Squashed 'external/parallel-rdp/parallel-rdp-standalone/' content from commit 3f59f61f2c

git-subtree-dir: external/parallel-rdp/parallel-rdp-standalone
git-subtree-split: 3f59f61f2c1c56424356003041df5e4a10612049

parallel-rdp/shaders/noise.h

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+/* Copyright (c) 2020 Themaister
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef NOISE_H_
+#define NOISE_H_
+
+u16 seeded_noise = U16_C(0);
+
+// From: https://www.shadertoy.com/view/XlXcW4 with slight modifications.
+void reseed_noise(uint x, uint y, uint primitive_offset)
+{
+	const uint NOISE_PRIME = 1103515245u;
+	uvec3 seed = uvec3(x, y, primitive_offset);
+	seed = ((seed >> 8u) ^ seed.yzx) * NOISE_PRIME;
+	seed = ((seed >> 8u) ^ seed.yzx) * NOISE_PRIME;
+	seed = ((seed >> 8u) ^ seed.yzx) * NOISE_PRIME;
+	seeded_noise = u16(seed.x >> 16u);
+}
+
+i16 noise_get_combiner()
+{
+	return i16(((seeded_noise & U16_C(7u)) << U16_C(6u)) | U16_C(0x20u));
+}
+
+int noise_get_dither_alpha()
+{
+	return int(seeded_noise & U16_C(7u));
+}
+
+int noise_get_dither_color()
+{
+	// 3 bits of noise for RGB separately.
+	return int(seeded_noise & U16_C(0x1ff));
+}
+
+u8 noise_get_blend_threshold()
+{
+	return u8(seeded_noise & U16_C(0xffu));
+}
+
+uvec3 noise_get_full_gamma_dither()
+{
+	uint seed = seeded_noise;
+	return uvec3(seed & 0x3f, (seed >> 6u) & 0x3f, ((seed >> 9u) & 0x38) | (seed & 7u));
+}
+
+uvec3 noise_get_partial_gamma_dither()
+{
+	return (uvec3(seeded_noise) >> uvec3(0, 1, 2)) & 1u;
+}
+
+#endif