diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/mesa/main/ffvertex_prog.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/src/mesa/main/ffvertex_prog.c b/src/mesa/main/ffvertex_prog.c index 859f72b4586..03f42704a7d 100644 --- a/src/mesa/main/ffvertex_prog.c +++ b/src/mesa/main/ffvertex_prog.c @@ -1108,6 +1108,9 @@ static void build_lighting( struct tnl_program *p ) if (twoside) { if (!p->state->material_shininess_is_zero) { + /* Note that we negate the back-face specular exponent here. + * The negation will be un-done later in the back-face code below. + */ struct ureg shininess = get_material(p, 1, STATE_SHININESS); emit_op1(p, OPCODE_MOV, dots, WRITEMASK_Z, negate(swizzle1(shininess,X))); @@ -1316,6 +1319,11 @@ static void build_lighting( struct tnl_program *p ) mask1 = 0; } + /* For the back face we need to negate the X and Y component + * dot products. dots.Z has the negated back-face specular + * exponent. We swizzle that into the W position. This + * negation makes the back-face specular term positive again. + */ dots = negate(swizzle(dots,X,Y,W,Z)); if (!is_undef(att)) { @@ -1334,8 +1342,10 @@ static void build_lighting( struct tnl_program *p ) emit_op3(p, OPCODE_MAD, res0, mask0, swizzle1(lit,Y), diffuse, _bfc0); emit_op3(p, OPCODE_MAD, res1, mask1, swizzle1(lit,Z), specular, _bfc1); - /* restore negate flag for next lighting */ - dots = negate(dots); + /* restore dots to its original state for subsequent lights + * by negating and swizzling again. + */ + dots = negate(swizzle(dots,X,Y,W,Z)); release_temp(p, ambient); release_temp(p, diffuse); |