convert old octahedral compressed normals/tangents

1 files changed, 136 insertions, 48 deletions

diff --git a/scene/resources/mesh.cpp b/scene/resources/mesh.cpp
index 661016d148..9e654f0cce 100644
--- a/scene/resources/mesh.cpp
+++ b/scene/resources/mesh.cpp
@@ -596,7 +596,7 @@ enum OldArrayFormat {
 	OLD_ARRAY_FLAG_USE_2D_VERTICES = OLD_ARRAY_COMPRESS_INDEX << 1,
 	OLD_ARRAY_FLAG_USE_16_BIT_BONES = OLD_ARRAY_COMPRESS_INDEX << 2,
 	OLD_ARRAY_FLAG_USE_DYNAMIC_UPDATE = OLD_ARRAY_COMPRESS_INDEX << 3,
-
+	OLD_ARRAY_FLAG_USE_OCTAHEDRAL_COMPRESSION = OLD_ARRAY_COMPRESS_INDEX << 4,
 };
 
 #ifndef DISABLE_DEPRECATED
@@ -626,6 +626,27 @@ static Mesh::PrimitiveType _old_primitives[7] = {
 };
 #endif // DISABLE_DEPRECATED
 
+// Convert Octahedron-mapped normalized vector back to Cartesian
+// Assumes normalized format (elements of v within range [-1, 1])
+Vector3 _oct_to_norm(const Vector2 v) {
+	Vector3 res(v.x, v.y, 1 - (Math::absf(v.x) + Math::absf(v.y)));
+	float t = MAX(-res.z, 0.0f);
+	res.x += t * -SIGN(res.x);
+	res.y += t * -SIGN(res.y);
+	return res.normalized();
+}
+
+// Convert Octahedron-mapped normalized tangent vector back to Cartesian
+// out_sign provides the direction for the original cartesian tangent
+// Assumes normalized format (elements of v within range [-1, 1])
+Vector3 _oct_to_tangent(const Vector2 v, float *out_sign) {
+	Vector2 v_decompressed = v;
+	v_decompressed.y = Math::absf(v_decompressed.y) * 2 - 1;
+	Vector3 res = _oct_to_norm(v_decompressed);
+	*out_sign = SIGN(v[1]);
+	return res;
+}
+
 void _fix_array_compatibility(const Vector<uint8_t> &p_src, uint32_t p_old_format, uint32_t p_new_format, uint32_t p_elements, Vector<uint8_t> &vertex_data, Vector<uint8_t> &attribute_data, Vector<uint8_t> &skin_data) {
 	uint32_t dst_vertex_stride;
 	uint32_t dst_attribute_stride;
@@ -692,66 +713,133 @@ void _fix_array_compatibility(const Vector<uint8_t> &p_src, uint32_t p_old_forma
 				}
 			} break;
 			case OLD_ARRAY_NORMAL: {
-				if (p_old_format & OLD_ARRAY_COMPRESS_NORMAL) {
-					const float multiplier = 1.f / 127.f * 1023.0f;
+				if (p_old_format & OLD_ARRAY_FLAG_USE_OCTAHEDRAL_COMPRESSION) {
+					if ((p_old_format & OLD_ARRAY_COMPRESS_NORMAL) && (p_old_format & OLD_ARRAY_FORMAT_TANGENT) && (p_old_format & OLD_ARRAY_COMPRESS_TANGENT)) {
+						for (uint32_t i = 0; i < p_elements; i++) {
+							const int8_t *src = (const int8_t *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
+							uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_NORMAL]];
+							const Vector2 src_vec(src[0] / 127.0f, src[1] / 127.0f);
+
+							const Vector3 res = _oct_to_norm(src_vec) * Vector3(0.5, 0.5, 0.5) + Vector3(0.5, 0.5, 0.5);
+							*dst = 0;
+							*dst |= CLAMP(int(res.x * 1023.0f), 0, 1023);
+							*dst |= CLAMP(int(res.y * 1023.0f), 0, 1023) << 10;
+							*dst |= CLAMP(int(res.z * 1023.0f), 0, 1023) << 20;
+						}
+						src_offset += sizeof(int8_t) * 2;
+					} else {
+						for (uint32_t i = 0; i < p_elements; i++) {
+							const int16_t *src = (const int16_t *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
+							uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_NORMAL]];
+							const Vector2 src_vec(src[0] / 32767.0f, src[1] / 32767.0f);
+
+							const Vector3 res = _oct_to_norm(src_vec) * Vector3(0.5, 0.5, 0.5) + Vector3(0.5, 0.5, 0.5);
+							*dst = 0;
+							*dst |= CLAMP(int(res.x * 1023.0f), 0, 1023);
+							*dst |= CLAMP(int(res.y * 1023.0f), 0, 1023) << 10;
+							*dst |= CLAMP(int(res.z * 1023.0f), 0, 1023) << 20;
+						}
+						src_offset += sizeof(int16_t) * 2;
+					}
+				} else { // No Octahedral compression
+					if (p_old_format & OLD_ARRAY_COMPRESS_NORMAL) {
+						const float multiplier = 1.f / 127.f * 1023.0f;
 
