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Fix T86889: Rotation with top plane view glitches 

The `InputAngle` function uses a flawed algorithm to fix precision issues.

This commit refactor the logic of that function by using BLI utilities.

Differential Revision: https://developer.blender.org/D10880
This commit is contained in:
Germano Cavalcante 2021-04-06 09:55:00 -03:00 committed by Germano Cavalcante
parent 24d71acd86
commit 490801ba1d
Notes: blender-bot 2023-02-14 10:18:56 +01:00 
Referenced by issue #86889, Rotation with top plane view glitches
1 changed files with 12 additions and 45 deletions
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57
source/blender/editors/transform/transform_input.c
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@ -186,58 +186,25 @@ struct InputAngle_Data {
static void InputAngle(TransInfo *UNUSED(t), MouseInput *mi, const double mval[2], float output[3])
{
struct InputAngle_Data *data = mi->data;
double dx2 = mval[0] - (double)mi->center[0];
double dy2 = mval[1] - (double)mi->center[1];
double B = sqrt(dx2 * dx2 + dy2 * dy2);
float dir_prev[2], dir_curr[2], mi_center[2];
copy_v2_v2(mi_center, mi->center);
double dx1 = data->mval_prev[0] - (double)mi->center[0];
double dy1 = data->mval_prev[1] - (double)mi->center[1];
double A = sqrt(dx1 * dx1 + dy1 * dy1);
sub_v2_v2v2(dir_prev, (const float[2]){UNPACK2(data->mval_prev)}, mi_center);
sub_v2_v2v2(dir_curr, (const float[2]){UNPACK2(mval)}, mi_center);
double dx3 = mval[0] - data->mval_prev[0];
double dy3 = mval[1] - data->mval_prev[1];
if (normalize_v2(dir_prev) && normalize_v2(dir_curr)) {
float dphi = angle_normalized_v2v2(dir_prev, dir_curr);
/* use doubles here, to make sure a "1.0" (no rotation)
* doesn't become 9.999999e-01, which gives 0.02 for acos */
double deler = (((dx1 * dx1 + dy1 * dy1) + (dx2 * dx2 + dy2 * dy2) - (dx3 * dx3 + dy3 * dy3)) /
(2.0 * (((A * B) != 0.0) ? (A * B) : 1.0)));
/* ((A * B) ? (A * B) : 1.0) this takes care of potential divide by zero errors */
float dphi;
dphi = saacos((float)deler);
if ((dx1 * dy2 - dx2 * dy1) > 0.0) {
dphi = -dphi;
}
/* If the angle is zero, because of lack of precision close to the 1.0 value in acos
* approximate the angle with the opposite side of the normalized triangle
* This is a good approximation here since the smallest acos value seems to be around
* 0.02 degree and lower values don't even have a 0.01% error compared to the approximation
*/
if (dphi == 0) {
double dx, dy;
dx2 /= A;
dy2 /= A;
dx1 /= B;
dy1 /= B;
dx = dx1 - dx2;
dy = dy1 - dy2;
dphi = sqrt(dx * dx + dy * dy);
if ((dx1 * dy2 - dx2 * dy1) > 0.0) {
if (cross_v2v2(dir_prev, dir_curr) > 0.0f) {
dphi = -dphi;
}
data->angle += ((double)dphi) * (mi->precision ? (double)mi->precision_factor : 1.0);
data->mval_prev[0] = mval[0];
data->mval_prev[1] = mval[1];
}
data->angle += ((double)dphi) * (mi->precision ? (double)mi->precision_factor : 1.0);
data->mval_prev[0] = mval[0];
data->mval_prev[1] = mval[1];
output[0] = data->angle;
}