Documentation Talk:Tutorial Section 3 - Revision history

Jholsenback: closed tags

2016-05-24T16:05:31Z

closed tags

Wfpokorny at 12:56, 24 May 2016

2016-05-24T12:56:37Z

Wfpokorny at 12:52, 24 May 2016

2016-05-24T12:52:23Z

Jholsenback: follow up

2016-05-23T11:22:56Z

follow up

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Wfpokorny: /* Lathe Object */ Suggested rewording

2016-05-22T16:06:48Z

Lathe Object: Suggested rewording

Jholsenback: heading chages

2010-03-25T07:19:51Z

heading chages

Chrisb: Created page with '

This document is protected, so submissions, corrections and discuss…'
2009-10-22T12:56:38Z

Created page with ' <table width=100% border=1 cellspacing=0 cellpadding=5> <tr><td width=100% bgcolor=#FFEEEE> This document is protected, so submissions, corrections and discuss…'
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@@ Line 33: / Line 33: @@
 before this gets too confusing, let's start one step at a time with the
 simplest form of prism. We enter and render the following POV code (see file
-<code>prismdm1.pov</code>).</p
+<code>prismdm1.pov</code>).</p>
 * that I think should read:
@@ Line 46: / Line 46: @@
 before this gets too confusing, let's start one step at a time with the
 simplest form of prism. We enter and render the following POV code (see file
-<code>prismdm1.pov</code>).</p
+<code>prismdm1.pov</code>).</p>

← Older revision		Revision as of 12:56, 24 May 2016
Line 19:		Line 19:
	the cubic and the bezier spline. Sure enough, we can use these with prisms to make a more		the cubic and the bezier spline. Sure enough, we can use these with prisms to make a more
	free form, smoothly curving type of prism.</p>		free form, smoothly curving type of prism.</p>
		+
		+
		+
		+	* And one more which now reads:
		+
		+	====Prism Object====
		+	<p>The prism is essentially a polygon or closed curve which is swept along a
		+	linear path. We can imagine the shape so swept leaving a trail in space, and
		+	the surface of that trail is the surface of our prism. The curve or polygon
		+	making up a prism's face can be a composite of any number of sub-shapes,
		+	can use any kind of three different splines, and can either keep a constant
		+	width as it is swept, or slowly tapering off to a fine point on one end. But
		+	before this gets too confusing, let's start one step at a time with the
		+	simplest form of prism. We enter and render the following POV code (see file
		+	<code>prismdm1.pov</code>).</p
		+
		+	* that I think should read:
		+
		+	====Prism Object====
		+	<p>The prism is essentially a polygon or closed curve which is swept along a
		+	linear path. We can imagine the shape so swept leaving a trail in space, and
		+	the surface of that trail is the surface of our prism. The curve or polygon
		+	making up a prism's face can be a composite of any number of sub-shapes,
		+	can use any kind of four different splines, and can either keep a constant
		+	width as it is swept, or slowly tapering off to a fine point on one end. But
		+	before this gets too confusing, let's start one step at a time with the
		+	simplest form of prism. We enter and render the following POV code (see file
		+	<code>prismdm1.pov</code>).</p

← Older revision		Revision as of 12:52, 24 May 2016
Line 1:		Line 1:
−	~~<p>~~
−	~~First, we would like to digress a moment to talk about the difference~~
−	~~between a lathe and a surface of revolution object (SOR). The SOR object,~~
−	~~described in a separate tutorial, may seem terribly similar to the lathe at~~
−	~~first glance. It too declares a series of points and connects them with~~
−	~~curving lines and then rotates them around the y-axis. The lathe has~~
−	~~advantages, such as linear, quadratic, cubic and bezier spline support. </p>~~
−	~~<p>~~
−	~~Plus, the simpler mathematics used by a SOR does not allow the curve to double~~
−	~~back over the same y-coordinates, thus, if using a SOR, any sudden twist~~
−	~~which cuts back down over the same heights that the curve previously covered~~
−	~~will trigger an error. For example, suppose we wanted a lathe to arc up from~~
−	~~<0,0> to <2,2>, then to dip back down to <4,0>. Rotated~~
−	~~around the y-axis, this would produce something like a gelatin mold - a~~
−	~~rounded semi torus, hollow in the middle. But with the SOR, as soon as the~~
−	~~curve doubled back on itself in the y-direction, it would become an illegal~~
−	~~declaration.</p>~~

−	* ~~picked up suggested changes~~ -- [[~~User~~:~~Jholsenback~~\|~~jholsenback~~]]	+	* Jim, Thanks for making the earlier update. I noticed another place in the prism part of the tutorial where we should mention the bezier spline.
		+
		+	* Where we today have:
		+
		+	=====Teaching An Old Spline New Tricks=====
		+	<p>If we followed the section on splines covered under the lathe tutorial
		+	(see the section <!--<linkto "Understanding The Concept of Splines">Understanding The Concept of Splines</linkto>--->[[Documentation:Tutorial Section 3#Understanding The Concept of Splines\|Understanding The Concept of Splines]]), we know that
		+	there are two additional kinds of splines besides linear: the quadratic and
		+	the cubic spline. Sure enough, we can use these with prisms to make a more
		+	free form, smoothly curving type of prism.</p>
		+
		+	* I think it should read:
		+
		+	=====Teaching An Old Spline New Tricks=====
		+	<p>If we followed the section on splines covered under the lathe tutorial
		+	(see the section <!--<linkto "Understanding The Concept of Splines">Understanding The Concept of Splines</linkto>--->[[Documentation:Tutorial Section 3#Understanding The Concept of Splines\|Understanding The Concept of Splines]]), we know that
		+	there are three additional kinds of splines besides linear: the quadratic,
		+	the cubic and the bezier spline. Sure enough, we can use these with prisms to make a more
		+	free form, smoothly curving type of prism.</p>

