diff options
| -rw-r--r-- | src/mesa/swrast/s_tritemp.h | 91 |
1 files changed, 56 insertions, 35 deletions
diff --git a/src/mesa/swrast/s_tritemp.h b/src/mesa/swrast/s_tritemp.h index 142bd0992e5..f1dc91bd967 100644 --- a/src/mesa/swrast/s_tritemp.h +++ b/src/mesa/swrast/s_tritemp.h @@ -1,4 +1,4 @@ -/* $Id: s_tritemp.h,v 1.17 2001/05/16 20:27:12 brianp Exp $ */ +/* $Id: s_tritemp.h,v 1.18 2001/06/12 14:18:58 brianp Exp $ */ /* * Mesa 3-D graphics library @@ -95,6 +95,8 @@ const SWvertex *vMin, *vMid, *vMax; /* Y(vMin)<=Y(vMid)<=Y(vMax) */ float bf = SWRAST_CONTEXT(ctx)->_backface_sign; GLboolean tiny; + const GLint snapMask = ~((FIXED_ONE / 16) - 1); /* for x/y coord snapping */ + GLfixed vMin_fx, vMin_fy, vMid_fx, vMid_fy, vMax_fx, vMax_fy; struct triangle_span span; @@ -102,34 +104,56 @@ (void) fixedToDepthShift; #endif - /* find the order of the 3 vertices along the Y axis */ + /* Compute fixed point x,y coords w/ half-pixel offsets and snapping. + * And find the order of the 3 vertices along the Y axis. + */ { - GLfloat y0 = v0->win[1]; - GLfloat y1 = v1->win[1]; - GLfloat y2 = v2->win[1]; - - if (y0<=y1) { - if (y1<=y2) { - vMin = v0; vMid = v1; vMax = v2; /* y0<=y1<=y2 */ + const GLfixed fy0 = FloatToFixed(v0->win[1] + 0.5F) & snapMask; + const GLfixed fy1 = FloatToFixed(v1->win[1] + 0.5F) & snapMask; + const GLfixed fy2 = FloatToFixed(v2->win[1] + 0.5F) & snapMask; + + if (fy0 <= fy1) { + if (fy1 <= fy2) { + /* y0 <= y1 <= y2 */ + vMin = v0; vMid = v1; vMax = v2; + vMin_fy = fy0; vMid_fy = fy1; vMax_fy = fy2; } - else if (y2<=y0) { - vMin = v2; vMid = v0; vMax = v1; /* y2<=y0<=y1 */ + else if (fy2 <= fy0) { + /* y2 <= y0 <= y1 */ + vMin = v2; vMid = v0; vMax = v1; + vMin_fy = fy2; vMid_fy = fy0; vMax_fy = fy1; } else { - vMin = v0; vMid = v2; vMax = v1; bf = -bf; /* y0<=y2<=y1 */ + /* y0 <= y2 <= y1 */ + vMin = v0; vMid = v2; vMax = v1; + vMin_fy = fy0; vMid_fy = fy2; vMax_fy = fy1; + bf = -bf; } } else { - if (y0<=y2) { - vMin = v1; vMid = v0; vMax = v2; bf = -bf; /* y1<=y0<=y2 */ + if (fy0 <= fy2) { + /* y1 <= y0 <= y2 */ + vMin = v1; vMid = v0; vMax = v2; + vMin_fy = fy1; vMid_fy = fy0; vMax_fy = fy2; + bf = -bf; } - else if (y2<=y1) { - vMin = v2; vMid = v1; vMax = v0; bf = -bf; /* y2<=y1<=y0 */ + else if (fy2 <= fy1) { + /* y2 <= y1 <= y0 */ + vMin = v2; vMid = v1; vMax = v0; + vMin_fy = fy2; vMid_fy = fy1; vMax_fy = fy0; + bf = -bf; } else { - vMin = v1; vMid = v2; vMax = v0; /* y1<=y2<=y0 */ + /* y1 <= y2 <= y0 */ + vMin = v1; vMid = v2; vMax = v0; + vMin_fy = fy1; vMid_fy = fy2; vMax_fy = fy0; } } + + /* fixed point X coords */ + vMin_fx = FloatToFixed(vMin->win[0] + 0.5F) & snapMask; + vMid_fx = FloatToFixed(vMid->win[0] + 0.5F) & snapMask; + vMax_fx = FloatToFixed(vMax->win[0] + 0.5F) & snapMask; } /* vertex/edge relationship */ @@ -137,15 +161,15 @@ eTop.v0 = vMid; eTop.v1 = vMax; eBot.v0 = vMin; eBot.v1 = vMid; - /* compute deltas for each edge: vertex[v1] - vertex[v0] */ - eMaj.dx = vMax->win[0] - vMin->win[0]; - eMaj.dy = vMax->win[1] - vMin->win[1]; - eTop.dx = vMax->win[0] - vMid->win[0]; - eTop.dy = vMax->win[1] - vMid->win[1]; - eBot.dx = vMid->win[0] - vMin->win[0]; - eBot.dy = vMid->win[1] - vMin->win[1]; + /* compute deltas for each edge: vertex[upper] - vertex[lower] */ + eMaj.dx = FixedToFloat(vMax_fx - vMin_fx); + eMaj.dy = FixedToFloat(vMax_fy - vMin_fy); + eTop.dx = FixedToFloat(vMax_fx - vMid_fx); + eTop.dy = FixedToFloat(vMax_fy - vMid_fy); + eBot.dx = FixedToFloat(vMid_fx - vMin_fx); + eBot.dy = FixedToFloat(vMid_fy - vMin_fy); - /* compute oneOverArea */ + /* compute area, oneOverArea and perform backface culling */ { const GLfloat area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy; @@ -156,12 +180,16 @@ if (area == 0.0F) return; + /* This may not be needed anymore. Let's see if anyone reports a problem. */ +#if 0 /* check for very tiny triangle */ - if (area * area < (0.05F * 0.05F)) { /* square to ensure positive value */ - oneOverArea = 1.0F / 0.05F; /* a close-enough value */ + if (area * area < (0.001F * 0.001F)) { /* square to ensure positive value */ + oneOverArea = 1.0F / 0.001F; /* a close-enough value */ tiny = GL_TRUE; } - else { + else +#endif + { oneOverArea = 1.0F / area; tiny = GL_FALSE; } @@ -173,13 +201,6 @@ /* Edge setup. For a triangle strip these could be reused... */ { - /* fixed point Y coordinates */ - GLfixed vMin_fx = FloatToFixed(vMin->win[0] + 0.5F); - GLfixed vMin_fy = FloatToFixed(vMin->win[1] - 0.5F); - GLfixed vMid_fx = FloatToFixed(vMid->win[0] + 0.5F); - GLfixed vMid_fy = FloatToFixed(vMid->win[1] - 0.5F); - GLfixed vMax_fy = FloatToFixed(vMax->win[1] - 0.5F); - eMaj.fsy = FixedCeil(vMin_fy); eMaj.lines = FixedToInt(FixedCeil(vMax_fy - eMaj.fsy)); if (eMaj.lines > 0) { |