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deps/include/Box2D/Particle/b2Particle.cpp

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+/*
+* Copyright (c) 2013 Google, Inc.
+*
+* This software is provided 'as-is', without any express or implied
+* warranty.  In no event will the authors be held liable for any damages
+* arising from the use of this software.
+* Permission is granted to anyone to use this software for any purpose,
+* including commercial applications, and to alter it and redistribute it
+* freely, subject to the following restrictions:
+* 1. The origin of this software must not be misrepresented; you must not
+* claim that you wrote the original software. If you use this software
+* in a product, an acknowledgment in the product documentation would be
+* appreciated but is not required.
+* 2. Altered source versions must be plainly marked as such, and must not be
+* misrepresented as being the original software.
+* 3. This notice may not be removed or altered from any source distribution.
+*/
+#include <Box2D/Particle/b2Particle.h>
+#include <Box2D/Common/b2Draw.h>
+
+#define B2PARTICLECOLOR_BITS_PER_COMPONENT (sizeof(uint8) << 3)
+// Maximum value of a b2ParticleColor component.
+#define B2PARTICLECOLOR_MAX_VALUE \
+	((1U << B2PARTICLECOLOR_BITS_PER_COMPONENT) - 1)
+
+/// Number of bits used to store each b2ParticleColor component.
+const uint8 b2ParticleColor::k_bitsPerComponent =
+	B2PARTICLECOLOR_BITS_PER_COMPONENT;
+const float32 b2ParticleColor::k_maxValue = (float)B2PARTICLECOLOR_MAX_VALUE;
+const float32 b2ParticleColor::k_inverseMaxValue =
+	1.0f / (float)B2PARTICLECOLOR_MAX_VALUE;
+
+b2ParticleColor b2ParticleColor_zero(0, 0, 0, 0);
+
+b2ParticleColor::b2ParticleColor(const b2Color& color)
+{
+	Set(color);
+}
+
+b2Color b2ParticleColor::GetColor() const
+{
+	return b2Color(k_inverseMaxValue * r,
+				   k_inverseMaxValue * g,
+				   k_inverseMaxValue * b);
+}
+
+void b2ParticleColor::Set(const b2Color& color)
+{
+	Set((uint8)(k_maxValue * color.r),
+		(uint8)(k_maxValue * color.g),
+		(uint8)(k_maxValue * color.b),
+		B2PARTICLECOLOR_MAX_VALUE);
+}
+
+int32 b2CalculateParticleIterations(
+	float32 gravity, float32 radius, float32 timeStep)
+{
+	// In some situations you may want more particle iterations than this,
+	// but to avoid excessive cycle cost, don't recommend more than this.
+	const int32 B2_MAX_RECOMMENDED_PARTICLE_ITERATIONS = 8;
+	const float32 B2_RADIUS_THRESHOLD = 0.01f;
+	int32 iterations =
+		(int32) ceilf(b2Sqrt(gravity / (B2_RADIUS_THRESHOLD * radius)) * timeStep);
+	return b2Clamp(iterations, 1, B2_MAX_RECOMMENDED_PARTICLE_ITERATIONS);
+}