-					for (uint32_t i = 0; i < p_elements; i++) {
-						const int8_t *src = (const int8_t *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
-						uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_NORMAL]];
+						for (uint32_t i = 0; i < p_elements; i++) {
+							const int8_t *src = (const int8_t *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
+							uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_NORMAL]];
 
-						*dst = 0;
-						*dst |= CLAMP(int(src[0] * multiplier), 0, 1023);
-						*dst |= CLAMP(int(src[1] * multiplier), 0, 1023) << 10;
-						*dst |= CLAMP(int(src[2] * multiplier), 0, 1023) << 20;
-					}
-					src_offset += sizeof(uint32_t);
-				} else {
-					for (uint32_t i = 0; i < p_elements; i++) {
-						const float *src = (const float *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
-						uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_NORMAL]];
+							*dst = 0;
+							*dst |= CLAMP(int(src[0] * multiplier), 0, 1023);
+							*dst |= CLAMP(int(src[1] * multiplier), 0, 1023) << 10;
+							*dst |= CLAMP(int(src[2] * multiplier), 0, 1023) << 20;
+						}
+						src_offset += sizeof(uint32_t);
+					} else {
+						for (uint32_t i = 0; i < p_elements; i++) {
+							const float *src = (const float *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
+							uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_NORMAL]];
 
-						*dst = 0;
-						*dst |= CLAMP(int(src[0] * 1023.0), 0, 1023);
-						*dst |= CLAMP(int(src[1] * 1023.0), 0, 1023) << 10;
-						*dst |= CLAMP(int(src[2] * 1023.0), 0, 1023) << 20;
+							*dst = 0;
+							*dst |= CLAMP(int(src[0] * 1023.0), 0, 1023);
+							*dst |= CLAMP(int(src[1] * 1023.0), 0, 1023) << 10;
+							*dst |= CLAMP(int(src[2] * 1023.0), 0, 1023) << 20;
+						}
+						src_offset += sizeof(float) * 3;
 					}
-					src_offset += sizeof(float) * 3;
 				}
 
