_transparent") ||
g_settings->getBool("texture_clean_transparent") || m_setting_mipmap ||
((m_setting_trilinear_filter || m_setting_bilinear_filter) &&
g_settings->getS32("texture_min_size") > 1);
// Avoid duplicating texture if it won't actually change
@@ -1636,8 +1638,8 @@ bool TextureSource::generateImagePart(std::string part_of_name,
return false;
}

// Apply the "clean transparent" filter, if configured.
if (g_settings->getBool("texture_clean_transparent"))
// Apply the "clean transparent" filter, if needed
if (m_setting_mipmap || g_settings->getBool("texture_clean_transparent"))
imageCleanTransparent(baseimg, 127);

/* Upscale textures to user's requested minimum size. This is a trick to make

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