From ce4f58a06a07d9f4f3826449de5a5a791eb85f44 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 16 Aug 2025 14:35:23 +0300
Subject: [PATCH 01/15] Define the ConicalFrustum type

---
 src/GeometryBasics.jl            |  3 +-
 src/primitives/ConicalFrustum.jl | 54 ++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 src/primitives/ConicalFrustum.jl

diff --git a/src/GeometryBasics.jl b/src/GeometryBasics.jl
index d01865ae..b00e23ff 100644
--- a/src/GeometryBasics.jl
+++ b/src/GeometryBasics.jl
@@ -17,6 +17,7 @@ include("primitives/cylinders.jl")
 include("primitives/pyramids.jl")
 include("primitives/particles.jl")
 include("primitives/Cone.jl")
+include("primitives/ConicalFrustum.jl")
 
 include("interfaces.jl")
 include("viewtypes.jl")
@@ -68,7 +69,7 @@ if Base.VERSION >= v"1.8"
     include("precompiles.jl")
 end
 
-# Needed for GeometryBasicsGeoInterfaceExt. 
+# Needed for GeometryBasicsGeoInterfaceExt.
 # In future this can go away as can use Module dispatch.
 function geointerface_geomtype end
 
diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
new file mode 100644
index 00000000..31705074
--- /dev/null
+++ b/src/primitives/ConicalFrustum.jl
@@ -0,0 +1,54 @@
+"""
+A type that represents a conical frustum: a cone whose top has been cut off such,
+that the intersection of the cutting plane and the cone is a circle.
+"""
+struct ConicalFrustum{T} <: GeometryPrimitive{3,T}
+
+    """
+    The center point of the circular base.
+    """
+    baseCenter :: Point3{T}
+    """
+    The radius of the bottom circle.
+    """
+    baseRadius :: T
+
+    """
+    The center of the top circle.
+    """
+    topCenter :: Point3{T}
+
+    """
+    The radius of the top circle.
+    """
+    topRadius :: T
+
+    """
+    An inner constructor that validates the input values.
+    """
+    function ConicalFrustum(baseCenter,baseRadius,topCenter,topRadius)
+
+        baseRadius > 0 ? nothing : throw(ArgumentError("The base radius of a conical frustum needs to be positive."))
+
+        isfinite(baseRadius) ? nothing : throw(ArgumentError("The base radius of a conical frustum needs to be finite."))
+
+        topRadius > 0 ? nothing : throw(ArgumentError("The top radius of a conical frustum needs to be positive."))
+
+        isfinite(topRadius) ? nothing : throw(ArgumentError("The top radius of a conical frustum needs to be finite."))
+
+        new(baseCenter,baseRadius,topCenter,topRadius)
+
+    end # function
+
+end # struct
+
+"""
+An external constructor for converting inputs of different eltypes to a common type.
+"""
+function ConicalFrustum(baseCenter::Point3{T1},baseRadius::T2,topCenter::Point3{T3},topRadius::T4) where {T1,T2,T3,T4}
+
+    T = promote_type(T1,T2,T3,T4)
+
+    ConicalFrustum{T}(baseCenter,baseRadius,topCenter,topRadius)
+
+end # function

From 402473ba2d656d2f88f63337d61714b441dda549 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 16 Aug 2025 14:39:38 +0300
Subject: [PATCH 02/15] ConicalFrustum: add missing type parameter to inner
 constructor

---
 src/primitives/ConicalFrustum.jl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index 31705074..c6ec2772 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -26,7 +26,7 @@ struct ConicalFrustum{T} <: GeometryPrimitive{3,T}
     """
     An inner constructor that validates the input values.
     """
-    function ConicalFrustum(baseCenter,baseRadius,topCenter,topRadius)
+    function ConicalFrustum{T}(baseCenter,baseRadius,topCenter,topRadius) where T
 
         baseRadius > 0 ? nothing : throw(ArgumentError("The base radius of a conical frustum needs to be positive."))
 
@@ -36,7 +36,7 @@ struct ConicalFrustum{T} <: GeometryPrimitive{3,T}
 
         isfinite(topRadius) ? nothing : throw(ArgumentError("The top radius of a conical frustum needs to be finite."))
 
