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Fix rounding issues in _glClipLineToNearZ

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This commit is contained in:
Luke Benstead 2020-03-28 16:46:43 +00:00
parent 9c47f3c3bb
commit 0e26d8656d
1 changed files with 18 additions and 9 deletions
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27
GL/clip.c
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@ -27,17 +27,24 @@ inline float _glClipLineToNearZ(const Vertex* v1, const Vertex* v2, Vertex* vout
const float d0 = v1->w + v1->xyz[2];
const float d1 = v2->w + v2->xyz[2];
float t = d0 / (d0 - d1);
/* We need to shift 't' a little, to avoid the possibility that a
* rounding error leaves the new vertex behind the near plane. We shift
* according to the direction we're clipping across the plane */
const float epsilon = (d0 < d1) ? -0.000001 : 0.000001;
const float vec [] = {
v2->xyz[0] - v1->xyz[0],
v2->xyz[1] - v1->xyz[1],
v2->xyz[2] - v1->xyz[2]
};
float t = MATH_Fast_Divide(d0, (d0 - d1)) + epsilon;
vout->xyz[0] = MATH_fmac(vec[0], t, v1->xyz[0]);
vout->xyz[1] = MATH_fmac(vec[1], t, v1->xyz[1]);
vout->xyz[2] = MATH_fmac(vec[2], t, v1->xyz[2]);
vout->xyz[0] = MATH_fmac(v2->xyz[0] - v1->xyz[0], t, v1->xyz[0]);
vout->xyz[1] = MATH_fmac(v2->xyz[1] - v1->xyz[1], t, v1->xyz[1]);
vout->xyz[2] = MATH_fmac(v2->xyz[2] - v1->xyz[2], t, v1->xyz[2]);
/*
printf(
"(%f, %f, %f, %f) -> %f -> (%f, %f, %f, %f) = (%f, %f, %f)\n",
v1->xyz[0], v1->xyz[1], v1->xyz[2], v1->w, t,
v2->xyz[0], v2->xyz[1], v2->xyz[2], v2->w,
vout->xyz[0], vout->xyz[1], vout->xyz[2]
);*/
return t;
}
@ -261,6 +268,8 @@ void _glClipTriangleStrip(SubmissionTarget* target, uint8_t fladeShade) {
((v3->w > 0 && v3->xyz[2] >= -v3->w) ? 1 : 0)
);
printf("Visible: %d\n", visible);
switch(visible) {
case B111:
/* All visible? Do nothing */