diff options
| -rw-r--r-- | render.c | 159 |
1 files changed, 146 insertions, 13 deletions
@@ -89,20 +89,81 @@ triangulate(OBJElem **newe, OBJElem *e) } static int -isclipping(Point3 p) +isvisible(Point3 p) { if(p.x < -p.w || p.x > p.w || p.y < -p.w || p.y > p.w || p.z < -p.w || p.z > p.w) - return 1; - return 0; + return 0; + return 1; } +static void +mulsdm(double r[6], double m[6][4], Point3 p) +{ + int i; + + for(i = 0; i < 6; i++) + r[i] += m[i][0]*p.x + m[i][1]*p.y + m[i][2]*p.z + m[i][3]*p.w; +} + +typedef struct +{ + Vertex *v; + ulong n; + ulong cap; +} Polygon; + +typedef struct +{ + ulong *idx; + ulong nidx; + ulong cap; +} Cliplist; + static int -cliptriangle(Triangle *) +addvert(Polygon *p, Vertex v) { - /* TODO implement homogeneous clipping procedure */ + if(++p->n > p->cap) + p->v = erealloc(p->v, (p->cap = p->n)*sizeof(*p->v)); + p->v[p->n-1] = v; + return p->n; +} + +static void +delvert(Polygon *p, ulong idx) +{ + if(--p->n > 1 && idx < p->cap-1) + memmove(&p->v[idx], &p->v[idx+1], p->n); +} + +static int +addidx(Cliplist *l, ulong idx) +{ + if(++l->nidx > l->cap) + l->idx = erealloc(l->idx, (l->cap = l->nidx)*sizeof(*l->idx)); + l->idx[l->nidx-1] = idx; + return l->nidx; +} + +static int +idxcmp(ulong *a, ulong *b) +{ + return *a - *b; +} + +static void +reapverts(Polygon *p, Cliplist *l) +{ + qsort(l->idx, l->nidx, sizeof(l->idx[0]), (int(*)(void*,void*))idxcmp); + while(l->nidx--) + delvert(p, l->idx[l->nidx]); +} +static int +cliptriangle(Triangle *t) +{ + /* TODO implement homogeneous clipping procedure */ /* * requirements: * @@ -111,6 +172,49 @@ cliptriangle(Triangle *) * - uv coordinates must be adjusted in proportion to the new * points. */ + enum { L, R, B, T, F, N }; + /* signed distance from each clipping plane */ + static double sdm[6][4] = { + 1, 0, 0, 1, + -1, 0, 0, 1, + 0, 1, 0, 1, + 0, -1, 0, 1, + 0, 0, 1, 1, + 0, 0, -1, 1, + }, sd0[6], sd1[6]; + Polygon V; /* new polygon verts */ + Cliplist D; /* verts to delete */ + Vertex v; /* new vertex (line-plane intersection) */ + int i, j; + + if(!isvisible(t[0][0].p) && !isvisible(t[0][1].p) && !isvisible(t[0][2].p)) + return 0; + + memset(&V, 0, sizeof V); + memset(&D, 0, sizeof D); + /* initialize with the original triangle */ +// for(i = 0; i < 3; i++) +// addvert(&V, t[0][i]); +// +// for(i = 0; i < V.n-1; i++){ +// memset(sd0, 0, sizeof sd0); +// memset(sd1, 0, sizeof sd1); +// mulsdm(sd0, sdm, V.v[i].p); +// mulsdm(sd1, sdm, V.v[i+1].p); +// +// for(j = 0; j < 6; j++){ +// if(sd0[i] < 0 && sd1[i] < 0){ +// addidx(&D, i); +// addidx(&D, i+1); +// }else if(sd0[i] < 0){ +// addidx(&D, i); +// }else if(sd1[i] < 0){ +// addidx(&D, i+1); +// } +// reapverts(&V, &D); +// } +// } + return 1; } @@ -151,13 +255,20 @@ world2clip(Camera *c, Point3 p) /* * performs the perspective division, placing - * p.