-        new(baseCenter,baseRadius,topCenter,topRadius)
+        new{T}(baseCenter,baseRadius,topCenter,topRadius)
 
     end # function
 

From 867640a64e2bc9af497077c4c052c1ca44211142 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 16 Aug 2025 14:54:22 +0300
Subject: [PATCH 03/15] Add external convenience constructors for creating
 ConicalFrustums from arrays and tuples

---
 src/primitives/ConicalFrustum.jl | 41 ++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index c6ec2772..f445928f 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -52,3 +52,44 @@ function ConicalFrustum(baseCenter::Point3{T1},baseRadius::T2,topCenter::Point3{
     ConicalFrustum{T}(baseCenter,baseRadius,topCenter,topRadius)
 
 end # function
+
+"""
+An external convenience constructor for creating instances from arrays instead of having to exlicitly create points.
+"""
+function ConicalFrustum(baseCenter::AbstractArray{T1},baseRadius::T2,topCenter::AbstractArray{T3},topRadius::T4) where {T1,T2,T3,T4}
+
+    baseCenterPoint = Point3{T1}(baseCenter)
+
+    topCenterPoint = Point3{T3}(topCenter)
+
+    ConicalFrustum(baseCenterPoint,baseRadius,topCenterPoint,topRadius)
+
+end # function
+
+"""
+An external convenience constructor for creating instances from NTuples instead of having to exlicitly create points.
+"""
+function ConicalFrustum(baseCenter::NTuple{3,T1},baseRadius::T2,topCenter::NTuple{3,T3},topRadius::T4) where {T1,T2,T3,T4}
+
+    baseCenterPoint = Point3{T1}(baseCenter)
+
+    topCenterPoint = Point3{T3}(topCenter)
+
+    ConicalFrustum(baseCenterPoint,baseRadius,topCenterPoint,topRadius)
+
+end # function
+
+"""
+An external convenience constructor for creating instances from Tuples instead of having to exlicitly create points.
+"""
+function ConicalFrustum(baseCenter::Tuple{T1,T2,T3},baseRadius::T4,topCenter::Tuple{T4,T5,T6},topRadius::T7) where {T1,T2,T3,T4,T5,T6,T7}
+
+    T = promote_type(T1,T2,T3,T4,T5,T6,T7)
+
+    baseCenterPoint = Point3{T}(baseCenter)
+
+    topCenterPoint = Point3{T}(topCenter)
+
+    ConicalFrustum(baseCenterPoint,baseRadius,topCenterPoint,topRadius)
+
+end # function

From a60265263b27ac294ba25beb84599b483c8c2b9f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 16 Aug 2025 15:03:12 +0300
Subject: [PATCH 04/15] ConicalFrustum: add validations for bottom and top
 centers in inner constructor

---
 src/primitives/ConicalFrustum.jl | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index f445928f..02b5e069 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -28,6 +28,10 @@ struct ConicalFrustum{T} <: GeometryPrimitive{3,T}
     """
     function ConicalFrustum{T}(baseCenter,baseRadius,topCenter,topRadius) where T
 
+        all(isfinite.(baseCenter)) ? nothing : throw(ArgumentError("The bottom circle center point of a conical frustum needs to have finite coordinates and be a number."))
+
+        all(isfinite.(topCenter)) ? nothing : throw(ArgumentError("The top circle center point of a conical frustum needs to have finite coordinates and be a number."))
+
         baseRadius > 0 ? nothing : throw(ArgumentError("The base radius of a conical frustum needs to be positive."))
 
         isfinite(baseRadius) ? nothing : throw(ArgumentError("The base radius of a conical frustum needs to be finite."))

From ea8a51f40bb6ceb0a0dc671c65ab553917b62cc8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 16 Aug 2025 15:30:22 +0300
Subject: [PATCH 05/15] ConicalFrustum: add functions for accessing fields and
 computing length, areas and volume

---
 src/primitives/ConicalFrustum.jl | 79 ++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index 02b5e069..5813ab76 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -97,3 +97,82 @@ function ConicalFrustum(baseCenter::Tuple{T1,T2,T3},baseRadius::T4,topCenter::Tu
     ConicalFrustum(baseCenterPoint,baseRadius,topCenterPoint,topRadius)
 