 			} break;
 			case OLD_ARRAY_TANGENT: {
-				if (p_old_format & OLD_ARRAY_COMPRESS_TANGENT) {
-					const float multiplier = 1.f / 127.f * 1023.0f;
-
-					for (uint32_t i = 0; i < p_elements; i++) {
-						const int8_t *src = (const int8_t *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
-						uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_TANGENT]];
-
-						*dst = 0;
-						*dst |= CLAMP(int(src[0] * multiplier), 0, 1023);
-						*dst |= CLAMP(int(src[1] * multiplier), 0, 1023) << 10;
-						*dst |= CLAMP(int(src[2] * multiplier), 0, 1023) << 20;
-						if (src[3] > 0) {
-							*dst |= 3 << 30;
+				if (p_old_format & OLD_ARRAY_FLAG_USE_OCTAHEDRAL_COMPRESSION) {
+					if (p_old_format & OLD_ARRAY_COMPRESS_TANGENT) { // int8
+						for (uint32_t i = 0; i < p_elements; i++) {
+							const int8_t *src = (const int8_t *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
+							uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_TANGENT]];
+							const Vector2 src_vec(src[0] / 127.0f, src[1] / 127.0f);
+							float out_sign;
+							const Vector3 res = _oct_to_tangent(src_vec, &out_sign) * Vector3(0.5, 0.5, 0.5) + Vector3(0.5, 0.5, 0.5);
+
+							*dst = 0;
+							*dst |= CLAMP(int(res.x * 1023.0), 0, 1023);
+							*dst |= CLAMP(int(res.y * 1023.0), 0, 1023) << 10;
+							*dst |= CLAMP(int(res.z * 1023.0), 0, 1023) << 20;
+							if (out_sign > 0) {
+								*dst |= 3 << 30;
+							}
 						}
+						src_offset += sizeof(int8_t) * 2;
+					} else { // int16
+						for (uint32_t i = 0; i < p_elements; i++) {
+							const int16_t *src = (const int16_t *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
+							uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_TANGENT]];
+							const Vector2 src_vec(src[0] / 32767.0f, src[1] / 32767.0f);
+							float out_sign;
+							Vector3 res = _oct_to_tangent(src_vec, &out_sign) * Vector3(0.5, 0.5, 0.5) + Vector3(0.5, 0.5, 0.5);
+
+							*dst = 0;
+							*dst |= CLAMP(int(res.x * 1023.0), 0, 1023);
+							*dst |= CLAMP(int(res.y * 1023.0), 0, 1023) << 10;
+							*dst |= CLAMP(int(res.z * 1023.0), 0, 1023) << 20;
+							if (out_sign > 0) {
+								*dst |= 3 << 30;
+							}
+						}
+						src_offset += sizeof(int16_t) * 2;
 					}
-					src_offset += sizeof(uint32_t);
-				} else {
-					for (uint32_t i = 0; i < p_elements; i++) {
-						const float *src = (const float *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
-						uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_TANGENT]];
-
-						*dst = 0;
-						*dst |= CLAMP(int(src[0] * 1023.0), 0, 1023);
-						*dst |= CLAMP(int(src[1] * 1023.0), 0, 1023) << 10;
-						*dst |= CLAMP(int(src[2] * 1023.0), 0, 1023) << 20;
-						if (src[3] > 0) {
-							*dst |= 3 << 30;
+				} else { // No Octahedral compression
+					if (p_old_format & OLD_ARRAY_COMPRESS_TANGENT) {
+						const float multiplier = 1.f / 127.f * 1023.0f;
+
+						for (uint32_t i = 0; i < p_elements; i++) {
+							const int8_t *src = (const int8_t *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
+							uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_TANGENT]];
+
+							*dst = 0;
+							*dst |= CLAMP(int(src[0] * multiplier), 0, 1023);
+							*dst |= CLAMP(int(src[1] * multiplier), 0, 1023) << 10;
+							*dst |= CLAMP(int(src[2] * multiplier), 0, 1023) << 20;
+							if (src[3] > 0) {
+								*dst |= 3 << 30;
+							}
+						}
+						src_offset += sizeof(uint32_t);
+					} else {
+						for (uint32_t i = 0; i < p_elements; i++) {
+							const float *src = (const float *)&src_vertex_ptr[i * src_vertex_stride + src_offset];
+							uint32_t *dst = (uint32_t *)&dst_vertex_ptr[i * dst_vertex_stride + dst_offsets[Mesh::ARRAY_TANGENT]];
+
+							*dst = 0;
+							*dst |= CLAMP(int(src[0] * 1023.0), 0, 1023);
+							*dst |= CLAMP(int(src[1] * 1023.0), 0, 1023) << 10;
+							*dst |= CLAMP(int(src[2] * 1023.0), 0, 1023) << 20;
+							if (src[3] > 0) {
+								*dst |= 3 << 30;
+							}
 						}
+						src_offset += sizeof(float) * 4;
 					}
-					src_offset += sizeof(float) * 4;
 				}
-
 			} break;
 			case OLD_ARRAY_COLOR: {
 				if (p_old_format & OLD_ARRAY_COMPRESS_COLOR) {