153 lines
4.2 KiB
C++
153 lines
4.2 KiB
C++
//========= Copyright Valve Corporation, All rights reserved. ============//
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//
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// Purpose:
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//
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// $NoKeywords: $
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//
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//=============================================================================//
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#include "cbase.h"
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#include "particledraw.h"
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#include "materialsystem/imesh.h"
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// memdbgon must be the last include file in a .cpp file!!!
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#include "tier0/memdbgon.h"
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//-----------------------------------------------------------------------------
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// Sees if the tracer is behind the camera or should be culled
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//-----------------------------------------------------------------------------
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static bool ClipTracer( const Vector &start, const Vector &delta, Vector &clippedStart, Vector &clippedDelta )
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{
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// dist1 = start dot forward - origin dot forward
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// dist2 = (start + delta ) dot forward - origin dot forward
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// in camera space this is -start[2] since origin = 0 and vecForward = (0, 0, -1)
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float dist1 = -start[2];
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float dist2 = dist1 - delta[2];
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// Clipped, skip this tracer
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if ( dist1 <= 0 && dist2 <= 0 )
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return true;
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clippedStart = start;
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clippedDelta = delta;
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// Needs to be clipped
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if ( dist1 <= 0 || dist2 <= 0 )
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{
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float fraction = dist2 - dist1;
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// Too close to clipping plane
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if ( fraction < 1e-3 && fraction > -1e-3 )
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return true;
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fraction = -dist1 / fraction;
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if ( dist1 <= 0 )
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{
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VectorMA( start, fraction, delta, clippedStart );
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}
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else
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{
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VectorMultiply( delta, fraction, clippedDelta );
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}
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}
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return false;
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}
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//-----------------------------------------------------------------------------
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// Computes the four verts to draw the tracer with
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//-----------------------------------------------------------------------------
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bool Tracer_ComputeVerts( const Vector &start, const Vector &delta, float width, Vector *pVerts )
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{
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Vector clippedStart, clippedDelta;
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// Clip the tracer
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if ( ClipTracer( start, delta, clippedStart, clippedDelta ) )
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return false;
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// Figure out direction in camera space of the normal
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Vector normal;
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CrossProduct( clippedDelta, clippedStart, normal );
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// don't draw if they are parallel
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float sqLength = DotProduct( normal, normal );
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if (sqLength < 1e-3)
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return false;
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// Resize the normal to be appropriate based on the width
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VectorScale( normal, 0.5f * width / sqrt(sqLength), normal );
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VectorSubtract( clippedStart, normal, pVerts[0] );
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VectorAdd( clippedStart, normal, pVerts[1] );
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VectorAdd( pVerts[0], clippedDelta, pVerts[2] );
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VectorAdd( pVerts[1], clippedDelta, pVerts[3] );
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return true;
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}
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void Tracer_Draw( CMeshBuilder *pMeshBuilder, Vector& start, Vector& delta, float width, float* color, float startV, float endV )
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{
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// Clip the tracer
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Vector verts[4];
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if (!Tracer_ComputeVerts( start, delta, width, verts ))
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return;
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// NOTE: Gotta get the winding right so it's not backface culled
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// (we need to turn of backface culling for these bad boys)
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pMeshBuilder->Position3f( verts[0].x, verts[0].y, verts[0].z );
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pMeshBuilder->TexCoord2f( 0, 0.0f, startV );
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if (color)
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{
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pMeshBuilder->Color4fv( color );
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}
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else
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{
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pMeshBuilder->Color4ub( 255, 255, 255, 255 );
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}
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pMeshBuilder->AdvanceVertex();
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pMeshBuilder->Position3f( verts[1].x, verts[1].y, verts[1].z );
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pMeshBuilder->TexCoord2f( 0, 1.0f, startV );
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if (color)
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{
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pMeshBuilder->Color4fv( color );
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}
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else
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{
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pMeshBuilder->Color4ub( 255, 255, 255, 255 );
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}
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pMeshBuilder->AdvanceVertex();
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pMeshBuilder->Position3f( verts[3].x, verts[3].y, verts[3].z );
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pMeshBuilder->TexCoord2f( 0, 1.0f, endV );
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if (color)
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pMeshBuilder->Color4fv( color );
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else
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pMeshBuilder->Color4ub( 255, 255, 255, 255 );
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pMeshBuilder->AdvanceVertex();
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pMeshBuilder->Position3f( verts[2].x, verts[2].y, verts[2].z );
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pMeshBuilder->TexCoord2f( 0, 0.0f, endV );
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if (color)
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pMeshBuilder->Color4fv( color );
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else
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pMeshBuilder->Color4ub( 255, 255, 255, 255 );
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pMeshBuilder->AdvanceVertex();
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}
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//-----------------------------------------------------------------------------
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// draw a tracer.
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//-----------------------------------------------------------------------------
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void Tracer_Draw( ParticleDraw* pDraw, Vector& start, Vector& delta, float width, float* color, float startV, float endV )
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{
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if( !pDraw->GetMeshBuilder() )
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return;
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Tracer_Draw( pDraw->GetMeshBuilder(), start, delta, width, color, startV, endV );
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}
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