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/****************************************************************************
* Copyright (C) 2014-2015 Intel Corporation. All Rights Reserved.
*
* 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 (including the next
* paragraph) 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.
*
* @file clip.cpp
*
* @brief Implementation for clipping
*
******************************************************************************/
#include <assert.h>
#include "common/os.h"
#include "core/clip.h"
// Temp storage used by the clipper
THREAD simdvertex tlsTempVertices[7];
#if USE_SIMD16_FRONTEND
THREAD simd16vertex tlsTempVertices_simd16[7];
#endif
float ComputeInterpFactor(float boundaryCoord0, float boundaryCoord1)
{
return (boundaryCoord0 / (boundaryCoord0 - boundaryCoord1));
}
template<SWR_CLIPCODES ClippingPlane>
inline void intersect(
int s, // index to first edge vertex v0 in pInPts.
int p, // index to second edge vertex v1 in pInPts.
const float *pInPts, // array of all the input positions.
const float *pInAttribs, // array of all attributes for all vertex. All the attributes for each vertex is contiguous.
int numInAttribs, // number of attributes per vertex.
int i, // output index.
float *pOutPts, // array of output positions. We'll write our new intersection point at i*4.
float *pOutAttribs) // array of output attributes. We'll write our new attributes at i*numInAttribs.
{
float t;
// Find the parameter of the intersection.
// t = (v1.w - v1.x) / ((v2.x - v1.x) - (v2.w - v1.w)) for x = w (RIGHT) plane, etc.
const float *v1 = &pInPts[s*4];
const float *v2 = &pInPts[p*4];
switch (ClippingPlane)
{
case FRUSTUM_LEFT: t = ComputeInterpFactor(v1[3] + v1[0], v2[3] + v2[0]); break;
case FRUSTUM_RIGHT: t = ComputeInterpFactor(v1[3] - v1[0], v2[3] - v2[0]); break;
case FRUSTUM_TOP: t = ComputeInterpFactor(v1[3] + v1[1], v2[3] + v2[1]); break;
case FRUSTUM_BOTTOM: t = ComputeInterpFactor(v1[3] - v1[1], v2[3] - v2[1]); break;
case FRUSTUM_NEAR: t = ComputeInterpFactor(v1[2], v2[2]); break;
case FRUSTUM_FAR: t = ComputeInterpFactor(v1[3] - v1[2], v2[3] - v2[2]); break;
default: SWR_INVALID("invalid clipping plane: %d", ClippingPlane);
};
const float *a1 = &pInAttribs[s*numInAttribs];
const float *a2 = &pInAttribs[p*numInAttribs];
float *pOutP = &pOutPts[i*4];
float *pOutA = &pOutAttribs[i*numInAttribs];
// Interpolate new position.
for(int j = 0; j < 4; ++j)
{
pOutP[j] = v1[j] + (v2[j]-v1[j])*t;
}
// Interpolate Attributes
for(int attr = 0; attr < numInAttribs; ++attr)
{
pOutA[attr] = a1[attr] + (a2[attr]-a1[attr])*t;
}
}
// Checks whether vertex v lies inside clipping plane
// in homogenous coords check -w < {x,y,z} < w;
//
template<SWR_CLIPCODES ClippingPlane>
inline int inside(const float v[4])
{
switch (ClippingPlane)
{
case FRUSTUM_LEFT : return (v[0]>=-v[3]);
case FRUSTUM_RIGHT : return (v[0]<= v[3]);
case FRUSTUM_TOP : return (v[1]>=-v[3]);
case FRUSTUM_BOTTOM : return (v[1]<= v[3]);
case FRUSTUM_NEAR : return (v[2]>=0.0f);
case FRUSTUM_FAR : return (v[2]<= v[3]);
default:
SWR_INVALID("invalid clipping plane: %d", ClippingPlane);
return 0;
}
}
// Clips a polygon in homogenous coordinates to a particular clipping plane.
