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open_toontown_panda3d/panda/src/tinydisplay/clip.cxx

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#include "zgl.h"
#include <limits.h>
/* fill triangle profile */
/* #define PROFILE */
#define CLIP_XMIN (1<<0)
#define CLIP_XMAX (1<<1)
#define CLIP_YMIN (1<<2)
#define CLIP_YMAX (1<<3)
#define CLIP_ZMIN (1<<4)
#define CLIP_ZMAX (1<<5)
void gl_transform_to_viewport(GLContext *c,GLVertex *v)
{
float winv;
/* coordinates */
winv = 1.0f / v->pc.v[3];
v->zp.x= (int) ( v->pc.v[0] * winv * c->viewport.scale.v[0]
+ c->viewport.trans.v[0] );
v->zp.y= (int) ( v->pc.v[1] * winv * c->viewport.scale.v[1]
+ c->viewport.trans.v[1] );
v->zp.z= (int) ( v->pc.v[2] * winv * c->viewport.scale.v[2]
+ c->viewport.trans.v[2] );
// Add the z-bias, if any. Be careful not to overflow the int.
int z = v->zp.z + (c->zbias << (ZB_POINT_Z_FRAC_BITS + 4));
if (z < v->zp.z && c->zbias > 0) {
v->zp.z = INT_MAX;
} else if (z > v->zp.z && c->zbias < 0) {
v->zp.z = -INT_MAX;
} else {
v->zp.z = z;
}
/* color */
v->zp.r=(int)(v->color.v[0] * (ZB_POINT_RED_MAX - ZB_POINT_RED_MIN)
+ ZB_POINT_RED_MIN);
v->zp.g=(int)(v->color.v[1] * (ZB_POINT_GREEN_MAX - ZB_POINT_GREEN_MIN)
+ ZB_POINT_GREEN_MIN);
v->zp.b=(int)(v->color.v[2] * (ZB_POINT_BLUE_MAX - ZB_POINT_BLUE_MIN)
+ ZB_POINT_BLUE_MIN);
v->zp.a=(int)(v->color.v[3] * (ZB_POINT_ALPHA_MAX - ZB_POINT_ALPHA_MIN)
+ ZB_POINT_ALPHA_MIN);
/* texture */
if (c->num_textures_enabled >= 1) {
static const int si = 0;
v->zp.s = (int)(v->tex_coord[si].v[0] * c->current_textures[si]->s_max);
v->zp.t = (int)(v->tex_coord[si].v[1] * c->current_textures[si]->t_max);
}
if (c->num_textures_enabled >= 2) {
static const int si = 1;
v->zp.sa = (int)(v->tex_coord[si].v[0] * c->current_textures[si]->s_max);
v->zp.ta = (int)(v->tex_coord[si].v[1] * c->current_textures[si]->t_max);
}
if (c->num_textures_enabled >= 3) {
static const int si = 2;
v->zp.sb = (int)(v->tex_coord[si].v[0] * c->current_textures[si]->s_max);
v->zp.tb = (int)(v->tex_coord[si].v[1] * c->current_textures[si]->t_max);
}
}
/* point */
void gl_draw_point(GLContext *c,GLVertex *p0)
{
if (p0->clip_code == 0) {
ZB_plot(c->zb,&p0->zp);
}
}
/* line */
static inline void interpolate(GLVertex *q,GLVertex *p0,GLVertex *p1,float t)
{
q->pc.v[0]=p0->pc.v[0]+(p1->pc.v[0]-p0->pc.v[0])*t;
q->pc.v[1]=p0->pc.v[1]+(p1->pc.v[1]-p0->pc.v[1])*t;
q->pc.v[2]=p0->pc.v[2]+(p1->pc.v[2]-p0->pc.v[2])*t;
q->pc.v[3]=p0->pc.v[3]+(p1->pc.v[3]-p0->pc.v[3])*t;
q->color.v[0]=p0->color.v[0] + (p1->color.v[0]-p0->color.v[0])*t;
q->color.v[1]=p0->color.v[1] + (p1->color.v[1]-p0->color.v[1])*t;
q->color.v[2]=p0->color.v[2] + (p1->color.v[2]-p0->color.v[2])*t;
