feat: #102 Update length of trail

skylicht-lab · Sep 16, 2020 · 5709290 · 5709290
1 parent 11b8b4a
commit 5709290
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Showing 2 changed files with 50 additions and 2 deletions.
diff --git a/Projects/Skylicht/Components/Source/ParticleSystem/Particles/CParticleTrail.cpp b/Projects/Skylicht/Components/Source/ParticleSystem/Particles/CParticleTrail.cpp
@@ -36,8 +36,10 @@ namespace Skylicht
 			m_width(0.1f),
 			m_alpha(1.0f),
 			m_trailCount(0),
-			m_maxSegmentCount(10)
+			m_maxSegmentCount(0)
 		{
+			setLength(2.0f);
+
 			group->setCallback(this);
 
 			m_meshBuffer = new CMeshBuffer<video::S3DVertex>(getVideoDriver()->getVertexDescriptor(EVT_STANDARD), EIT_32BIT);
@@ -61,6 +63,12 @@ namespace Skylicht
 				m_meshBuffer->drop();
 		}
 
+		void CParticleTrail::setLength(float l)
+		{
+			m_maxSegmentCount = (int)(l / m_segmentLength + 1.0f);
+			m_length = l;
+		}
+
 		void CParticleTrail::update(CCamera *camera)
 		{
 			if (m_group == NULL)
@@ -99,6 +107,8 @@ namespace Skylicht
 					endSeg = (int)(numSeg - m_maxSegmentCount + 1);
 
 				u32 numSegDraw = 0;
+				float currentLength = 0.0f;
+
 				for (int i = numSeg; i >= endSeg; i--)
 				{
 					core::vector3df pos1;
@@ -127,10 +137,20 @@ namespace Skylicht
 						thickness = p1.Width;
 					}
 
-					// line direction
+					// direction
 					core::vector3df direction = pos1 - pos2;
+
+					// length
+					currentLength = currentLength + direction.getLength();
+
 					direction.normalize();
 
+					if (currentLength > m_length)
+					{
+						float cutLength = currentLength - m_length;
+						pos2 = pos2 + cutLength * direction;
+					}
+
 					// look
 					core::vector3df lookdir = pos1 - campos;
 					if (lookdir.getLength() < 0.2f)
@@ -191,6 +211,10 @@ namespace Skylicht
 
 						totalSegDraw++;
 						numSegDraw++;
+
+						// skip
+						if (currentLength >= m_length)
+							break;
 					}
 				}
 			}

diff --git a/Projects/Skylicht/Components/Source/ParticleSystem/Particles/CParticleTrail.h b/Projects/Skylicht/Components/Source/ParticleSystem/Particles/CParticleTrail.h
@@ -71,6 +71,8 @@ namespace Skylicht
 
 			float m_width;
 
+			float m_length;
+
 			float m_alpha;
 
 			int m_trailCount;
@@ -96,6 +98,28 @@ namespace Skylicht
 			{
 				return m_meshBuffer;
 			}
+
+			inline void setWidth(float f)
+			{
+				m_width = f;
+			}
+
+			inline float getWidth()
+			{
+				return m_width;
+			}
+
+			inline void setSegmentLength(float f)
+			{
+				m_segmentLength = f;
+			}
+
+			inline float getSegmentLength()
+			{
+				return m_segmentLength;
+			}
+
+			void setLength(float l);
 		};
 	}
 }