// Takes in vertices of the polygon (InPts) and the clipping plane
// Puts the vertices of the clipped polygon in OutPts
// Returns number of points in clipped polygon
//
template<SWR_CLIPCODES ClippingPlane>
int ClipTriToPlane( const float *pInPts, int numInPts,
const float *pInAttribs, int numInAttribs,
float *pOutPts, float *pOutAttribs)
{
int i=0; // index number of OutPts, # of vertices in OutPts = i div 4;
for (int j = 0; j < numInPts; ++j)
{
int s = j;
int p = (j + 1) % numInPts;
int s_in = inside<ClippingPlane>(&pInPts[s*4]);
int p_in = inside<ClippingPlane>(&pInPts[p*4]);
// test if vertex is to be added to output vertices
if (s_in != p_in) // edge crosses clipping plane
{
// find point of intersection
intersect<ClippingPlane>(s, p, pInPts, pInAttribs, numInAttribs, i, pOutPts, pOutAttribs);
i++;
}
if (p_in) // 2nd vertex is inside clipping volume, add it to output
{
// Copy 2nd vertex position of edge over to output.
for(int k = 0; k < 4; ++k)
{
pOutPts[i*4 + k] = pInPts[p*4 + k];
}
// Copy 2nd vertex attributes of edge over to output.
for(int attr = 0; attr < numInAttribs; ++attr)
{
pOutAttribs[i*numInAttribs+attr] = pInAttribs[p*numInAttribs+attr];
}
i++;
}
// edge does not cross clipping plane and vertex outside clipping volume
// => do not add vertex
}
return i;
}
void ClipTriangles(DRAW_CONTEXT *pDC, PA_STATE& pa, uint32_t workerId, simdvector prims[], uint32_t primMask, simdscalari primId)
{
SWR_CONTEXT *pContext = pDC->pContext;
AR_BEGIN(FEClipTriangles, pDC->drawId);
Clipper<3> clipper(workerId, pDC);
clipper.ExecuteStage(pa, prims, primMask, primId);
AR_END(FEClipTriangles, 1);
}
void ClipLines(DRAW_CONTEXT *pDC, PA_STATE& pa, uint32_t workerId, simdvector prims[], uint32_t primMask, simdscalari primId)
{
SWR_CONTEXT *pContext = pDC->pContext;
AR_BEGIN(FEClipLines, pDC->drawId);
Clipper<2> clipper(workerId, pDC);
clipper.ExecuteStage(pa, prims, primMask, primId);
AR_END(FEClipLines, 1);
}
void ClipPoints(DRAW_CONTEXT *pDC, PA_STATE& pa, uint32_t workerId, simdvector prims[], uint32_t primMask, simdscalari primId)
{
SWR_CONTEXT *pContext = pDC->pContext;
AR_BEGIN(FEClipPoints, pDC->drawId);
Clipper<1> clipper(workerId, pDC);
clipper.ExecuteStage(pa, prims, primMask, primId);
AR_END(FEClipPoints, 1);
}
#if USE_SIMD16_FRONTEND
void SIMDCALL ClipTriangles_simd16(DRAW_CONTEXT *pDC, PA_STATE& pa, uint32_t workerId, simd16vector prims[], uint32_t primMask, simd16scalari primId)
{
SWR_CONTEXT *pContext = pDC->pContext;
AR_BEGIN(FEClipTriangles, pDC->drawId);
enum { VERTS_PER_PRIM = 3 };
Clipper<VERTS_PER_PRIM> clipper(workerId, pDC);
pa.useAlternateOffset = false;
clipper.ExecuteStage(pa, prims, primMask, primId);
AR_END(FEClipTriangles, 1);
}
void SIMDCALL ClipLines_simd16(DRAW_CONTEXT *pDC, PA_STATE& pa, uint32_t workerId, simd16vector prims[], uint32_t primMask, simd16scalari primId)
{
SWR_CONTEXT *pContext = pDC->pContext;
AR_BEGIN(FEClipLines, pDC->drawId);
enum { VERTS_PER_PRIM = 2 };
Clipper<VERTS_PER_PRIM> clipper(workerId, pDC);
pa.useAlternateOffset = false;
clipper.ExecuteStage(pa, prims, primMask, primId);
AR_END(FEClipLines, 1);
}
void SIMDCALL ClipPoints_simd16(DRAW_CONTEXT *pDC, PA_STATE& pa, uint32_t workerId, simd16vector prims[], uint32_t primMask, simd16scalari primId)
{
SWR_CONTEXT *pContext = pDC->pContext;
AR_BEGIN(FEClipPoints, pDC->drawId);
enum { VERTS_PER_PRIM = 1 };
Clipper<VERTS_PER_PRIM> clipper(workerId, pDC);
pa.useAlternateOffset = false;
clipper.ExecuteStage(pa, prims, primMask, primId);
AR_END(FEClipPoints, 1);
}
#endif
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