q->color.v[3]=p0->color.v[3] + (p1->color.v[3]-p0->color.v[3])*t;
}
/*
* Line Clipping
*/
/* Line Clipping algorithm from 'Computer Graphics', Principles and
Practice */
static inline int ClipLine1(float denom,float num,float *tmin,float *tmax)
{
float t;
if (denom>0) {
t=num/denom;
if (t>*tmax) return 0;
if (t>*tmin) *tmin=t;
} else if (denom<0) {
t=num/denom;
if (t<*tmin) return 0;
if (t<*tmax) *tmax=t;
} else if (num>0) return 0;
return 1;
}
void gl_draw_line(GLContext *c,GLVertex *p1,GLVertex *p2)
{
float dx,dy,dz,dw,x1,y1,z1,w1;
float tmin,tmax;
GLVertex q1,q2;
int cc1,cc2;
cc1=p1->clip_code;
cc2=p2->clip_code;
if ( (cc1 | cc2) == 0) {
if (c->depth_test)
ZB_line_z(c->zb,&p1->zp,&p2->zp);
else
ZB_line(c->zb,&p1->zp,&p2->zp);
} else if ( (cc1&cc2) != 0 ) {
return;
} else {
dx=p2->pc.v[0]-p1->pc.v[0];
dy=p2->pc.v[1]-p1->pc.v[1];
dz=p2->pc.v[2]-p1->pc.v[2];
dw=p2->pc.v[3]-p1->pc.v[3];
x1=p1->pc.v[0];
y1=p1->pc.v[1];
z1=p1->pc.v[2];
w1=p1->pc.v[3];
tmin=0;
tmax=1;
if (ClipLine1(dx+dw,-x1-w1,&tmin,&tmax) &&
ClipLine1(-dx+dw,x1-w1,&tmin,&tmax) &&
ClipLine1(dy+dw,-y1-w1,&tmin,&tmax) &&
ClipLine1(-dy+dw,y1-w1,&tmin,&tmax) &&
ClipLine1(dz+dw,-z1-w1,&tmin,&tmax) &&
ClipLine1(-dz+dw,z1-w1,&tmin,&tmax)) {
interpolate(&q1,p1,p2,tmin);
interpolate(&q2,p1,p2,tmax);
gl_transform_to_viewport(c,&q1);
gl_transform_to_viewport(c,&q2);
if (c->depth_test)
ZB_line_z(c->zb,&q1.zp,&q2.zp);
else
ZB_line(c->zb,&q1.zp,&q2.zp);
}
}
}
/* triangle */
/*
* Clipping
*/
/* We clip the segment [a,b] against the 6 planes of the normal volume.
* We compute the point 'c' of intersection and the value of the parameter 't'
* of the intersection if x=a+t(b-a).
*/
#define clip_func(name, sign, dir, dir1, dir2) \
static float name(V4 *c, V4 *a, V4 *b) \
{\
float t,den;\
float d[4];\
d[0] = (b->v[0] - a->v[0]);\
d[1] = (b->v[1] - a->v[1]);\
d[2] = (b->v[2] - a->v[2]);\
d[3] = (b->v[3] - a->v[3]);\
den = -(sign d[dir]) + d[3];\
if (den == 0) t=0;\
else t = ( sign a->v[dir] - a->v[3]) / den;\
c->v[dir1] = a->v[dir1] + t * d[dir1];\
c->v[dir2] = a->v[dir2] + t * d[dir2];\
c->v[3] = a->v[3] + t * d[3];\
c->v[dir] = sign c->v[3];\
return t;\
}
clip_func(clip_xmin, -, 0, 1, 2)
clip_func(clip_xmax, +, 0, 1, 2)
clip_func(clip_ymin, -, 1, 0, 2)
clip_func(clip_ymax, +, 1, 0, 2)
clip_func(clip_zmin, -, 2, 0, 1)
clip_func(clip_zmax, +, 2, 0, 1)
float (*clip_proc[6])(V4 *,V4 *,V4 *)= {
clip_xmin,clip_xmax,
clip_ymin,clip_ymax,
clip_zmin,clip_zmax
};
static inline void updateTmp(GLContext *c,
GLVertex *q,GLVertex *p0,GLVertex *p1,float t)
{
if (c->smooth_shade_model) {
q->color.v[0]=p0->color.v[0] + (p1->color.v[0]-p0->color.v[0])*t;
