From 807daf323785c4a034a11b850dc6da7da2bbfe53 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 13 Sep 2020 11:09:12 +0300
Subject: [PATCH] Add pixmap bluring

---
 libs/pcg/include/psemek/pcg/blur.hpp | 11 ++++++
 libs/pcg/source/blur.cpp             | 55 ++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 libs/pcg/include/psemek/pcg/blur.hpp
 create mode 100644 libs/pcg/source/blur.cpp

diff --git a/libs/pcg/include/psemek/pcg/blur.hpp b/libs/pcg/include/psemek/pcg/blur.hpp
new file mode 100644
index 00000000..3121f518
--- /dev/null
+++ b/libs/pcg/include/psemek/pcg/blur.hpp
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <psemek/gfx/pixmap.hpp>
+#include <psemek/pcg/seamless.hpp>
+
+namespace psemek::pcg
+{
+
+	gfx::basic_pixmap<float> blur(gfx::basic_pixmap<float> const & p, int size, float sigma, seamless_tag);
+
+}
diff --git a/libs/pcg/source/blur.cpp b/libs/pcg/source/blur.cpp
new file mode 100644
index 00000000..ea1fe88d
--- /dev/null
+++ b/libs/pcg/source/blur.cpp
@@ -0,0 +1,55 @@
+#include <psemek/pcg/blur.hpp>
+
+#include <cmath>
+#include <vector>
+
+namespace psemek::pcg
+{
+
+	static std::vector<float> gauss_coeffs(int size, float sigma)
+	{
+		std::vector<float> res(2 * size + 1);
+		float sum = 0.f;
+		for (int i = -size; i <= size; ++i)
+		{
+			float x = (i / sigma);
+			res[i + size] = std::exp(- x * x);
+			sum += res[i + size];
+		}
+		for (auto & c : res)
+			c /= sum;
+		return res;
+	}
+
+	gfx::basic_pixmap<float> blur(gfx::basic_pixmap<float> const & p, int size, float sigma, seamless_tag)
+	{
+		gfx::basic_pixmap<float> res({p.width(), p.height()}, 0.f);
+
+		auto c = gauss_coeffs(size, sigma);
+
+		for (int y = 0; y < p.height(); ++y)
+		{
+			for (int x = 0; x < p.width(); ++x)
+			{
+				for (int j = - size; j <= size; ++j)
+				{
+					for (int i = - size; i <= size; ++i)
+					{
+						int ix = (x + i);
+						while (ix < 0) ix += p.width();
+						if (ix >= p.width()) ix = ix % p.width();
+
+						int iy = (y + j);
+						while (iy < 0) iy += p.height();
+						if (iy >= p.height()) iy = iy % p.height();
+
+						res(x, y) += p(ix, iy) * c[i + size] * c[j + size];
+					}
+				}
+			}
+		}
+
+		return res;
+	}
+
+}