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/******************************************************************************
Plush Version 1.2
clip.c
3D Frustum Clipping
Copyright (c) 1996-2000, Justin Frankel
******************************************************************************/
#include "plush.h"
#define NUM_CLIP_PLANES 5
typedef struct
{
pl_Vertex newVertices[8];
double Shades[8];
double MappingU[8];
double MappingV[8];
double eMappingU[8];
double eMappingV[8];
} _clipInfo;
static _clipInfo m_cl[2];
static double m_clipPlanes[NUM_CLIP_PLANES][4];
static pl_Cam *m_cam;
static pl_sInt32 m_cx, m_cy;
static double m_fov;
static double m_adj_asp;
static void _FindNormal(double x2, double x3,
double y2, double y3,
double zv,
double *res);
/* Returns: 0 if nothing gets in, 1 or 2 if pout1 & pout2 get in */
static pl_uInt _ClipToPlane(pl_uInt numVerts, double *plane);
void plClipSetFrustum(pl_Cam *cam) {
m_adj_asp = 1.0 / cam->AspectRatio;
m_fov = plMin(plMax(cam->Fov,1.0),179.0);
m_fov = (1.0/tan(m_fov*(PL_PI/360.0)))*(double) (cam->ClipRight-cam->ClipLeft);
m_cx = cam->CenterX<<20;
m_cy = cam->CenterY<<20;
m_cam = cam;
memset(m_clipPlanes,0,sizeof(m_clipPlanes));
/* Back */
m_clipPlanes[0][2] = -1.0;
m_clipPlanes[0][3] = -cam->ClipBack;
/* Left */
m_clipPlanes[1][3] = 0.00000001;
if (cam->ClipLeft == cam->CenterX) {
m_clipPlanes[1][0] = 1.0;
}
else _FindNormal(-100,-100,
100, -100,
m_fov*-100.0/(cam->ClipLeft-cam->CenterX),
m_clipPlanes[1]);
if (cam->ClipLeft > cam->CenterX) {
m_clipPlanes[1][0] = -m_clipPlanes[1][0];
m_clipPlanes[1][1] = -m_clipPlanes[1][1];
m_clipPlanes[1][2] = -m_clipPlanes[1][2];
}
/* Right */
m_clipPlanes[2][3] = 0.00000001;
if (cam->ClipRight == cam->CenterX) {
m_clipPlanes[2][0] = -1.0;
}
else _FindNormal(100,100,
-100, 100,
m_fov*100.0/(cam->ClipRight-cam->CenterX),
m_clipPlanes[2]);
if (cam->ClipRight < cam->CenterX) {
m_clipPlanes[2][0] = -m_clipPlanes[2][0];
m_clipPlanes[2][1] = -m_clipPlanes[2][1];
m_clipPlanes[2][2] = -m_clipPlanes[2][2];
}
/* Top */
m_clipPlanes[3][3] = 0.00000001;
if (cam->ClipTop == cam->CenterY) {
m_clipPlanes[3][1] = -1.0;
} else _FindNormal(100, -100,
100, 100,
m_fov*m_adj_asp*100.0/(cam->CenterY-cam->ClipTop),
m_clipPlanes[3]);
if (cam->ClipTop > cam->CenterY) {
m_clipPlanes[3][0] = -m_clipPlanes[3][0];
m_clipPlanes[3][1] = -m_clipPlanes[3][1];
m_clipPlanes[3][2] = -m_clipPlanes[3][2];
}
/* Bottom */
m_clipPlanes[4][3] = 0.00000001;
if (cam->ClipBottom == cam->CenterY) {
m_clipPlanes[4][1] = 1.0;
} else _FindNormal(-100, 100,
-100, -100,
m_fov*m_adj_asp*-100.0/(cam->CenterY-cam->ClipBottom),
m_clipPlanes[4]);
if (cam->ClipBottom < cam->CenterY) {
m_clipPlanes[4][0] = -m_clipPlanes[4][0];
m_clipPlanes[4][1] = -m_clipPlanes[4][1];