q->color.v[1]=p0->color.v[1] + (p1->color.v[1]-p0->color.v[1])*t;
q->color.v[2]=p0->color.v[2] + (p1->color.v[2]-p0->color.v[2])*t;
q->color.v[3]=p0->color.v[3] + (p1->color.v[3]-p0->color.v[3])*t;
} else {
q->color.v[0]=p0->color.v[0];
q->color.v[1]=p0->color.v[1];
q->color.v[2]=p0->color.v[2];
q->color.v[3]=p0->color.v[3];
}
for (int si = 0; si < c->num_textures_enabled; ++si) {
q->tex_coord[si].v[0]=p0->tex_coord[si].v[0] + (p1->tex_coord[si].v[0]-p0->tex_coord[si].v[0])*t;
q->tex_coord[si].v[1]=p0->tex_coord[si].v[1] + (p1->tex_coord[si].v[1]-p0->tex_coord[si].v[1])*t;
}
q->clip_code=gl_clipcode(q->pc.v[0],q->pc.v[1],q->pc.v[2],q->pc.v[3]);
if (q->clip_code==0) {
gl_transform_to_viewport(c,q);
}
}
static void gl_draw_triangle_clip(GLContext *c,
GLVertex *p0,GLVertex *p1,GLVertex *p2,int clip_bit);
void gl_draw_triangle(GLContext *c,
GLVertex *p0,GLVertex *p1,GLVertex *p2)
{
int co,c_and,cc[3],front;
float norm;
cc[0]=p0->clip_code;
cc[1]=p1->clip_code;
cc[2]=p2->clip_code;
co=cc[0] | cc[1] | cc[2];
/* we handle the non clipped case here to go faster */
if (co==0) {
norm=(float)(p1->zp.x-p0->zp.x)*(float)(p2->zp.y-p0->zp.y)-
(float)(p2->zp.x-p0->zp.x)*(float)(p1->zp.y-p0->zp.y);
if (norm == 0) return;
front = norm < 0.0;
/* back face culling */
if (c->cull_face_enabled) {
/* most used case first */
if (c->cull_clockwise) {
if (front == 0) return;
c->draw_triangle_front(c,p0,p1,p2);
} else {
if (front != 0) return;
c->draw_triangle_back(c,p0,p1,p2);
}
} else {
/* no culling */
if (front) {
c->draw_triangle_front(c,p0,p1,p2);
} else {
c->draw_triangle_back(c,p0,p1,p2);
}
}
} else {
c_and=cc[0] & cc[1] & cc[2];
if (c_and==0) {
gl_draw_triangle_clip(c,p0,p1,p2,0);
}
}
}
static void gl_draw_triangle_clip(GLContext *c,
GLVertex *p0,GLVertex *p1,GLVertex *p2,int clip_bit)
{
int co,c_and,co1,cc[3],edge_flag_tmp,clip_mask;
GLVertex tmp1,tmp2,*q[3];
float tt;
cc[0]=p0->clip_code;
cc[1]=p1->clip_code;
cc[2]=p2->clip_code;
co=cc[0] | cc[1] | cc[2];
if (co == 0) {
gl_draw_triangle(c,p0,p1,p2);
} else {
c_and=cc[0] & cc[1] & cc[2];
/* the triangle is completely outside */
if (c_and!=0) return;
/* find the next direction to clip */
while (clip_bit < 6 && (co & (1 << clip_bit)) == 0) {
clip_bit++;
}
/* this test can be true only in case of rounding errors */
if (clip_bit == 6) {
#if 0
printf("Error:\n");
printf("%f %f %f %f\n",p0->pc.v[0],p0->pc.v[1],p0->pc.v[2],p0->pc.v[3]);
printf("%f %f %f %f\n",p1->pc.v[0],p1->pc.v[1],p1->pc.v[2],p1->pc.v[3]);
printf("%f %f %f %f\n",p2->pc.v[0],p2->pc.v[1],p2->pc.v[2],p2->pc.v[3]);
#endif
return;
}
clip_mask = 1 << clip_bit;
co1=(cc[0] ^ cc[1] ^ cc[2]) & clip_mask;
