Move dither functions to a standalone header for use throughout softl…

…ight.
hamsham · Mar 20, 2022 · 26f663c · 26f663c
1 parent 3d9179d
commit 26f663c
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Showing 3 changed files with 124 additions and 41 deletions.
diff --git a/softlight/CMakeLists.txt b/softlight/CMakeLists.txt
@@ -132,6 +132,7 @@ set(SL_LIB_HEADERS
     include/softlight/SL_ColorYCoCg.hpp
     include/softlight/SL_Config.hpp
     include/softlight/SL_Context.hpp
+    include/softlight/SL_Dither.hpp
     include/softlight/SL_FontLoader.hpp
     include/softlight/SL_FragmentProcessor.hpp
     include/softlight/SL_Framebuffer.hpp

diff --git a/softlight/include/softlight/SL_Dither.hpp b/softlight/include/softlight/SL_Dither.hpp
@@ -0,0 +1,118 @@
+//
+// Created by hammy on 2022-03-17.
+//
+
+#ifndef SOFTLIGHT_DITHER_HPP
+#define SOFTLIGHT_DITHER_HPP
+
+#include "lightsky/setup/Api.h"
+
+#include "lightsky/math/scalar_utils.h"
+
+
+
+/*-----------------------------------------------------------------------------
+ * 2x2 Ordered Dithering
+-----------------------------------------------------------------------------*/
+inline LS_INLINE float sl_bayer_dither_2x2(const float color, const unsigned x, const unsigned y)
+{
+    constexpr unsigned bayerMatrix16[4] = {
+        0, 2,
+        3, 1
+    };
+    return ls::math::step(color, (float)bayerMatrix16[(x % 2u) + (y % 2u) * 2u] / 4.f);
+}
+
+
+
+template <unsigned numBits = 8>
+inline float sl_dither2(float c, const unsigned x, const unsigned y)
+{
+    const float paletteColor = c * (float)((1u << numBits)-1u);
+    const float bayer = paletteColor + sl_bayer_dither_2x2(c, x, y);
+    return ls::math::clamp(bayer/(float)((1u << numBits)-1u), 0.f, 1.f);
+}
+
+
+
+template <>
+inline float sl_dither2<1u>(float c, const unsigned x, const unsigned y)
+{
+    return 1.f-sl_bayer_dither_2x2(c, x, y);
+}
+
+
+
+/*-----------------------------------------------------------------------------
+ * 4x4 Ordered Dithering
+-----------------------------------------------------------------------------*/
+inline LS_INLINE float sl_bayer_dither_4x4(const float color, const unsigned x, const unsigned y)
+{
+    constexpr unsigned bayerMatrix16[16] = {
+        0,  8,  2,  10,
+        12, 4,  14, 6,
+        3,  11, 1,  9,
+        15, 7,  13, 5
+    };
+    return ls::math::step(color, (float)bayerMatrix16[(x % 4u) + (y % 4u) * 4u] / 16.f);
+}
+
+
+
+template <unsigned numBits = 8>
+inline float sl_dither4(float c, const unsigned x, const unsigned y)
+{
+    const float paletteColor = c * (float)((1u << numBits)-1u);
+    const float bayer = paletteColor + sl_bayer_dither_4x4(c, x, y);
+    return ls::math::clamp(bayer/(float)((1u << numBits)-1u), 0.f, 1.f);
+}
+
+
+
+template <>
+inline float sl_dither4<1u>(float c, const unsigned x, const unsigned y)
+{
+    return 1.f-sl_bayer_dither_4x4(c, x, y);
+}
+
+
+
+/*-----------------------------------------------------------------------------
+ * 8x8 Ordered Dithering
+-----------------------------------------------------------------------------*/
+inline LS_INLINE float sl_bayer_dither_8x8(const float color, const unsigned x, const unsigned y)
+{
+    constexpr unsigned bayerMatrix16[64] = {
+        0,  32, 8,  40, 2,  34, 10, 42,
+        48, 16, 56, 24, 50, 18, 58, 26,
+        12, 44, 4,  36, 14, 46, 6,  38,
+        60, 28, 52, 20, 62, 30, 54, 22,
+        3,  35, 11, 43, 1,  33, 9,  41,
+        51, 19, 59, 27, 49, 17, 57, 25,
+        15, 47, 7,  39, 13, 45, 5,  37,
+        63, 31, 55, 23, 61, 29, 53, 21
+    };
+    return ls::math::step(color, (float)bayerMatrix16[(x % 8u) + (y % 8u) * 8u] / 64.f);
+}
+
+
+
+template <unsigned numBits = 8>
+inline float sl_dither8(float c, const unsigned x, const unsigned y)
+{
+    const float paletteColor = c * (float)((1u << numBits)-1u);
+    const float bayer = paletteColor + sl_bayer_dither_8x8(c, x, y);
+    return ls::math::clamp(bayer/(float)((1u << numBits)-1u), 0.f, 1.f);
+}
+
+
+
+template <>
+inline float sl_dither8<1u>(float c, const unsigned x, const unsigned y)
+{
+    return 1.f-sl_bayer_dither_8x8(c, x, y);
+}
+
+
+
+#endif /* SOFTLIGHT_DITHER_HPP */
diff --git a/softlight/tests/sl_skybox_test.cpp b/softlight/tests/sl_skybox_test.cpp
@@ -14,10 +14,10 @@
 