@@ Line 84: / Line 84: @@
 described in a separate tutorial, may seem terribly similar to the lathe at
 first glance. It too declares a series of points and connects them with
-curving lines and then rotates them around the y-axis. The lathe has certain
+curving lines and then rotates them around the y-axis. The lathe has
-advantages, such as different kinds of splines, linear, quadratic and cubic,
+advantages, such as linear, quadratic, cubic and bezier spline support. </p>
 <p>
-The simpler mathematics used by a SOR does not allow the curve to double
+Plus, the simpler mathematics used by a SOR does not allow the curve to double
 back over the same y-coordinates, thus, if using a SOR, any sudden twist
 which cuts back down over the same heights that the curve previously covered

@@ Line 7: / Line 7: @@
 <br>
 <!--</wikitalk>--->
-===Advanced Features===
+==Advanced Features==
 <!--<sectiondesc desc=<"advanced tutorial">--->
 ===Spline Based Shapes===
@@ Line 23: / Line 23: @@
 before proceeding with these advanced shapes.</p>
-===Lathe Object===
+====Lathe Object====
 <!--<indexentry "lathe, tutorial">--->
 <p>In the real world, <code><!--<linkto "lathe">lathe</linkto>--->[[Documentation:Reference Section 4#Lathe|lathe]]</code> refers to a process of making
@@ Line 102: / Line 102: @@
 in the end, it is a matter of: we use a SOR if its limitations will allow, but
 when we need a more flexible shape, we go with the lathe instead.</p>
-===Understanding The Concept of Splines===
+=====Understanding The Concept of Splines=====
 <!--<indexentry "Splines, understanding the concept of">--->
 <p>It would be helpful, in order to understand splines, if we had a sort of
@@ Line 370: / Line 370: @@
 quickly get a feel for working with them.</p>
-===Surface of Revolution Object===
+====Surface of Revolution Object====
 <!--<indexentry "sor, tutorial">--->
 <p>Bottles, vases and glasses make nice objects in ray-traced scenes. We want
@@ Line 434: / Line 434: @@
 any height.</p>
-===Prism Object===
+====Prism Object====
 <!--<indexentry "prism, tutorial">--->
 <p>The prism is essentially a polygon or closed curve which is swept along a
@@ Line 476: / Line 476: @@
 issued. However, this only works with linear splines, so we must not get
 too casual about those warning messages!</p>
-===Teaching An Old Spline New Tricks===
+=====Teaching An Old Spline New Tricks=====
 <!--<indexentry "Spline, new tricks" "cubic_spline, tutorial">--->
 <p>If we followed the section on splines covered under the lathe tutorial
@@ Line 534: / Line 534: @@
 are not part of the shape - they are just there to help compute what
 curves to use between the other points.</p>
-===Smooth Transitions===
+=====Smooth Transitions=====
 <p>Now a handy thing to note is that we have made point one equal point four,
 and also point six equals point three. Yes, this is important. Although this
@@ Line 549: / Line 549: @@
 equal to the second from last point.</p>
-===Multiple Sub-Shapes===
+=====Multiple Sub-Shapes=====
 <p>Just as with the polygon object (see section
 &quot;<!--<linkto "Polygon Object">Polygon Object</linkto>--->[[Documentation:Tutorial Section 3.1#Polygon Object|Polygon Object]]&quot;)
@@ Line 591: / Line 591: @@
 any number of extremely complex prism shapes!</p>
-===Conic Sweeps And The Tapering Effect===
+=====Conic Sweeps And The Tapering Effect=====
 <!--<indexentry "Tapering Conic Sweeps">--->
 <p>In our original prism, the keyword <code>linear_sweep</code> is actually
@@ Line 689: / Line 689: @@
 to its point, giving us a pyramid without a cap. Exactly how much of the cap
 is cut off depends on how close the first height is to the second height.</p>
-===Sphere Sweep Object===
+====Sphere Sweep Object====
 <!--<indexentry "sphere_sweep, tutorial">--->
 <p>A Sphere Sweep Object is the space a sphere occupies during its movement along a spline.
@@ Line 754: / Line 754: @@
 <p>When using a b_spline, the resulting object is somewhat similar to the cubic
 sweep, but does not actually go through the control points. It lies somewhere between them.</p>
-===Bicubic Patch Object===
+====Bicubic Patch Object====
 <!--<indexentry "bicubic_patch, tutorial">--->
 <p>
@@ Line 1,023: / Line 1,023: @@
 <p> [[Image:TutImgBpatch03.png|3 patches, some control points]] </p>
-===Text Object===
+====Text Object====
 <!--<indexentry "text, tutorial">--->
 <p>The <code>text</code> object is a primitive that can use TrueType fonts