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Different integer overflow test for zbuffering, this due to mist+wire bug

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that seems not to be solved on intel platforms.

Previously, a positive signed integer overflow addition was checked by
assuming it to become negative. Now it checks 'safe' with this version:

if(vergz > 0x7FFFFFF0 - dz) vergz= 0x7FFFFFF0;
else vergz+= dz;

Reason why using signed ints is cumbersome... overflows for unsigned are
much easer to find.
This commit is contained in:
Ton Roosendaal
2005-01-09 13:36:14 +00:00
parent 4f2e57a541
commit 8229ea59de
2 changed files with 14 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
source/blender/render/intern/source/rendercore.c
View File

@@ -118,7 +118,7 @@ float mistfactor(float zcor, float *co) /* dist en height, return alpha */
}
}
return (1.0-fac)* (1-R.wrld.misi);
return (1.0-fac)* (1.0-R.wrld.misi);
}
/* external for preview only */

25
source/blender/render/intern/source/zbuf.c
View File

@@ -513,7 +513,7 @@ void zbuflineAc(int zvlnr, float *vec1, float *vec2)
vergz= v1[2];
vergz-= Azvoordeel;
dz= (v2[2]-v1[2])/dx;
if(vergz>0x70000000 && dz>0) maxtest= 1; // prevent overflow
if(vergz>0x50000000 && dz>0) maxtest= 1; // prevent overflow
rectz= (int *)(Arectz+R.rectx*(oldy-Aminy) +start);
ap= (APixbuf+ R.rectx*(oldy-Aminy) +start);
@@ -552,8 +552,8 @@ void zbuflineAc(int zvlnr, float *vec1, float *vec2)
}
v1[1]+= dy;
vergz+= dz;
if(maxtest && vergz<0) vergz= 0x7FFFFFF0;
if(maxtest && (vergz > 0x7FFFFFF0 - dz)) vergz= 0x7FFFFFF0;
else vergz+= dz;
}
}
else {
@@ -582,7 +582,7 @@ void zbuflineAc(int zvlnr, float *vec1, float *vec2)
vergz= v1[2];
vergz-= Azvoordeel;
dz= (v2[2]-v1[2])/dy;
if(vergz>0x70000000 && dz>0) maxtest= 1; // prevent overflow
if(vergz>0x50000000 && dz>0) maxtest= 1; // prevent overflow
rectz= (int *)( Arectz+ (start-Aminy)*R.rectx+ oldx );
ap= (APixbuf+ R.rectx*(start-Aminy) +oldx);
@@ -621,8 +621,8 @@ void zbuflineAc(int zvlnr, float *vec1, float *vec2)
}
v1[0]+= dx;
vergz+= dz;
if(maxtest && vergz<0) vergz= 0x7FFFFFF0;
if(maxtest && (vergz > 0x7FFFFFF0 - dz)) vergz= 0x7FFFFFF0;
else vergz+= dz;
}
}
}
@@ -683,7 +683,7 @@ void zbufline(int zvlnr, float *vec1, float *vec2)
vergz= floor(v1[2]);
dz= floor((v2[2]-v1[2])/dx);
if(vergz>0x70000000 && dz>0) maxtest= 1; // prevent overflow
if(vergz>0x50000000 && dz>0) maxtest= 1; // prevent overflow
rectz= R.rectz+ oldy*R.rectx+ start;
rectp= R.rectot+ oldy*R.rectx+ start;
@@ -708,8 +708,9 @@ void zbufline(int zvlnr, float *vec1, float *vec2)
}
v1[1]+= dy;
vergz+= dz;
if(maxtest && vergz<0) vergz= 0x7FFFFFF0;
if(maxtest && (vergz > 0x7FFFFFF0 - dz)) vergz= 0x7FFFFFF0;
else vergz+= dz;
}
}
else {
@@ -734,7 +735,7 @@ void zbufline(int zvlnr, float *vec1, float *vec2)
vergz= floor(v1[2]);
dz= floor((v2[2]-v1[2])/dy);
if(vergz>0x70000000 && dz>0) maxtest= 1; // prevent overflow
if(vergz>0x50000000 && dz>0) maxtest= 1; // prevent overflow
rectz= R.rectz+ start*R.rectx+ oldx;
rectp= R.rectot+ start*R.rectx+ oldx;
@@ -759,8 +760,8 @@ void zbufline(int zvlnr, float *vec1, float *vec2)
}
v1[0]+= dx;
vergz+= dz;
if(maxtest && vergz<0) vergz= 0x7FFFFFF0;
if(maxtest && (vergz > 0x7FFFFFF0 - dz)) vergz= 0x7FFFFFF0;
else vergz+= dz;
}
}
}