ref: 4c66d61f63d2ca97101d7aad96c6fb412fbc6c4b
dir: /r_aclip.c/
// r_aclip.c: clip routines for drawing Alias models directly to the screen
#include <u.h>
#include <libc.h>
#include <stdio.h>
#include "dat.h"
#include "fns.h"
static finalvert_t fv[2][8];
void R_AliasProjectAndClipTestFinalVert (finalvert_t *fv);
void R_Alias_clip_top (finalvert_t *pfv0, finalvert_t *pfv1,
finalvert_t *out);
void R_Alias_clip_bottom (finalvert_t *pfv0, finalvert_t *pfv1,
finalvert_t *out);
void R_Alias_clip_left (finalvert_t *pfv0, finalvert_t *pfv1,
finalvert_t *out);
void R_Alias_clip_right (finalvert_t *pfv0, finalvert_t *pfv1,
finalvert_t *out);
/*
================
R_Alias_clip_z
pfv0 is the unclipped vertex, pfv1 is the z-clipped vertex
================
*/
void R_Alias_clip_z (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
float scale;
scale = (ALIAS_Z_CLIP_PLANE - pfv0->xyz[2]) /
(pfv1->xyz[2] - pfv0->xyz[2]);
out->xyz[0] = pfv0->xyz[0] + (pfv1->xyz[0] - pfv0->xyz[0]) * scale;
out->xyz[1] = pfv0->xyz[1] + (pfv1->xyz[1] - pfv0->xyz[1]) * scale;
out->xyz[2] = ALIAS_Z_CLIP_PLANE;
out->s = pfv0->s + (pfv1->s - pfv0->s) * scale;
out->t = pfv0->t + (pfv1->t - pfv0->t) * scale;
out->l = pfv0->l + (pfv1->l - pfv0->l) * scale;
R_AliasProjectAndClipTestFinalVert (out);
}
void R_Alias_clip_left (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
float scale;
if (pfv0->v >= pfv1->v )
{
scale = (float)(r_refdef.aliasvrect.x - pfv0->u) /
(pfv1->u - pfv0->u);
out->u = pfv0->u + ( pfv1->u - pfv0->u ) * scale + 0.5;
out->v = pfv0->v + ( pfv1->v - pfv0->v ) * scale + 0.5;
out->s = pfv0->s + ( pfv1->s - pfv0->s ) * scale + 0.5;
out->t = pfv0->t + ( pfv1->t - pfv0->t ) * scale + 0.5;
out->l = pfv0->l + ( pfv1->l - pfv0->l ) * scale + 0.5;
out->zi = pfv0->zi + ( pfv1->zi - pfv0->zi) * scale + 0.5;
}
else
{
scale = (float)(r_refdef.aliasvrect.x - pfv1->u) /
(pfv0->u - pfv1->u);
out->u = pfv1->u + ( pfv0->u - pfv1->u ) * scale + 0.5;
out->v = pfv1->v + ( pfv0->v - pfv1->v ) * scale + 0.5;
out->s = pfv1->s + ( pfv0->s - pfv1->s ) * scale + 0.5;
out->t = pfv1->t + ( pfv0->t - pfv1->t ) * scale + 0.5;
out->l = pfv1->l + ( pfv0->l - pfv1->l ) * scale + 0.5;
out->zi = pfv1->zi + ( pfv0->zi - pfv1->zi) * scale + 0.5;
}
}
void R_Alias_clip_right (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
float scale;
if ( pfv0->v >= pfv1->v )
{
scale = (float)(r_refdef.aliasvrectright - pfv0->u ) /
(pfv1->u - pfv0->u );
out->u = pfv0->u + ( pfv1->u - pfv0->u ) * scale + 0.5;
out->v = pfv0->v + ( pfv1->v - pfv0->v ) * scale + 0.5;
out->s = pfv0->s + ( pfv1->s - pfv0->s ) * scale + 0.5;