m_clipPlanes[4][2] = -m_clipPlanes[4][2];
}
}
void plClipRenderFace(pl_Face *face) {
pl_uInt k, a, w, numVerts, q;
double tmp, tmp2;
pl_Face newface;
for (a = 0; a < 3; a ++) {
m_cl[0].newVertices[a] = *(face->Vertices[a]);
m_cl[0].Shades[a] = face->Shades[a];
m_cl[0].MappingU[a] = face->MappingU[a];
m_cl[0].MappingV[a] = face->MappingV[a];
m_cl[0].eMappingU[a] = face->eMappingU[a];
m_cl[0].eMappingV[a] = face->eMappingV[a];
}
numVerts = 3;
q = 0;
a = (m_clipPlanes[0][3] < 0.0 ? 0 : 1);
while (a < NUM_CLIP_PLANES && numVerts > 2)
{
numVerts = _ClipToPlane(numVerts, m_clipPlanes[a]);
memcpy(&m_cl[0],&m_cl[1],sizeof(m_cl)/2);
a++;
}
if (numVerts > 2) {
memcpy(&newface,face,sizeof(pl_Face));
for (k = 2; k < numVerts; k ++) {
newface.fShade = plMax(0,plMin(face->fShade,1));
for (a = 0; a < 3; a ++) {
if (a == 0) w = 0;
else w = a+(k-2);
newface.Vertices[a] = m_cl[0].newVertices+w;
newface.Shades[a] = (pl_Float) m_cl[0].Shades[w];
newface.MappingU[a] = (pl_sInt32)m_cl[0].MappingU[w];
newface.MappingV[a] = (pl_sInt32)m_cl[0].MappingV[w];
newface.eMappingU[a] = (pl_sInt32)m_cl[0].eMappingU[w];
newface.eMappingV[a] = (pl_sInt32)m_cl[0].eMappingV[w];
newface.Scrz[a] = 1.0f/newface.Vertices[a]->xformedz;
tmp2 = m_fov * newface.Scrz[a];
tmp = tmp2*newface.Vertices[a]->xformedx;
tmp2 *= newface.Vertices[a]->xformedy;
newface.Scrx[a] = m_cx + ((pl_sInt32)((tmp*(float) (1<<20))));
newface.Scry[a] = m_cy - ((pl_sInt32)((tmp2*m_adj_asp*(float) (1<<20))));
}
newface.Material->_PutFace(m_cam,&newface);
plRender_TriStats[3] ++;
}
plRender_TriStats[2] ++;
}
}
pl_sInt plClipNeeded(pl_Face *face) {
double dr,dl,db,dt;
double f;
dr = (m_cam->ClipRight-m_cam->CenterX);
dl = (m_cam->ClipLeft-m_cam->CenterX);
db = (m_cam->ClipBottom-m_cam->CenterY);
dt = (m_cam->ClipTop-m_cam->CenterY);
f = m_fov*m_adj_asp;
return ((m_cam->ClipBack <= 0.0 ||
face->Vertices[0]->xformedz <= m_cam->ClipBack ||
face->Vertices[1]->xformedz <= m_cam->ClipBack ||
face->Vertices[2]->xformedz <= m_cam->ClipBack) &&
(face->Vertices[0]->xformedz >= 0 ||
face->Vertices[1]->xformedz >= 0 ||
face->Vertices[2]->xformedz >= 0) &&
(face->Vertices[0]->xformedx*m_fov<=dr*face->Vertices[0]->xformedz ||
face->Vertices[1]->xformedx*m_fov<=dr*face->Vertices[1]->xformedz ||
face->Vertices[2]->xformedx*m_fov<=dr*face->Vertices[2]->xformedz) &&
(face->Vertices[0]->xformedx*m_fov>=dl*face->Vertices[0]->xformedz ||
face->Vertices[1]->xformedx*m_fov>=dl*face->Vertices[1]->xformedz ||
face->Vertices[2]->xformedx*m_fov>=dl*face->Vertices[2]->xformedz) &&
(face->Vertices[0]->xformedy*f<=db*face->Vertices[0]->xformedz ||
face->Vertices[1]->xformedy*f<=db*face->Vertices[1]->xformedz ||
face->Vertices[2]->xformedy*f<=db*face->Vertices[2]->xformedz) &&