 #include "softlight/SL_BoundingBox.hpp"
 #include "softlight/SL_Camera.hpp"
-#include "softlight/SL_ColorHSX.hpp"
 #include "softlight/SL_Context.hpp"
+#include "softlight/SL_Dither.hpp"
 #include "softlight/SL_ImgFile.hpp"
-#include "softlight/SL_ImgFilePPM.hpp"
+//#include "softlight/SL_ImgFilePPM.hpp"
 #include "softlight/SL_IndexBuffer.hpp"
 #include "softlight/SL_Framebuffer.hpp"
 #include "softlight/SL_KeySym.hpp"
@@ -101,42 +101,6 @@ SL_VertexShader sky_vert_shader()
 /*--------------------------------------
  * Fragment Shader
 --------------------------------------*/
-inline LS_INLINE float bayer_dither_4x4(const float c, const unsigned x, const unsigned y)
-{
-    constexpr unsigned bayerMatrix16[16] = {
-        0,  8,  2,  10,
-        12, 4,  14, 6,
-        3,  11, 1,  9,
-        15, 7,  13, 5
-    };
-    return math::step(c, ((float)bayerMatrix16[(x % 4u) + (y % 4u) * 4u] - 0.5f) / 16.f);
-}
-
-inline LS_INLINE float bayer_dither_8x8(const float c, const unsigned x, const unsigned y)
-{
-    constexpr unsigned bayerMatrix16[64] = {
-        0,  32, 8,  40, 2,  34, 10, 42,
-        48, 16, 56, 24, 50, 18, 58, 26,
-        12, 44, 4,  36, 14, 46, 6,  38,
-        60, 28, 52, 20, 62, 30, 54, 22,
-        3,  35, 11, 43, 1,  33, 9,  41,
-        51, 19, 59, 27, 49, 17, 57, 25,
-        15, 47, 7,  39, 13, 45, 5,  37,
-        63, 31, 55, 23, 61, 29, 53, 21
-    };
-    return math::step(c, ((float)bayerMatrix16[(x % 8u) + (y % 8u) * 8u] - 0.5f) / 64.f);
-}
-
-template <unsigned numBits = 8>
-inline float dither(float c, const unsigned x, const unsigned y)
-{
-    const float paletteColor = c * (float)((1u << numBits)-1u);
-    const float bayer = paletteColor + bayer_dither_4x4(c, x, y);
-    return bayer/(float)((1u << numBits)-1u);
-}
-
-
-
 bool _sky_frag_shader(SL_FragmentParam& fragParam)
 {
     const SkyUniforms* pUniforms = fragParam.pUniforms->as<SkyUniforms>();
@@ -148,9 +112,9 @@ bool _sky_frag_shader(SL_FragmentParam& fragParam)
 
     // output composition
     const math::vec4 ditheredColor{
-        dither<5>(albedof[0], fragParam.coord.x, fragParam.coord.y),
-        dither<6>(albedof[1], fragParam.coord.x, fragParam.coord.y),
-        dither<5>(albedof[2], fragParam.coord.x, fragParam.coord.y),
+        sl_dither2<5>(albedof[0], fragParam.coord.x, fragParam.coord.y),
+        sl_dither2<6>(albedof[1], fragParam.coord.x, fragParam.coord.y),
+        sl_dither2<5>(albedof[2], fragParam.coord.x, fragParam.coord.y),
         1.f
     };