Previous fix for stabilization autoscale actually broke stabilizaiton itself

(median point was sliding a bit from it's original position)

This happens because of how transformation for stabilization calculates:
image is scaling around it's center, so image translation should be recalculated
after scale was changed, but scale also depends on translation. That's where
tricky things happens. It's still not ideal for case of rotation, but before
fixing this issue better to figure out usecase and see if it's indeed
so needed to scale around image center (it might only be helpful to use
stabilization parameters in compositor nodes).

1 files changed, 28 insertions, 42 deletions

diff --git a/source/blender/blenkernel/intern/tracking.c b/source/blender/blenkernel/intern/tracking.c
index 5a7a11cd0cc..454e6fa82fa 100644
--- a/source/blender/blenkernel/intern/tracking.c
+++ b/source/blender/blenkernel/intern/tracking.c
@@ -2451,8 +2451,8 @@ static void calculate_stabdata(MovieTracking *tracking, int framenr, float width
 	*scale= (stab->scale-1.0f)*stab->scaleinf+1.0f;
 	*angle= 0.0f;
 
-	loc[0]= (firstmedian[0]-median[0])*width;
-	loc[1]= (firstmedian[1]-median[1])*height;
+	loc[0]= (firstmedian[0]-median[0])*width*(*scale);
+	loc[1]= (firstmedian[1]-median[1])*height*(*scale);
 
 	mul_v2_fl(loc, stab->locinf);
 
@@ -2492,7 +2492,7 @@ static float stabilization_auto_scale_factor(MovieTracking *tracking, int width,
 
 	if(stabilization_median_point(tracking, 1, firstmedian)) {
 		int sfra= INT_MAX, efra= INT_MIN, cfra;
-		float delta[2]= {0.0f, 0.0f}, scalex= 1.0f, scaley= 1.0f;
+		float scalex= 1.0f, scaley= 1.0f;
 		MovieTrackingTrack *track;
 
 		stab->scale= 1.0f;
@@ -2509,59 +2509,45 @@ static float stabilization_auto_scale_factor(MovieTracking *tracking, int width,
 		}
 
 		for(cfra=sfra; cfra<=efra; cfra++) {
-			float median[2], near[2];
+			float median[2];
 			float loc[2], scale, angle;
+			int i;
+			float mat[4][4];
+			float points[4][2]={{0.0f, 0.0f}, {0.0f, height}, {width, height}, {width, 0.0f}};
 
 			stabilization_median_point(tracking, cfra, median);
 
 			calculate_stabdata(tracking, cfra, width, height, firstmedian, median,
 						loc, &scale, &angle);
 
-			if(angle==0.0f) {
-				loc[0]= fabsf(loc[0]);
-				loc[1]= fabsf(loc[1]);
-
-				delta[0]= MAX2(delta[0], loc[0]);
-				delta[1]= MAX2(delta[1], loc[1]);
-
-				near[0]= MIN2(median[0], 1.0f-median[0]);
-				near[1]= MIN2(median[1], 1.0f-median[1]);
-				near[0]= MAX2(near[0], 0.05f);
-				near[1]= MAX2(near[1], 0.05f);
-
-				scalex= 1.0f+delta[0]/(near[0]*width);
-				scaley= 1.0f+delta[1]/(near[1]*height);
-			} else {
-				int i;
-				float mat[4][4];
-				float points[4][2]={{0.0f, 0.0f}, {0.0f, height}, {width, height}, {width, 0.0f}};
+			BKE_tracking_stabdata_to_mat4(width, height, aspect, loc, scale, angle, mat);
 
-				BKE_tracking_stabdata_to_mat4(width, height, aspect, loc, scale, angle, mat);
+			for(i= 0; i<4; i++) {
+				int j;
+				float a[3]= {0.0f, 0.0f, 0.0f}, b[3]= {0.0f, 0.0f, 0.0f};
 
-				for(i= 0; i<4; i++) {
-					int j;
-					float a[3]= {0.0f, 0.0f, 0.0f}, b[3]= {0.0f, 0.0f, 0.0f};
+				copy_v3_v3(a, points[i]);
+				copy_v3_v3(b, points[(i+1)%4]);
 
-					copy_v3_v3(a, points[i]);
-					copy_v3_v3(b, points[(i+1)%4]);
+				mul_m4_v3(mat, a);
+				mul_m4_v3(mat, b);
 
-					mul_m4_v3(mat, a);
-					mul_m4_v3(mat, b);
+				for(j= 0; j<4; j++) {
+					float point[3]= {points[j][0], points[j][1], 0.0f};
+					float v1[3], v2[3];
 
-					for(j= 0; j<4; j++) {
-						float point[3]= {points[j][0], points[j][1], 0.0f};
-						float v1[3], v2[3];
+					sub_v3_v3v3(v1, b, a);
+					sub_v3_v3v3(v2, point, a);
 
-						sub_v3_v3v3(v1, b, a);
-						sub_v3_v3v3(v2, point, a);
+					if(cross_v2v2(v1, v2) >= 0.0f) {
+						float dist= dist_to_line_v2(point, a, b), cur_scale;
 
-						if(cross_v2v2(v1, v2) >= 0.0f) {
-							float dist= dist_to_line_v2(point, a, b);
-							if(i%2==0) {
-								scalex= MAX2(scalex, (width+2*dist)/width);
-							} else {
-								scaley= MAX2(scaley, (height+2*dist)/height);
-							}
+						if(i%2==0) {
+							cur_scale= 0.5f * (float)width / (0.5f * (float)width - dist);
+							scalex= MAX2(scalex, cur_scale);
+						} else {
+							cur_scale= 0.5f * (float)height / (0.5f * (float)height - dist);
+							scaley= MAX2(scaley, cur_scale);
 						}
 					}
 				}