ref: 832eb032a1ed49e8704e0178eab312a7aa47bcee
dir: /src/clip.c/
#include "zgl.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=1.0/v->pc.W;
v->zp.x= (int) ( v->pc.X * winv * c->viewport.scale.X
+ c->viewport.trans.X );
v->zp.y= (int) ( v->pc.Y * winv * c->viewport.scale.Y
+ c->viewport.trans.Y );
v->zp.z= (int) ( v->pc.Z * winv * c->viewport.scale.Z
+ c->viewport.trans.Z );
/* color */
//if (c->lighting_enabled) {
v->zp.r=(unsigned int)(v->color.v[0] * 65535) & 65535;
v->zp.g=(unsigned int)(v->color.v[1] * 65535) & 65535;
v->zp.b=(unsigned int)(v->color.v[2] * 65535) & 65535;
//} else {
//printf("\nRECEIVED COLOR %f, %f, %f, %f", v->color.v[0], v->color.v[1], v->color.v[2], v->color.v[3]);
// v->zp.r=(unsigned int)(v->color.v[0] * 65535) & 65535;
// v->zp.g=(unsigned int)(v->color.v[1] * 65535) & 65535;
// v->zp.b=(unsigned int)(v->color.v[2] * 65535) & 65535;
//printf("\nCOLORS ARE %d, %d, %d", v->zp.r,v->zp.g,v->zp.b);
// }
/* texture */
if (c->texture_2d_enabled) {
v->zp.s=(int)(v->tex_coord.X * (ZB_POINT_S_MAX - ZB_POINT_S_MIN)
+ ZB_POINT_S_MIN);
v->zp.t=(int)(v->tex_coord.Y * (ZB_POINT_T_MAX - ZB_POINT_T_MIN)
+ ZB_POINT_T_MIN);
}
}
static void gl_add_select1(GLContext *c,int z1,int z2,int z3)
{
unsigned int min,max;
min=max=z1;
if (z2<min) min=z2;
if (z3<min) min=z3;
if (z2>max) max=z2;
if (z3>max) max=z3;
gl_add_select(c,0xffffffff-min,0xffffffff-max);
}
/* point */
void gl_draw_point(GLContext *c,GLVertex *p0)
{
if (p0->clip_code == 0) {
if (c->render_mode == GL_SELECT) {
gl_add_select(c,p0->zp.z,p0->zp.z);
} else {
ZB_plot(c->zb,&p0->zp);
}
}
}
/* line */
static inline void interpolate(GLVertex *q,GLVertex *p0,GLVertex *p1,float t)
{
q->pc.X=p0->pc.X+(p1->pc.X-p0->pc.X)*t;
q->pc.Y=p0->pc.Y+(p1->pc.Y-p0->pc.Y)*t;
q->pc.Z=p0->pc.Z+(p1->pc.Z-p0->pc.Z)*t;
q->pc.W=p0->pc.W+(p1->pc.W-p0->pc.W)*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;
}
/*
* 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->render_mode == GL_SELECT) {
gl_add_select1(c,p1->zp.z,p2->zp.z,p2->zp.z);
} else {
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.X-p1->pc.X;
dy=p2->pc.Y-p1->pc.Y;
dz=p2->pc.Z-p1->pc.Z;
dw=p2->pc.W-p1->pc.W;
x1=p1->pc.X;
y1=p1->pc.Y;
z1=p1->pc.Z;
w1=p1->pc.W;
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,dX,dY,dZ,dW,den;\
dX = (b->X - a->X);\
dY = (b->Y - a->Y);\
dZ = (b->Z - a->Z);\
dW = (b->W - a->W);\
den = -(sign d ## dir) + dW;\
if (den == 0) t=0;\
else t = ( sign a->dir - a->W) / den;\
c->dir1 = a->dir1 + t * d ## dir1;\
c->dir2 = a->dir2 + t * d ## dir2;\
c->W = a->W + t * dW;\
c->dir = sign c->W;\
return t;\
}
clip_func(clip_xmin,-,X,Y,Z)
clip_func(clip_xmax,+,X,Y,Z)
clip_func(clip_ymin,-,Y,X,Z)
clip_func(clip_ymax,+,Y,X,Z)
clip_func(clip_zmin,-,Z,X,Y)
clip_func(clip_zmax,+,Z,X,Y)
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->current_shade_model == GL_SMOOTH) {
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->zp.r = p0->zp.r + (p1->zp.r - p0->zp.r)*t;
q->zp.g = p0->zp.g + (p1->zp.g - p0->zp.g)*t;
q->zp.b = p0->zp.b + (p1->zp.b - p0->zp.b)*t;
//q->color.v[3]=p0->color.v[3] + (p1->color.v[3] - p0->color.v[3])*t;
//printf("\np0 Components are %f, %f, %f", p0->color.v[0], p0->color.v[1], p0->color.v[2]);
//printf("\nZbuffer point r,g,b for p0 are: %d %d %d",p0->zp.r, p0->zp.g,p0->zp.b);
//printf("\n~\nNew Components are %f, %f, %f", q->color.v[0], q->color.v[1], q->color.v[2]);
//printf("\nZbuffer point r,g,b for new point are: %d %d %d",q->zp.r, q->zp.g,q->zp.b);
/// *
} 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->zp.r = p0->zp.r;
q->zp.g = p0->zp.g;
q->zp.b = p0->zp.b;
}
// */
if (c->texture_2d_enabled) {
q->tex_coord.X = p0->tex_coord.X + (p1->tex_coord.X-p0->tex_coord.X)*t;
q->tex_coord.Y = p0->tex_coord.Y + (p1->tex_coord.Y-p0->tex_coord.Y)*t;
}
q->clip_code=gl_clipcode(q->pc.X,q->pc.Y,q->pc.Z,q->pc.W);
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;
front = front ^ c->current_front_face;
/* back face culling */
if (c->cull_face_enabled) {
/* most used case first */
if (c->current_cull_face == GL_BACK) {
if (front == 0) return;
c->draw_triangle_front(c,p0,p1,p2);
} else if (c->current_cull_face == GL_FRONT) {
if (front != 0) return;
c->draw_triangle_back(c,p0,p1,p2);
} else {
return;
}
} 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) { //Don't draw a triangle with no points
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.X,p0->pc.Y,p0->pc.Z,p0->pc.W);
printf("%f %f %f %f\n",p1->pc.X,p1->pc.Y,p1->pc.Z,p1->pc.W);
printf("%f %f %f %f\n",p2->pc.X,p2->pc.Y,p2->pc.Z,p2->pc.W);
#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);
}
}
}
void gl_draw_triangle_select(GLContext *c,
GLVertex *p0,GLVertex *p1,GLVertex *p2)
{
gl_add_select1(c,p0->zp.z,p1->zp.z,p2->zp.z);
}
#ifdef PROFILE
int count_triangles,count_triangles_textured,count_pixels;
#endif
void gl_draw_triangle_fill(GLContext *c,
GLVertex *p0,GLVertex *p1,GLVertex *p2)
{
//puts("\n <yes, it's draw_triangle_fill>");
#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
if (c->texture_2d_enabled) {
#ifdef PROFILE
count_triangles_textured++;
#endif
ZB_setTexture(c->zb,c->current_texture->images[0].pixmap);
ZB_fillTriangleMappingPerspective(c->zb,&p0->zp,&p1->zp,&p2->zp);
} else if (c->current_shade_model == GL_SMOOTH) {
ZB_fillTriangleSmooth(c->zb,&p0->zp,&p1->zp,&p2->zp);
} else {
ZB_fillTriangleFlat(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);
}