 end # function
+
+# Accessor functions for frustum fields.
+
+"""
+An accessor function for a base center.
+"""
+baseCenter(x::ConicalFrustum) = x.baseCenter
+
+"""
+An accessor function for base radius.
+"""
+baseRadius(x::ConicalFrustum) = x.baseRadius
+
+"""
+An accessor function for top center.
+"""
+topCenter(x::ConicalFrustum) = x.topCenter
+
+"""
+An accessor function for top radius.
+"""
+topRadius(x::ConicalFrustum) = x.topRadius
+
+# Functions for computing derived properties based on type field values.
+
+"""
+Computes the length of a frustum as the norm of the difference of its top and base centers.
+"""
+Base.length(x::ConicalFrustum) = LinearAlgebra.norm(topCenter(x) - baseCenter(x))
+
+"""
+Computes the area of the base of a given conical frustum.
+"""
+baseArea(x::ConicalFrustum) = pi * baseRadius(x) ^ 2
+
+"""
+Computes the area of the top of a given conical frustum.
+"""
+topArea(x::ConicalFrustum) = pi * topRadius(x) ^ 2
+
+"""
+Computes the slant length of a conical frustum.
+"""
+slantLength(x::ConicalFrustum) = sqrt( ( baseArea(x) - topArea(x) ) ^ 2 + length(x) ^ 2 )
+
+"""
+Computes the surface area of a frustum not including the top and bottom areas.
+"""
+function slantArea(x::ConicalFrustum)
+
+    baseRadiusVal = baseRadius(x)
+
+    topRadiusVal = topRadius(x)
+
+    lengthVal = length(x)
+
+    pi * (baseRadiusVal + topRadiusVal) * slantLength(x)
+
+end # function
+
+"""
+Computes the total surface area of a conical frustum.
+"""
+surfaceArea(x::ConicalFrustum) = baseArea(x) + topArea(x) + slantArea(x)
+
+"""
+Computes the volume of a conical frustum.
+"""
+function volume(x::ConicalFrustum)
+
+    baseRadiusVal = baseRadius(x)
+
+    topRadiusVal = topRadius(x)
+
+    lengthVal = length(x)
+
+    pi * lengthVal * ( baseRadiusVal ^ 2 + baseRadiusVal * topRadiusVal + topRadiusVal ^ 2 )/ 3
+
+end # function

From 865824322afaf70882c35b664ecda48caa6798f3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 16 Aug 2025 15:32:22 +0300
Subject: [PATCH 06/15] ConicalFrustum: add a missing space between binary
 operator and operand

---
 src/primitives/ConicalFrustum.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index 5813ab76..978dd3ec 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -173,6 +173,6 @@ function volume(x::ConicalFrustum)
 
     lengthVal = length(x)
 
-    pi * lengthVal * ( baseRadiusVal ^ 2 + baseRadiusVal * topRadiusVal + topRadiusVal ^ 2 )/ 3
+    pi * lengthVal * ( baseRadiusVal ^ 2 + baseRadiusVal * topRadiusVal + topRadiusVal ^ 2 ) / 3
 
 end # function

From 45eef9100fd4e112c67111d66d9ca86ec3eeb995 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 16 Aug 2025 15:36:02 +0300
Subject: [PATCH 07/15] ConicalFrustum: define centroid function

---
 src/primitives/ConicalFrustum.jl | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index 978dd3ec..9a9da0db 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -176,3 +176,8 @@ function volume(x::ConicalFrustum)
     pi * lengthVal * ( baseRadiusVal ^ 2 + baseRadiusVal * topRadiusVal + topRadiusVal ^ 2 ) / 3
 
 end # function
+
+"""
+Computes the centroid of a frustum: the mean between the base and top centers.
+"""
+centroid(x::ConicalFrustum) = (baseCenter(x) + topCenter(x)) / 2

From 752f30d4bad047d484d01390cd77b7ed48e2f558 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 16 Aug 2025 15:41:00 +0300
Subject: [PATCH 08/15] ConicalFrustum: change calls of {base,top}Area to
 {base,top}Radius in slantHeight

This was a typo.
---
 src/primitives/ConicalFrustum.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index 9a9da0db..b762270e 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -140,7 +140,7 @@ topArea(x::ConicalFrustum) = pi * topRadius(x) ^ 2
 """
 Computes the slant length of a conical frustum.
 """
-slantLength(x::ConicalFrustum) = sqrt( ( baseArea(x) - topArea(x) ) ^ 2 + length(x) ^ 2 )
+slantLength(x::ConicalFrustum) = sqrt( ( baseRadius(x) - topRadius(x) ) ^ 2 + length(x) ^ 2 )
 
 """
 Computes the surface area of a frustum not including the top and bottom areas.

