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fix span->facing computation and gl_FrontFacing initialization

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This commit is contained in:
Brian 2007-12-04 14:06:01 -07:00
parent c135426267
commit 385bddbde0
2 changed files with 5 additions and 7 deletions
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2
src/mesa/swrast/s_fragprog.c
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@ -118,7 +118,7 @@ init_machine(GLcontext *ctx, struct gl_program_machine *machine,
if (ctx->Shader.CurrentProgram) {
/* Store front/back facing value in register FOGC.Y */
machine->Attribs[FRAG_ATTRIB_FOGC][col][1] = (GLfloat) span->facing;
machine->Attribs[FRAG_ATTRIB_FOGC][col][1] = 1.0 - span->facing;
}
machine->CurElement = col;

10
src/mesa/swrast/s_tritemp.h
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@ -172,7 +172,7 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
EdgeT eMaj, eTop, eBot;
GLfloat oneOverArea;
const SWvertex *vMin, *vMid, *vMax; /* Y(vMin)<=Y(vMid)<=Y(vMax) */
GLfloat bf = SWRAST_CONTEXT(ctx)->_BackfaceCullSign;
GLfloat bf = SWRAST_CONTEXT(ctx)->_BackfaceSign;
#if !TRIANGLE_WALK_DOUBLE
const GLint snapMask = ~((FIXED_ONE / (1 << SUB_PIXEL_BITS)) - 1); /* for x/y coord snapping */
#endif
@ -292,18 +292,16 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
#else
const GLfloat area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy;
#endif
/* Do backface culling */
if (area * bf < 0.0)
if (IS_INF_OR_NAN(area) || area == 0.0F)
return;
if (IS_INF_OR_NAN(area) || area == 0.0F)
if (area * bf * swrast->_BackfaceCullSign < 0.0)
return;
oneOverArea = 1.0F / area;
/* 0 = front, 1 = back */
span.facing = oneOverArea * swrast->_BackfaceSign > 0.0F;
span.facing = oneOverArea * bf > 0.0F;
}
/* Edge setup. For a triangle strip these could be reused... */