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Exclude last row in rasterization

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Miloslav Číž 2019-05-05 16:47:08 +02:00
parent 0a27bbe2b5
commit d585310b97
1 changed files with 8 additions and 5 deletions
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13
s3l.h
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@ -94,9 +94,9 @@
transformation to triangle A first and then rasterizing it. Even the number transformation to triangle A first and then rasterizing it. Even the number
of rasterized pixels is usually different. of rasterized pixels is usually different.
- If specifying a triangle with integer coordinates, then: - If specifying a triangle with integer coordinates, then:
- a Bottom-most corner (or side) of a triangle is never rasterized (because - The bottom-most corner (or side) of a triangle is never rasterized
it is connected to a right side). (because it is connected to a right side).
- Top-most corner can only be rasterized on completely horizontal side - The top-most corner can only be rasterized on completely horizontal side
(otherwise it is connected to a right side). (otherwise it is connected to a right side).
- Vertically middle corner is rasterized if and only if it is on the left - Vertically middle corner is rasterized if and only if it is on the left
of the triangle and at the same time is also not the bottom-most corner. of the triangle and at the same time is also not the bottom-most corner.
@ -791,7 +791,7 @@ void S3L_drawTriangle(
infinite substracting loop */ infinite substracting loop */
#define stepSide(s)\ #define stepSide(s)\
while (s##Err > s##Dy)\ while (s##Err >= s##Dy)\
{\ {\
s##X += s##Inc;\ s##X += s##Inc;\
s##Err -= s##ErrSub;\ s##Err -= s##ErrSub;\
@ -801,7 +801,10 @@ void S3L_drawTriangle(
initSide(r,t,r,1,1) initSide(r,t,r,1,1)
initSide(l,t,l,1,0) initSide(l,t,l,1,0)
while (currentY <= endY) // draw the triangle from top to bottom while (currentY < endY) /* draw the triangle from top to bottom -- the
bottom-most row is left out because, following
from the rasterization rules (see top of the
source), it is to never be rasterized. */
{ {
if (currentY == splitY) // reached a vertical split of the triangle? if (currentY == splitY) // reached a vertical split of the triangle?
{ // then reinit one side { // then reinit one side