From 8a32b7cb76c6611f95c8b514a7bd7378fb1e9329 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@tuni.fi>
Date: Mon, 18 Aug 2025 09:18:39 +0300
Subject: [PATCH 09/15] ConicalFrustum: add a line break to type definition for
 consistency

---
 src/primitives/ConicalFrustum.jl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index b762270e..fe6b5d9f 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -8,6 +8,7 @@ struct ConicalFrustum{T} <: GeometryPrimitive{3,T}
     The center point of the circular base.
     """
     baseCenter :: Point3{T}
+
     """
     The radius of the bottom circle.
     """

From 6a9e94dc19d4f4dc15ea2256164dcba4de84d8ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 23 Aug 2025 12:33:12 +0300
Subject: [PATCH 10/15] Define function coordinates(::ConicalFrustum, ...)

---
 src/primitives/ConicalFrustum.jl | 53 ++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index fe6b5d9f..249f314e 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -182,3 +182,56 @@ end # function
 Computes the centroid of a frustum: the mean between the base and top centers.
 """
 centroid(x::ConicalFrustum) = (baseCenter(x) + topCenter(x)) / 2
+
+"""
+Computes the coordinates required for the discretization
+of a frustum. The logic is the same as that for a cylinder,
+where the top and bottom circles are approximated using
+a polygon.
+"""
+function coordinates(c::ConicalFrustum{T}, nvertices=30) where {T}
+
+    nvertices += isodd(nvertices)
+
+    nhalf = div(nvertices, 2)
+
+    R = rotation(c)
+
+    step = 2pi / nhalf
+
+    ps = Vector{Point3{T}}(undef, nvertices + 2)
+
+    baseRadiusVal = baseRadius(c)
+
+    baseCenterVal = baseCenter(c)
+
+    topRadiusVal = topRadius(c)
+
+    topCenterVal = topCenter(c)
+
+    # First discretize the base...
+
+    for i in 1:nhalf
+
+        phi = (i-1) * step
+
+        ps[i] = R * Point3{T}(baseRadius * cos(phi), baseRadius * sin(phi), 0) + baseCenterVal
+
+    end
+
+    # ... and then the top circle.
+
+    for i in 1:nhalf
+
+        phi = (i-1) * step
+
+        ps[i + nhalf] = R * Point3{T}(topRadiusVal * cos(phi), topRadiusVal * sin(phi), 0) + topCenterVal
+    end
+
+    ps[end-1] = baseCenterVal
+
+    ps[end] = topCenterVal
+
+    return ps
+
+end # function

From 3671893e0e55e2a95b1a96714d7e56f318cc3846 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 23 Aug 2025 13:08:12 +0300
Subject: [PATCH 11/15] Define method direction(x::ConicalFrustum)

---
 src/primitives/ConicalFrustum.jl | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index 249f314e..abdf1e88 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -123,10 +123,15 @@ topRadius(x::ConicalFrustum) = x.topRadius
 
 # Functions for computing derived properties based on type field values.
 
+"""
+Computes the direction of a frustum, the difference between its top and base centers.
+"""
+direction(x::ConicalFrustum) = topCenter(x) - baseCenter(x)
+
 """
 Computes the length of a frustum as the norm of the difference of its top and base centers.
 """
-Base.length(x::ConicalFrustum) = LinearAlgebra.norm(topCenter(x) - baseCenter(x))
+Base.length(x::ConicalFrustum) = LinearAlgebra.norm(direction(x))
 
 """
 Computes the area of the base of a given conical frustum.

From 370d7eeda8fe8889234130349b9a3e3c3075ba4c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 23 Aug 2025 13:15:10 +0300
Subject: [PATCH 12/15] ConicalFrustum: fix variable name in coordinates method

---
 src/primitives/ConicalFrustum.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index abdf1e88..abeed946 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -220,7 +220,7 @@ function coordinates(c::ConicalFrustum{T}, nvertices=30) where {T}
 
         phi = (i-1) * step
 
-        ps[i] = R * Point3{T}(baseRadius * cos(phi), baseRadius * sin(phi), 0) + baseCenterVal
+        ps[i] = R * Point3{T}(baseRadiusVal * cos(phi), baseRadiusVal * sin(phi), 0) + baseCenterVal
 
     end
 

From ac0c4e4eab2e64bfcef5892839e73f72f58da5ec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 23 Aug 2025 13:21:15 +0300
Subject: [PATCH 13/15] Define method faces(::ConicalFrustum, ...)

