Classic Elite ships wireframe - Revision history

DrBeeb at 04:56, 10 June 2018

2018-06-10T04:56:38Z

DrBeeb at 04:51, 10 June 2018

2018-06-10T04:51:55Z

DrBeeb at 04:26, 10 June 2018

2018-06-10T04:26:52Z

DrBeeb at 04:20, 10 June 2018

2018-06-10T04:20:27Z

DrBeeb at 04:11, 10 June 2018

2018-06-10T04:11:19Z

DrBeeb at 04:00, 10 June 2018

2018-06-10T04:00:19Z

DrBeeb at 03:51, 10 June 2018

2018-06-10T03:51:31Z

DrBeeb at 03:39, 10 June 2018

2018-06-10T03:39:39Z

DrBeeb: Created page with "In Classic Elite the ship geometries are limited to convex hulls to aid in rendering the wire-frame graphics as quickly as possible with hidden line removal. Each vertex is us..."

2018-06-10T03:13:27Z

Created page with "In Classic Elite the ship geometries are limited to convex hulls to aid in rendering the wire-frame graphics as quickly as possible with hidden line removal. Each vertex is us..."

New page

In Classic Elite the ship geometries are limited to convex hulls to aid in rendering the wire-frame graphics as quickly as possible with hidden line removal. Each vertex is usually associated with 4 faces, each edge joining 2 vertices is associated with 2 faces. The maximum number of faces is 14, as is the case for the asteroid model. Face 15 is reserved to indicate a vertex is always visible regardless of the objection's orientation, e.g. more than 4 faces meet at that vertex. The (time consuming) 3D projection calculations for that vertex should always be performed, if the vertex is close enough to the player, else if the face is not visible then further tests are done to see if any visible face is associated with that vertex. An edge is only rendered if both faces associated with it are visible.

== Ship data file format ==

An initial header of 20 bytes is followed by the vertex data, in groups of 6 bytes, then the edge data in groups of 4 bytes, and finally the face normal data in groups of 4 bytes.

{| class="wikitable"
! style="text-align:left;"| Byte (in Hex)
! Ship header information (example ship)
|-

|03
|hi nibble is cargo type if scooped (0 is not scoopable). lo nibble is max pieces of debris if destroyed.
|-

|E9
|lo byte of ship area for target hit decision
|-

|07
|hi byte of ship area for target hit decision
|-

|86
|lo byte of offset to edge data.
|-

|F2
|lo byte of offset to face data.
|-

|5D
|maximum size of heap reserved for processed line plotting data (1+4*max visible edges)
|-

|00
|vertex id for laser gun (*4), used for firing laser lines
|-

|1A
|number of vertices(*4 + 6), used for explosion dust origin(s)
|-

|72
|number of vertices*6, used for vertex loop counter
|-

|1B
|number of edges
|-

|2C
|lo byte of bounty (in units of 0.1 Cr) if awarded
|-

|01
|hi byte of bounty (in units of 0.1 Cr) if awarded
|-

|28
|number of faces*4, used for face loop counter
|-

|1E
|distance away when wireframe rendering replaced by large dot
|-

|A0
|Maximum ship energy
|-

|1E
|Maximum ship speed
|-

|00
|hi byte of offset to edge data.
|-

|00
|hi byte of offset to face data.
|-

|01
|Scale factor for ship size when calculating whether face normal is visible
|-

|22
|Laser firepower*8 plus maximum number (7) of missiles.
|}

Each vertex has 6 bytes of data.
{| class="wikitable"
! style="text-align:left;"| Byte X
! Byte Y | ! Byte Z | Byte S | Byte F1 | Byte F2
|-

|00
|0E
|6C
|5F
|01
|59
|-

|...
||||||
|}

Source code for the BBC tape and TUBE versions of BBC Elite can be found at [http://www.iancgbell.clara.net/elite/text/index.htm Ian Bell's] web site and were used to disassemble and interpret the Disk version described here.

[[Category:Classic]]

@@ Line 128: / Line 128: @@
 Each edge has 4 bytes of data. The visibility distance is stored in Byte V, with a maximum value of 31.
-The 2 faces associated with each edge are stored in the 2 nibbles of Bytes F.
+The 2 faces associated with each edge are stored in the 2 nibbles of Byte F.
-Byte N1 contains the vertex id (*4) for one end of the edge, Byte N2 the other end.
+Byte N1 contains the vertex id (*4) for one end of the line, Byte N2 the other end.
 {| class="wikitable"

@@ Line 1: / Line 1: @@
 In Classic Elite the ship geometries are limited to convex hulls to aid in rendering the wire-frame graphics as quickly as possible with hidden line removal. Each vertex is usually associated with 4 faces, each edge joining 2 vertices is associated with 2 faces.
-The maximum number of faces is 14, as is the case for the asteroid model. Face 15 is reserved to indicate a vertex is always visible regardless of the objection's orientation, or more than 4 faces meet at that vertex. Otherwise at least 1 face associated with that vertex must be visible (its normal has a component pointing at the player) for that vertex to be considered further.
+The maximum number of faces is 14+1, as is the case for the asteroid model. Counting from zero, Face 15 is reserved to indicate a vertex is always visible regardless of the objection's orientation, or more than 4 faces meet at that vertex. Otherwise at least 1 face associated with that vertex must be visible (its normal has a component pointing at the player) for that vertex to be considered further.
 The (time consuming) 3D projection calculations for a visible vertex (associated with a visible face) are performed if the vertex is close enough to the player.