out->t = pfv0->t + ( pfv1->t - pfv0->t ) * scale + 0.5;
out->l = pfv0->l + ( pfv1->l - pfv0->l ) * scale + 0.5;
out->zi = pfv0->zi + ( pfv1->zi - pfv0->zi) * scale + 0.5;
}
else
{
scale = (float)(r_refdef.aliasvrectright - pfv1->u ) /
(pfv0->u - pfv1->u );
out->u = pfv1->u + ( pfv0->u - pfv1->u ) * scale + 0.5;
out->v = pfv1->v + ( pfv0->v - pfv1->v ) * scale + 0.5;
out->s = pfv1->s + ( pfv0->s - pfv1->s ) * scale + 0.5;
out->t = pfv1->t + ( pfv0->t - pfv1->t ) * scale + 0.5;
out->l = pfv1->l + ( pfv0->l - pfv1->l ) * scale + 0.5;
out->zi = pfv1->zi + ( pfv0->zi - pfv1->zi) * scale + 0.5;
}
}
void R_Alias_clip_top (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
float scale;
if (pfv0->v >= pfv1->v)
{
scale = (float)(r_refdef.aliasvrect.y - pfv0->v) /
(pfv1->v - pfv0->v);
out->u = pfv0->u + ( pfv1->u - pfv0->u ) * scale + 0.5;
out->v = pfv0->v + ( pfv1->v - pfv0->v ) * scale + 0.5;
out->s = pfv0->s + ( pfv1->s - pfv0->s ) * scale + 0.5;
out->t = pfv0->t + ( pfv1->t - pfv0->t ) * scale + 0.5;
out->l = pfv0->l + ( pfv1->l - pfv0->l ) * scale + 0.5;
out->zi = pfv0->zi + ( pfv1->zi - pfv0->zi) * scale + 0.5;
}
else
{
scale = (float)(r_refdef.aliasvrect.y - pfv1->v) /
(pfv0->v - pfv1->v);
out->u = pfv1->u + ( pfv0->u - pfv1->u ) * scale + 0.5;
out->v = pfv1->v + ( pfv0->v - pfv1->v ) * scale + 0.5;
out->s = pfv1->s + ( pfv0->s - pfv1->s ) * scale + 0.5;
out->t = pfv1->t + ( pfv0->t - pfv1->t ) * scale + 0.5;
out->l = pfv1->l + ( pfv0->l - pfv1->l ) * scale + 0.5;
out->zi = pfv1->zi + ( pfv0->zi - pfv1->zi) * scale + 0.5;
}
}
void R_Alias_clip_bottom (finalvert_t *pfv0, finalvert_t *pfv1,
finalvert_t *out)
{
float scale;
if (pfv0->v >= pfv1->v)
{
scale = (float)(r_refdef.aliasvrectbottom - pfv0->v) /
(pfv1->v - pfv0->v);
out->u = pfv0->u + ( pfv1->u - pfv0->u ) * scale + 0.5;
out->v = pfv0->v + ( pfv1->v - pfv0->v ) * scale + 0.5;
out->s = pfv0->s + ( pfv1->s - pfv0->s ) * scale + 0.5;
out->t = pfv0->t + ( pfv1->t - pfv0->t ) * scale + 0.5;
out->l = pfv0->l + ( pfv1->l - pfv0->l ) * scale + 0.5;
out->zi = pfv0->zi + ( pfv1->zi - pfv0->zi) * scale + 0.5;
}
else
{
scale = (float)(r_refdef.aliasvrectbottom - pfv1->v) /
(pfv0->v - pfv1->v);
out->u = pfv1->u + ( pfv0->u - pfv1->u ) * scale + 0.5;
out->v = pfv1->v + ( pfv0->v - pfv1->v ) * scale + 0.5;
out->s = pfv1->s + ( pfv0->s - pfv1->s ) * scale + 0.5;
out->t = pfv1->t + ( pfv0->t - pfv1->t ) * scale + 0.5;
out->l = pfv1->l + ( pfv0->l - pfv1->l ) * scale + 0.5;
out->zi = pfv1->zi + ( pfv0->zi - pfv1->zi) * scale + 0.5;
}
}
int R_AliasClip (finalvert_t *in, finalvert_t *out, int flag, int count,