---
 src/primitives/ConicalFrustum.jl | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index abeed946..a30c0233 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -240,3 +240,22 @@ function coordinates(c::ConicalFrustum{T}, nvertices=30) where {T}
     return ps
 
 end # function
+
+"""
+Computes the facial indices of a conical frustum,
+that can be used to index into the coordinates produced by the coordinates function.
+Again, follows the same logic as cylinders.
+"""
+function faces(::ConicalFrustum, facets=30)
+    nvertices = facets + isodd(facets)
+    nhalf = div(nvertices, 2)
+
+    disk1 = map(i -> GLTriangleFace(nvertices+1, mod1(i+1, nhalf), i), 1:nhalf)
+    mantle = map(1:nhalf) do i
+        i1 = mod1(i+1, nhalf)
+        QuadFace(i, i1, i1 + nhalf, i+nhalf)
+    end
+    disk2 = map(i -> GLTriangleFace(nvertices+2, i+nhalf, mod1(i+1, nhalf)+nhalf), 1:nhalf)
+
+    return vcat(disk1, mantle, disk2)
+end

From a67d57a0340e65e9aa188bb1e78c559ba9b72eaa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 23 Aug 2025 13:27:53 +0300
Subject: [PATCH 14/15] Add method normals(c::ConicalFrustum, ...)

---
 src/primitives/ConicalFrustum.jl | 40 ++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index a30c0233..c8d69a5b 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -241,6 +241,46 @@ function coordinates(c::ConicalFrustum{T}, nvertices=30) where {T}
 
 end # function
 
+"""
+Computes the surface normals of the discrtization of a conical frustum.
+Follows the same logic as cylinders.
+"""
+function normals(c::ConicalFrustum, nvertices = 30)
+
+    nvertices += isodd(nvertices)
+
+    nhalf = div(nvertices, 2)
+
+    R = rotation(c)
+
+    step = 2pi / nhalf
+
+    ns = Vector{Vec3f}(undef, nhalf + 2)
+
+    for i in 1:nhalf
+
+        phi = (i-1) * step
+
+        ns[i] = R * Vec3f(cos(phi), sin(phi), 0)
+
+    end
+
+    ns[end-1] = R * Vec3f(0, 0, -1)
+
+    ns[end] = R * Vec3f(0, 0, 1)
+
+    disk1 = map(i -> GLTriangleFace(nhalf+1), 1:nhalf)
+
+    mantle = map(i -> QuadFace(i, mod1(i+1, nhalf), mod1(i+1, nhalf), i), 1:nhalf)
+
+    disk2 = map(i -> GLTriangleFace(nhalf+2), 1:nhalf)
+
+    fs = vcat(disk1, mantle, disk2)
+
+    return FaceView(ns, fs)
+
+end
+
 """
 Computes the facial indices of a conical frustum,
 that can be used to index into the coordinates produced by the coordinates function.

From 235b3c1cd7656f5b93f619faa14757fe71bfaf8a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Santtu=20S=C3=B6derholm?= <santtu.soderholm@protonmail.com>
Date: Sat, 23 Aug 2025 13:29:36 +0300
Subject: [PATCH 15/15] ConicalFrustum: rename "slant" to "mantle"

---
 src/primitives/ConicalFrustum.jl | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/primitives/ConicalFrustum.jl b/src/primitives/ConicalFrustum.jl
index c8d69a5b..53719f6d 100644
--- a/src/primitives/ConicalFrustum.jl
+++ b/src/primitives/ConicalFrustum.jl
@@ -144,14 +144,14 @@ Computes the area of the top of a given conical frustum.
 topArea(x::ConicalFrustum) = pi * topRadius(x) ^ 2
 
 """
-Computes the slant length of a conical frustum.
+Computes the mantle length of a conical frustum.
 """
-slantLength(x::ConicalFrustum) = sqrt( ( baseRadius(x) - topRadius(x) ) ^ 2 + length(x) ^ 2 )
+mantleLength(x::ConicalFrustum) = sqrt( ( baseRadius(x) - topRadius(x) ) ^ 2 + length(x) ^ 2 )
 
 """
 Computes the surface area of a frustum not including the top and bottom areas.
 """
-function slantArea(x::ConicalFrustum)
+function mantleArea(x::ConicalFrustum)
 
     baseRadiusVal = baseRadius(x)
 
@@ -159,14 +159,14 @@ function slantArea(x::ConicalFrustum)
 
     lengthVal = length(x)
 
-    pi * (baseRadiusVal + topRadiusVal) * slantLength(x)
+    pi * (baseRadiusVal + topRadiusVal) * mantleLength(x)
 
 end # function
 
 """
 Computes the total surface area of a conical frustum.
 """
-surfaceArea(x::ConicalFrustum) = baseArea(x) + topArea(x) + slantArea(x)
+surfaceArea(x::ConicalFrustum) = baseArea(x) + topArea(x) + mantleArea(x)
 
 """
 Computes the volume of a conical frustum.