[xyz] ∈ [-1,1] and p.w = 1 + * p.[xyz] ∈ [-1,1] and p.w = 1/z * (aka Normalized Device Coordinates). + * + * p.w is kept as z⁻¹ so we can later do + * perspective-correct attribute interpolation. */ static Point3 clip2ndc(Point3 p) { - return divpt3(p, p.w); + p.w = 1.0/p.w; + p.x *= p.w; + p.y *= p.w; + p.z *= p.w; + return p; } /* @@ -174,8 +285,13 @@ ndc2viewport(Framebuf *fb, Point3 p) 0, 0, 1.0/2.0, 1.0/2.0, 0, 0, 0, 1, }; + double w; - return xform3(p, view); + w = p.w; + p.w = 1; + p = xform3(p, view); + p.w = w; + return p; } void @@ -232,6 +348,14 @@ rasterize(SUparams *params, Triangle t, Memimage *frag) fsp.frag = frag; fsp.cbuf = cbuf; + /* perspective-divide the attributes */ +// t[0].c = mulpt3(t[0].c, t[0].p.w); +// t[1].c = mulpt3(t[1].c, t[1].p.w); +// t[2].c = mulpt3(t[2].c, t[2].p.w); + t[0].uv = mulpt2(t[0].uv, t[0].p.w); + t[1].uv = mulpt2(t[1].uv, t[1].p.w); + t[2].uv = mulpt2(t[2].uv, t[2].p.w); + for(p.y = bbox.min.y; p.y < bbox.max.y; p.y++) for(p.x = bbox.min.x; p.x < bbox.max.x; p.x++){ bc = barycoords(t₂, Pt2(p.x,p.y,1)); @@ -248,11 +372,20 @@ rasterize(SUparams *params, Triangle t, Memimage *frag) params->fb->zbuf[p.x + p.y*Dx(params->fb->r)] = depth; unlock(¶ms->fb->zbuflk); + /* lerp z⁻¹ and get actual z */ + z = t[0].p.w*bc.x + t[1].p.w*bc.y + t[2].p.w*bc.z; + z = 1.0/(z < 1e-6? 1e-6: z); + + /* lerp attribute and dissolve perspective */ +// t[0].c = mulpt3(t[0].c, bc.x*z); +// t[1].c = mulpt3(t[1].c, bc.y*z); +// t[2].c = mulpt3(t[2].c, bc.z*z); + cbuf[0] = 0xFF; if((t[0].uv.w + t[1].uv.w + t[2].uv.w) != 0){ - tt₂.p0 = mulpt2(t[0].uv, bc.x); - tt₂.p1 = mulpt2(t[1].uv, bc.y); - tt₂.p2 = mulpt2(t[2].uv, bc.z); + tt₂.p0 = mulpt2(t[0].uv, bc.x*z); + tt₂.p1 = mulpt2(t[1].uv, bc.y*z); + tt₂.p2 = mulpt2(t[2].uv, bc.z*z); tp.x = (tt₂.p0.x + tt₂.p1.x + tt₂.p2.x)*Dx(params->modeltex->r); tp.y = (1 - (tt₂.p0.y + tt₂.p1.y + tt₂.p2.y))*Dy(params->modeltex->r); @@ -284,7 +417,7 @@ shaderunit(void *arg) OBJIndexArray *idxtab; OBJElem **ep; Point3 n; /* surface normal */ - Triangle t[2*3]; /* triangles to raster */ + Triangle t[7-2]; /* triangles to raster */ int nt; params = arg; @@ -338,7 +471,7 @@ shaderunit(void *arg) vsp.idx = 2; t[0][2].p = params->vshader(&vsp); - if(isclipping(t[0][0].p) || isclipping(t[0][1].p) || isclipping(t[0][2].p)) + if(!isvisible(t[0][0].p) || !isvisible(t[0][1].p) || !isvisible(t[0][2].p)) nt = cliptriangle(t); while(nt--){ |