void(*clip)(finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out) )
{
int i,j,k;
int flags, oldflags;
j = count-1;
k = 0;
for (i=0 ; i<count ; j = i, i++)
{
oldflags = in[j].flags & flag;
flags = in[i].flags & flag;
if (flags && oldflags)
continue;
if (oldflags ^ flags)
{
clip (&in[j], &in[i], &out[k]);
out[k].flags = 0;
if (out[k].u < r_refdef.aliasvrect.x)
out[k].flags |= ALIAS_LEFT_CLIP;
if (out[k].v < r_refdef.aliasvrect.y)
out[k].flags |= ALIAS_TOP_CLIP;
if (out[k].u > r_refdef.aliasvrectright)
out[k].flags |= ALIAS_RIGHT_CLIP;
if (out[k].v > r_refdef.aliasvrectbottom)
out[k].flags |= ALIAS_BOTTOM_CLIP;
k++;
}
if (!flags)
{
out[k] = in[i];
k++;
}
}
return k;
}
/*
================
R_AliasClipTriangle
================
*/
void R_AliasClipTriangle (finalvert_t *index0, finalvert_t *index1, finalvert_t *index2)
{
int i, k, pingpong;
unsigned clipflags;
// copy vertexes and fix seam texture coordinates
fv[0][0] = *index0;
fv[0][1] = *index1;
fv[0][2] = *index2;
// clip
clipflags = fv[0][0].flags | fv[0][1].flags | fv[0][2].flags;
if (clipflags & ALIAS_Z_CLIP)
{
k = R_AliasClip (fv[0], fv[1], ALIAS_Z_CLIP, 3, R_Alias_clip_z);
if (k == 0)
return;
pingpong = 1;
clipflags = fv[1][0].flags | fv[1][1].flags | fv[1][2].flags;
}
else
{
pingpong = 0;
k = 3;
}
if (clipflags & ALIAS_LEFT_CLIP)
{
k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
ALIAS_LEFT_CLIP, k, R_Alias_clip_left);
if (k == 0)
return;
pingpong ^= 1;
}
if (clipflags & ALIAS_RIGHT_CLIP)
{
k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
ALIAS_RIGHT_CLIP, k, R_Alias_clip_right);
if (k == 0)
return;
pingpong ^= 1;
}
if (clipflags & ALIAS_BOTTOM_CLIP)
{
k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
ALIAS_BOTTOM_CLIP, k, R_Alias_clip_bottom);
if (k == 0)
return;
pingpong ^= 1;
}
if (clipflags & ALIAS_TOP_CLIP)
{
k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
ALIAS_TOP_CLIP, k, R_Alias_clip_top);
if (k == 0)
return;
pingpong ^= 1;
}
for (i=0 ; i<k ; i++)
{
if (fv[pingpong][i].u < r_refdef.aliasvrect.x)
fv[pingpong][i].u = r_refdef.aliasvrect.x;
else if (fv[pingpong][i].u > r_refdef.aliasvrectright)
fv[pingpong][i].u = r_refdef.aliasvrectright;
if (fv[pingpong][i].v < r_refdef.aliasvrect.y)
fv[pingpong][i].v = r_refdef.aliasvrect.y;
else if (fv[pingpong][i].v > r_refdef.aliasvrectbottom)
fv[pingpong][i].v = r_refdef.aliasvrectbottom;
fv[pingpong][i].flags = 0;
}
// draw triangles
for (i=1 ; i<k-1 ; i++)
{
aliastriangleparms.a = &fv[pingpong][0];
aliastriangleparms.b = &fv[pingpong][i];
aliastriangleparms.c = &fv[pingpong][i+1];
R_DrawTriangle();
}
}