(face->Vertices[0]->xformedy*f>=dt*face->Vertices[0]->xformedz ||
face->Vertices[1]->xformedy*f>=dt*face->Vertices[1]->xformedz ||
face->Vertices[2]->xformedy*f>=dt*face->Vertices[2]->xformedz));
}
static void _FindNormal(double x2, double x3,double y2, double y3,
double zv, double *res) {
res[0] = zv*(y2-y3);
res[1] = zv*(x3-x2);
res[2] = x2*y3 - y2*x3;
}
/* Returns: 0 if nothing gets in, 1 or 2 if pout1 & pout2 get in */
static pl_uInt _ClipToPlane(pl_uInt numVerts, double *plane)
{
pl_uInt i, nextvert, curin, nextin;
double curdot, nextdot, scale;
pl_uInt invert, outvert;
invert = 0;
outvert = 0;
curdot = m_cl[0].newVertices[0].xformedx*plane[0] +
m_cl[0].newVertices[0].xformedy*plane[1] +
m_cl[0].newVertices[0].xformedz*plane[2];
curin = (curdot >= plane[3]);
for (i=0 ; i < numVerts; i++) {
nextvert = (i + 1) % numVerts;
if (curin) {
m_cl[1].Shades[outvert] = m_cl[0].Shades[invert];
m_cl[1].MappingU[outvert] = m_cl[0].MappingU[invert];
m_cl[1].MappingV[outvert] = m_cl[0].MappingV[invert];
m_cl[1].eMappingU[outvert] = m_cl[0].eMappingU[invert];
m_cl[1].eMappingV[outvert] = m_cl[0].eMappingV[invert];
m_cl[1].newVertices[outvert++] = m_cl[0].newVertices[invert];
}
nextdot = m_cl[0].newVertices[nextvert].xformedx*plane[0] +
m_cl[0].newVertices[nextvert].xformedy*plane[1] +
m_cl[0].newVertices[nextvert].xformedz*plane[2];
nextin = (nextdot >= plane[3]);
if (curin != nextin) {
scale = (plane[3] - curdot) / (nextdot - curdot);
m_cl[1].newVertices[outvert].xformedx = (pl_Float) (m_cl[0].newVertices[invert].xformedx +
(m_cl[0].newVertices[nextvert].xformedx - m_cl[0].newVertices[invert].xformedx)
* scale);
m_cl[1].newVertices[outvert].xformedy = (pl_Float) (m_cl[0].newVertices[invert].xformedy +
(m_cl[0].newVertices[nextvert].xformedy - m_cl[0].newVertices[invert].xformedy)
* scale);
m_cl[1].newVertices[outvert].xformedz = (pl_Float) (m_cl[0].newVertices[invert].xformedz +
(m_cl[0].newVertices[nextvert].xformedz - m_cl[0].newVertices[invert].xformedz)
* scale);
m_cl[1].Shades[outvert] = m_cl[0].Shades[invert] +
(m_cl[0].Shades[nextvert] - m_cl[0].Shades[invert]) * scale;
m_cl[1].MappingU[outvert] = m_cl[0].MappingU[invert] +
(m_cl[0].MappingU[nextvert] - m_cl[0].MappingU[invert]) * scale;
m_cl[1].MappingV[outvert] = m_cl[0].MappingV[invert] +
(m_cl[0].MappingV[nextvert] - m_cl[0].MappingV[invert]) * scale;
m_cl[1].eMappingU[outvert] = m_cl[0].eMappingU[invert] +
(m_cl[0].eMappingU[nextvert] - m_cl[0].eMappingU[invert]) * scale;
m_cl[1].eMappingV[outvert] = m_cl[0].eMappingV[invert] +
(m_cl[0].eMappingV[nextvert] - m_cl[0].eMappingV[invert]) * scale;
outvert++;
}
curdot = nextdot;
curin = nextin;
invert++;
}
return outvert;
}
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