if (co1) {
/* one point outside */
if (cc[0] & clip_mask) { q[0]=p0; q[1]=p1; q[2]=p2; }
else if (cc[1] & clip_mask) { q[0]=p1; q[1]=p2; q[2]=p0; }
else { q[0]=p2; q[1]=p0; q[2]=p1; }
tt=clip_proc[clip_bit](&tmp1.pc,&q[0]->pc,&q[1]->pc);
updateTmp(c,&tmp1,q[0],q[1],tt);
tt=clip_proc[clip_bit](&tmp2.pc,&q[0]->pc,&q[2]->pc);
updateTmp(c,&tmp2,q[0],q[2],tt);
tmp1.edge_flag=q[0]->edge_flag;
edge_flag_tmp=q[2]->edge_flag;
q[2]->edge_flag=0;
gl_draw_triangle_clip(c,&tmp1,q[1],q[2],clip_bit+1);
tmp2.edge_flag=1;
tmp1.edge_flag=0;
q[2]->edge_flag=edge_flag_tmp;
gl_draw_triangle_clip(c,&tmp2,&tmp1,q[2],clip_bit+1);
} else {
/* two points outside */
if ((cc[0] & clip_mask)==0) { q[0]=p0; q[1]=p1; q[2]=p2; }
else if ((cc[1] & clip_mask)==0) { q[0]=p1; q[1]=p2; q[2]=p0; }
else { q[0]=p2; q[1]=p0; q[2]=p1; }
tt=clip_proc[clip_bit](&tmp1.pc,&q[0]->pc,&q[1]->pc);
updateTmp(c,&tmp1,q[0],q[1],tt);
tt=clip_proc[clip_bit](&tmp2.pc,&q[0]->pc,&q[2]->pc);
updateTmp(c,&tmp2,q[0],q[2],tt);
tmp1.edge_flag=1;
tmp2.edge_flag=q[2]->edge_flag;
gl_draw_triangle_clip(c,q[0],&tmp1,&tmp2,clip_bit+1);
}
}
}
#ifdef PROFILE
int count_triangles,count_triangles_textured,count_pixels;
#endif
void gl_draw_triangle_fill(GLContext *c,
GLVertex *p0,GLVertex *p1,GLVertex *p2)
{
#ifdef PROFILE
{
int norm;
assert(p0->zp.x >= 0 && p0->zp.x < c->zb->xsize);
assert(p0->zp.y >= 0 && p0->zp.y < c->zb->ysize);
assert(p1->zp.x >= 0 && p1->zp.x < c->zb->xsize);
assert(p1->zp.y >= 0 && p1->zp.y < c->zb->ysize);
assert(p2->zp.x >= 0 && p2->zp.x < c->zb->xsize);
assert(p2->zp.y >= 0 && p2->zp.y < c->zb->ysize);
norm=(p1->zp.x-p0->zp.x)*(p2->zp.y-p0->zp.y)-
(p2->zp.x-p0->zp.x)*(p1->zp.y-p0->zp.y);
count_pixels+=abs(norm)/2;
count_triangles++;
}
#endif
#ifdef PROFILE
if (c->num_textures_enabled != 0) {
count_triangles_textured++;
}
#endif
(*c->zb_fill_tri)(c->zb,&p0->zp,&p1->zp,&p2->zp);
}
/* Render a clipped triangle in line mode */
void gl_draw_triangle_line(GLContext *c,
GLVertex *p0,GLVertex *p1,GLVertex *p2)
{
if (c->depth_test) {
if (p0->edge_flag) ZB_line_z(c->zb,&p0->zp,&p1->zp);
if (p1->edge_flag) ZB_line_z(c->zb,&p1->zp,&p2->zp);
if (p2->edge_flag) ZB_line_z(c->zb,&p2->zp,&p0->zp);
} else {
if (p0->edge_flag) ZB_line(c->zb,&p0->zp,&p1->zp);
if (p1->edge_flag) ZB_line(c->zb,&p1->zp,&p2->zp);
if (p2->edge_flag) ZB_line(c->zb,&p2->zp,&p0->zp);
}
}
/* Render a clipped triangle in point mode */
void gl_draw_triangle_point(GLContext *c,
GLVertex *p0,GLVertex *p1,GLVertex *p2)
{
if (p0->edge_flag) ZB_plot(c->zb,&p0->zp);
if (p1->edge_flag) ZB_plot(c->zb,&p1->zp);
if (p2->edge_flag) ZB_plot(c->zb,&p2->zp);
}
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