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Create tangent array if mesh created without tangents
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This extends our previous change to ensure that compressed meshes have tangents

Now we ensure tangents are always used. This greatly simplifies our compression code at the cost of a small amount of bandwidth
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@clayjohn
clayjohn committed Nov 7, 2023
1 parent 4c96e96 commit 031f221
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Showing 2 changed files with 42 additions and 10 deletions.
13 changes: 10 additions & 3 deletions scene/resources/immediate_mesh.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -166,7 +166,7 @@ void ImmediateMesh::surface_end() {
normal_tangent_stride += sizeof(uint32_t);
}
uint32_t tangent_offset = 0;
if (uses_tangents) {
if (uses_tangents || uses_normals) {
format |= ARRAY_FORMAT_TANGENT;
tangent_offset = vertex_stride * vertices.size() + normal_tangent_stride;
normal_tangent_stride += sizeof(uint32_t);
Expand Down Expand Up @@ -202,9 +202,16 @@ void ImmediateMesh::surface_end() {

*normal = value;
}
if (uses_tangents) {
if (uses_tangents || uses_normals) {
uint32_t *tangent = (uint32_t *)&surface_vertex_ptr[i * normal_tangent_stride + tangent_offset];
Vector2 t = tangents[i].normal.octahedron_tangent_encode(tangents[i].d);
Vector2 t;
if (uses_tangents) {
t = tangents[i].normal.octahedron_tangent_encode(tangents[i].d);
} else {
Vector3 tan = Vector3(0.0, 1.0, 0.0).cross(normals[i].normalized());
t = tan.octahedron_tangent_encode(1.0);
}

uint32_t value = 0;
value |= (uint16_t)CLAMP(t.x * 65535, 0, 65535);
value |= (uint16_t)CLAMP(t.y * 65535, 0, 65535) << 16;
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39 changes: 32 additions & 7 deletions servers/rendering_server.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -635,7 +635,8 @@ Error RenderingServer::_surface_set_data(Array p_arrays, uint64_t p_format, uint
// If using compression we store tangent while storing vertices.
if (!(p_format & RS::ARRAY_FLAG_COMPRESS_ATTRIBUTES)) {
Variant::Type type = p_arrays[ai].get_type();
ERR_FAIL_COND_V(type != Variant::PACKED_FLOAT32_ARRAY && type != Variant::PACKED_FLOAT64_ARRAY, ERR_INVALID_PARAMETER);
ERR_FAIL_COND_V(type != Variant::PACKED_FLOAT32_ARRAY && type != Variant::PACKED_FLOAT64_ARRAY && type != Variant::NIL, ERR_INVALID_PARAMETER);

if (type == Variant::PACKED_FLOAT32_ARRAY) {
Vector<float> array = p_arrays[ai];
ERR_FAIL_COND_V(array.size() != p_vertex_array_len * 4, ERR_INVALID_PARAMETER);
Expand All @@ -657,7 +658,7 @@ Error RenderingServer::_surface_set_data(Array p_arrays, uint64_t p_format, uint

memcpy(&vw[p_offsets[ai] + i * p_normal_stride], vector, 4);
}
} else { // PACKED_FLOAT64_ARRAY
} else if (type == Variant::PACKED_FLOAT64_ARRAY) {
Vector<double> array = p_arrays[ai];
ERR_FAIL_COND_V(array.size() != p_vertex_array_len * 4, ERR_INVALID_PARAMETER);
const double *src_ptr = array.ptr();
Expand All @@ -676,6 +677,30 @@ Error RenderingServer::_surface_set_data(Array p_arrays, uint64_t p_format, uint
vector[0] = 65535;
}

memcpy(&vw[p_offsets[ai] + i * p_normal_stride], vector, 4);
}
} else { // No tangent array.
ERR_FAIL_COND_V(p_arrays[RS::ARRAY_NORMAL].get_type() != Variant::PACKED_VECTOR3_ARRAY, ERR_INVALID_PARAMETER);

Vector<Vector3> normal_array = p_arrays[RS::ARRAY_NORMAL];
ERR_FAIL_COND_V(normal_array.size() != p_vertex_array_len, ERR_INVALID_PARAMETER);
const Vector3 *normal_src = normal_array.ptr();
// Set data for tangent.
for (int i = 0; i < p_vertex_array_len; i++) {
// Generate an arbitrary vector that is tangential to normal.
Vector3 tan = Vector3(0.0, 1.0, 0.0).cross(normal_src[i].normalized());
Vector2 res = tan.octahedron_tangent_encode(1.0);
uint16_t vector[2] = {
(uint16_t)CLAMP(res.x * 65535, 0, 65535),
(uint16_t)CLAMP(res.y * 65535, 0, 65535),
};

if (vector[0] == 0 && vector[1] == 65535) {
// (1, 1) and (0, 1) decode to the same value, but (0, 1) messes with our compression detection.
// So we sanitize here.
vector[0] = 65535;
}

memcpy(&vw[p_offsets[ai] + i * p_normal_stride], vector, 4);
}
}
Expand Down Expand Up @@ -1172,6 +1197,11 @@ Error RenderingServer::mesh_create_surface_data_from_arrays(SurfaceData *r_surfa
} break;
}
ERR_FAIL_COND_V(array_len == 0, ERR_INVALID_DATA);
} else if (i == RS::ARRAY_NORMAL) {
if (p_arrays[RS::ARRAY_TANGENT].get_type() == Variant::NIL) {
// We must use tangents if using normals.
format |= (1ULL << RS::ARRAY_TANGENT);
}
} else if (i == RS::ARRAY_BONES) {
switch (p_arrays[i].get_type()) {
case Variant::PACKED_INT32_ARRAY: {
Expand Down Expand Up @@ -1242,11 +1272,6 @@ Error RenderingServer::mesh_create_surface_data_from_arrays(SurfaceData *r_surfa
ERR_FAIL_COND_V_MSG(!(format & RS::ARRAY_FORMAT_NORMAL), ERR_INVALID_PARAMETER, "Can't use compression flag 'ARRAY_FLAG_COMPRESS_ATTRIBUTES' while using tangents without normal array.");
}

if ((format & RS::ARRAY_FLAG_COMPRESS_ATTRIBUTES) && !(format & RS::ARRAY_FORMAT_TANGENT)) {
// If no tangent array provided, we will generate one.
format |= RS::ARRAY_FORMAT_TANGENT;
}

int vertex_array_size = (vertex_element_size + normal_element_size) * array_len;
int attrib_array_size = attrib_element_size * array_len;
int skin_array_size = skin_element_size * array_len;
Expand Down

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