Cleanup: Move SpaceTransform helpers from `BKE_shrinkwrap` to `BLI_math_matrix`.

2 files changed, 64 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_math_matrix.h b/source/blender/blenlib/BLI_math_matrix.h
index 68d8e3b9499..7bcaab1f939 100644
--- a/source/blender/blenlib/BLI_math_matrix.h
+++ b/source/blender/blenlib/BLI_math_matrix.h
@@ -224,6 +224,22 @@ bool is_negative_m4(float mat[4][4]);
 bool is_zero_m3(float mat[3][3]);
 bool is_zero_m4(float mat[4][4]);
 
+/* SpaceTransform helper */
+typedef struct SpaceTransform {
+	float local2target[4][4];
+	float target2local[4][4];
+
+} SpaceTransform;
+
+void BLI_space_transform_from_matrices(struct SpaceTransform *data, float local[4][4], float target[4][4]);
+void BLI_space_transform_apply(const struct SpaceTransform *data, float co[3]);
+void BLI_space_transform_invert(const struct SpaceTransform *data, float co[3]);
+void BLI_space_transform_apply_normal(const struct SpaceTransform *data, float no[3]);
+void BLI_space_transform_invert_normal(const struct SpaceTransform *data, float no[3]);
+
+#define BLI_SPACE_TRANSFORM_SETUP(data, local, target) \
+	BLI_space_transform_from_matrices((data), (local)->obmat, (target)->obmat)
+
 /*********************************** Other ***********************************/
 
 void print_m3(const char *str, float M[3][3]);
diff --git a/source/blender/blenlib/intern/math_matrix.c b/source/blender/blenlib/intern/math_matrix.c
index 54bee803f9c..152b31754bb 100644
--- a/source/blender/blenlib/intern/math_matrix.c
+++ b/source/blender/blenlib/intern/math_matrix.c
@@ -2215,3 +2215,51 @@ void invert_m4_m4_safe(float Ainv[4][4], float A[4][4])
 		}
 	}
 }
+
+/**
+ * SpaceTransform struct encapsulates all needed data to convert between two coordinate spaces
+ * (where conversion can be represented by a matrix multiplication).
+ *
+ * A SpaceTransform is initialized using:
+ *   BLI_SPACE_TRANSFORM_SETUP(&data,  ob1, ob2)
+ *
+ * After that the following calls can be used:
+ *   BLI_space_transform_apply(&data, co);  // converts a coordinate in ob1 space to the corresponding ob2 space
+ *   BLI_space_transform_invert(&data, co);  // converts a coordinate in ob2 space to the corresponding ob1 space
+ *
+ * Same concept as BLI_space_transform_apply and BLI_space_transform_invert, but no is normalized after conversion
+ * (and not translated at all!):
+ *   BLI_space_transform_apply_normal(&data, no);
+ *   BLI_space_transform_invert_normal(&data, no);
+ *
+ */
+
+void BLI_space_transform_from_matrices(SpaceTransform *data, float local[4][4], float target[4][4])
+{
+	float itarget[4][4];
+	invert_m4_m4(itarget, target);
+	mul_m4_m4m4(data->local2target, itarget, local);
+	invert_m4_m4(data->target2local, data->local2target);
+}
+
+void BLI_space_transform_apply(const SpaceTransform *data, float co[3])
+{
+	mul_v3_m4v3(co, ((SpaceTransform *)data)->local2target, co);
+}
+
+void BLI_space_transform_invert(const SpaceTransform *data, float co[3])
+{
+	mul_v3_m4v3(co, ((SpaceTransform *)data)->target2local, co);
+}
+
+void BLI_space_transform_apply_normal(const SpaceTransform *data, float no[3])
+{
+	mul_mat3_m4_v3(((SpaceTransform *)data)->local2target, no);
+	normalize_v3(no);
+}
+
+void BLI_space_transform_invert_normal(const SpaceTransform *data, float no[3])
+{
+	mul_mat3_m4_v3(((SpaceTransform *)data)->target2local, no);
+	normalize_v3(no);
+}