@@ Line 5: / Line 5: @@
 The (time consuming) 3D projection calculations for a visible vertex (associated with a visible face) are performed if the vertex is close enough to the player.
-An edge is only rendered if either of the two faces associated with it are visible, and the edge is close enough to be visible.
+A line joining two vertices is only rendered if either of the two faces associated with it are visible, and the edge is close enough to be visible. The ship's data file design most ensure that any required vertices are already visible and have been projected.
 == Ship data file format ==

← Older revision		Revision as of 04:20, 10 June 2018
Line 1:		Line 1:
−	In Classic Elite the ship geometries are limited to convex hulls to aid in rendering the wire-frame graphics as quickly as possible with hidden line removal. Each vertex is usually associated with 4 faces, each edge joining 2 vertices is associated with 2 faces~~. The maximum number of faces is 14, as is the case for the asteroid model~~.	+	In Classic Elite the ship geometries are limited to convex hulls to aid in rendering the wire-frame graphics as quickly as possible with hidden line removal. Each vertex is usually associated with 4 faces, each edge joining 2 vertices is associated with 2 faces.
−	Face 15 is reserved to indicate a vertex is always visible regardless of the objection's orientation, e.g. more than 4 faces meet at that vertex. The (time consuming) 3D projection calculations for that vertex should always be performed, if the vertex is close enough to the player.

−	If a face is not visible then further tests are done to see if any face associated with that (close enough) vertex is visible. An edge is only rendered if either of the two faces associated with it are visible, and the edge is close enough to be visible.
		+	The maximum number of faces is 14, as is the case for the asteroid model. Face 15 is reserved to indicate a vertex is always visible regardless of the objection's orientation, or more than 4 faces meet at that vertex. Otherwise at least 1 face associated with that vertex must be visible (its normal has a component pointing at the player) for that vertex to be considered further.
		+
		+	The (time consuming) 3D projection calculations for a visible vertex (associated with a visible face) are performed if the vertex is close enough to the player.
		+
		+	An edge is only rendered if either of the two faces associated with it are visible, and the edge is close enough to be visible.

	== Ship data file format ==		== Ship data file format ==

← Older revision		Revision as of 04:11, 10 June 2018
Line 1:		Line 1:
−	In Classic Elite the ship geometries are limited to convex hulls to aid in rendering the wire-frame graphics as quickly as possible with hidden line removal. Each vertex is usually associated with 4 faces, each edge joining 2 vertices is associated with 2 faces. The maximum number of faces is 14, as is the case for the asteroid model. Face 15 is reserved to indicate a vertex is always visible regardless of the objection's orientation, e.g. more than 4 faces meet at that vertex. The (time consuming) 3D projection calculations for that vertex should always be performed, if the vertex is close enough to the player, else if the face is not visible then further tests are done to see if any visible face is associated with that vertex. An edge is only rendered if both faces associated with it are visible.	+	In Classic Elite the ship geometries are limited to convex hulls to aid in rendering the wire-frame graphics as quickly as possible with hidden line removal. Each vertex is usually associated with 4 faces, each edge joining 2 vertices is associated with 2 faces. The maximum number of faces is 14, as is the case for the asteroid model.
		+	Face 15 is reserved to indicate a vertex is always visible regardless of the objection's orientation, e.g. more than 4 faces meet at that vertex. The (time consuming) 3D projection calculations for that vertex should always be performed, if the vertex is close enough to the player.
		+
		+	If a face is not visible then further tests are done to see if any face associated with that (close enough) vertex is visible. An edge is only rendered if either of the two faces associated with it are visible, and the edge is close enough to be visible.

	== Ship data file format ==		== Ship data file format ==

@@ Line 90: / Line 90: @@
 |}
-Each vertex has 6 bytes of data. Bytes X,Y,Z are the magnitudes. The signs for each axis are stored in bits 7,6,5 of Byte S. The lower 5 bits are a visibility distance, with a maximum value of 31 ensuring the vertex is processed for all distances until the ship is plotted as a large dot.
+Each vertex has 6 bytes of data. Bytes X,Y,Z are the magnitudes of the 3D coordinate. The signs for each component are stored in bits 7,6,5 of Byte S. The lower 5 bits are a visibility distance, with a maximum value of 31 ensuring the vertex is processed for all distances until the ship is plotted as a large dot.
 {| class="wikitable"
 ! style="text-align:left;"| Byte X
@@ Line 118: / Line 118: @@
 |...
 |||||||
 |}