diff options
Diffstat (limited to 'src/mesa/pipe/draw/draw_offset.c')
| -rw-r--r-- | src/mesa/pipe/draw/draw_offset.c | 34 |
1 files changed, 18 insertions, 16 deletions
diff --git a/src/mesa/pipe/draw/draw_offset.c b/src/mesa/pipe/draw/draw_offset.c index 0fa8cf29d3..62ab2e4643 100644 --- a/src/mesa/pipe/draw/draw_offset.c +++ b/src/mesa/pipe/draw/draw_offset.c @@ -74,32 +74,34 @@ static void do_offset_tri( struct prim_stage *stage, /* Window coords: */ - GLfloat *v0 = (GLfloat *)&(header->v[0]->data[0]); - GLfloat *v1 = (GLfloat *)&(header->v[1]->data[0]); - GLfloat *v2 = (GLfloat *)&(header->v[2]->data[0]); - + GLfloat *v0 = header->v[0]->data[0]; + GLfloat *v1 = header->v[1]->data[0]; + GLfloat *v2 = header->v[2]->data[0]; + + /* edge vectors e = v0 - v2, f = v1 - v2 */ GLfloat ex = v0[0] - v2[2]; - GLfloat fx = v1[0] - v2[2]; GLfloat ey = v0[1] - v2[2]; - GLfloat fy = v1[1] - v2[2]; GLfloat ez = v0[2] - v2[2]; + GLfloat fx = v1[0] - v2[2]; + GLfloat fy = v1[1] - v2[2]; GLfloat fz = v1[2] - v2[2]; + /* (a,b) = cross(e,f).xy */ GLfloat a = ey*fz - ez*fy; GLfloat b = ez*fx - ex*fz; - GLfloat ac = a * inv_det; - GLfloat bc = b * inv_det; - GLfloat zoffset; - - ac = FABSF(ac); - bc = FABSF(bc); + GLfloat dzdx = FABSF(a * inv_det); + GLfloat dzdy = FABSF(b * inv_det); - zoffset = offset->units + MAX2( ac, bc ) * offset->scale; + GLfloat zoffset = offset->units + MAX2(dzdx, dzdy) * offset->scale; - v0[2] += zoffset; - v1[2] += zoffset; - v2[2] += zoffset; + /* + * Note: we're applying the offset and clamping per-vertex. + * Ideally, the offset is applied per-fragment prior to fragment shading. + */ + v0[2] = CLAMP(v0[2] + zoffset, 0.0, 1.0); + v1[2] = CLAMP(v1[2] + zoffset, 0.0, 1.0); + v2[2] = CLAMP(v2[2] + zoffset, 0.0, 1.0); stage->next->tri( stage->next, header ); } |