Fur Shader Passes - Revision history

Warren: /* Pass 3 - The Overcoat */

2024-01-01T21:39:04Z

Pass 3 - The Overcoat

← Older revision		Revision as of 14:39, 1 January 2024
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	== Pass 3 - The Overcoat ==		== Pass 3 - The Overcoat ==
	Added in v5.0, the overcoat is a translucent layer of fur that acts as a cheap visual stand-in for actual fur when the avatar is far away. It allows the shader to turn the "real" fur layers off completely, which results in a ~~very large~~ speed boost.		Added in v5.0, the overcoat is a translucent layer of fur that acts as a cheap visual stand-in for actual fur when the avatar is far away. It allows the shader to turn the "real" fur layers off completely, which results in a significant speed boost.

	At close range the overcoat is not visible, but as distance increases the overcoat fades in and expands outwards to about 2/3rds the thickness of the fur.		At close range the overcoat is not visible, but as distance increases the overcoat fades in and expands outwards to about 2/3rds the thickness of the fur.

Warren: /* Pass 2 - The Fur */

2023-12-31T23:24:08Z

Pass 2 - The Fur

← Older revision		Revision as of 16:24, 31 December 2023
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	* Trick #1: it can turn the fur layers off (if too far away, offscreen, or backwards) by having the Hull shader ask the Tessellator to multiply the number of triangles by 0, which throws them out before they reach the Geometry shader stage. This is a MASSIVE speed boost, roughly doubling the speed of the shader.		* Trick #1: it can turn the fur layers off (if too far away, offscreen, or backwards) by having the Hull shader ask the Tessellator to multiply the number of triangles by 0, which throws them out before they reach the Geometry shader stage. This is a MASSIVE speed boost, roughly doubling the speed of the shader.

	* Trick #2: it can have the Hull shader ask the Tessellator split each triangle into 4 when taking a photo. However, the Domain shader then ignores the Tessellator, and instead just makes 4 copies of the original, un-tessellated triangle. The fur can thus be rendered at up to 4x resolution, but only when needed.		* Trick #2: it can have the Hull shader ask the Tessellator split each triangle into 4 when taking a photo. However, the Domain shader then ignores the Tessellator's instructions, and instead just makes 4 copies of the original, un-tessellated triangle. The fur can thus be rendered at up to 4x resolution, but only when needed.

	== Pass 3 - The Overcoat ==		== Pass 3 - The Overcoat ==

Warren at 23:20, 31 December 2023

2023-12-31T23:20:07Z

← Older revision		Revision as of 16:20, 31 December 2023
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	However, an unexpected benefit of rendering the skin separately is that it actually renders faster than doing everything in 1 pass. As far as I can tell (and this is really just a guess!), trying to render the opaque skin at the same time as the mostly see-through fur results in the GPU caches missing a lot.		However, an unexpected benefit of rendering the skin separately is that it actually renders faster than doing everything in 1 pass. As far as I can tell (and this is really just a guess!), trying to render the opaque skin at the same time as the mostly see-through fur results in the GPU caches missing a lot.

	The speed increase is so great, in fact, that 16 "cheap" fur layers + 1 "expensive" skin layer ~~render~~ significantly faster than 15 "cheap" fur layers + 1 "cheap" skin layer.		The speed increase is so great, in fact, that 16 "cheap" fur layers + 1 "expensive" skin layer renders significantly faster than 15 "cheap" fur layers + 1 "cheap" skin layer.

	== Pass 2 - The Fur ==		== Pass 2 - The Fur ==

Warren at 23:19, 31 December 2023

2023-12-31T23:19:42Z

← Older revision		Revision as of 16:19, 31 December 2023
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	Many lighting effects, such as proper specular lighting and normal maps, are simply too slow to calculate for every layer of fur. As a compromise, my shader only renders the skin "expensively".		Many lighting effects, such as proper specular lighting and normal maps, are simply too slow to calculate for every layer of fur. As a compromise, my shader only renders the skin "expensively".

	However, an unexpected benefit of rendering the skin separately is that it actually renders faster than doing everything in 1 pass. As far as I can tell (and is really just a guess!), trying to render the opaque skin at the same time as the mostly see-through fur results in the GPU caches missing a lot.		However, an unexpected benefit of rendering the skin separately is that it actually renders faster than doing everything in 1 pass. As far as I can tell (and this is really just a guess!), trying to render the opaque skin at the same time as the mostly see-through fur results in the GPU caches missing a lot.

	The speed increase is so great, in fact, that 16 "cheap" fur layers + 1 "expensive" skin layer render significantly faster than 15 "cheap" fur layers + 1 "cheap" skin layer.		The speed increase is so great, in fact, that 16 "cheap" fur layers + 1 "expensive" skin layer render significantly faster than 15 "cheap" fur layers + 1 "cheap" skin layer.

Warren: Warren moved page Fur Shader Layers to Fur Shader Passes

2023-12-31T23:18:38Z

Warren moved page Fur Shader Layers to Fur Shader Passes

← Older revision

Revision as of 16:18, 31 December 2023

Warren at 23:04, 31 December 2023

2023-12-31T23:04:45Z

← Older revision		Revision as of 16:04, 31 December 2023
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	Almost nothing is rendered "correctly" by the fur layers. They take every short-cut possible, resulting in all sorts of lighting errors and glitches (if you know what to look for).		Almost nothing is rendered "correctly" by the fur layers. They take every short-cut possible, resulting in all sorts of lighting errors and glitches (if you know what to look for).

	However, speed is absolutely essential, because these layers make up the vast majority of the render time~~. Rendering~~ lots of "cheap" layers looks significantly better than rendering only half as many "expensive" layers.		However, speed is absolutely essential, because these layers make up the vast majority of the render time, and rendering lots of "cheap" layers looks significantly better than rendering only half as many "expensive" layers.

	The shader also has a couple of tricks up its sleeve:		The shader also has a couple of tricks up its sleeve:

Warren: /* Pass 2 - The Fur */

2023-12-31T23:04:23Z

Pass 2 - The Fur

← Older revision		Revision as of 16:04, 31 December 2023
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	Almost nothing is rendered "correctly" by the fur layers. They take every short-cut possible, resulting in all sorts of lighting errors and glitches (if you know what to look for).		Almost nothing is rendered "correctly" by the fur layers. They take every short-cut possible, resulting in all sorts of lighting errors and glitches (if you know what to look for).

	However, speed is absolutely essential, because these layers make up the vast majority of the render time. ~~Also, more speed means more~~ layers ~~can be rendered per frame, allowing the brute-force tactic of throwing more resolution at the screen to make the fur look~~ better.		However, speed is absolutely essential, because these layers make up the vast majority of the render time. Rendering lots of "cheap" layers looks significantly better than rendering only half as many "expensive" layers.

	The shader also has a couple of tricks up its sleeve:		The shader also has a couple of tricks up its sleeve:

Warren at 22:59, 31 December 2023

2023-12-31T22:59:47Z

← Older revision		Revision as of 15:59, 31 December 2023
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	Many lighting effects, such as proper specular lighting and normal maps, are simply too slow to calculate for every layer of fur. As a compromise, my shader only renders the skin "expensively".		Many lighting effects, such as proper specular lighting and normal maps, are simply too slow to calculate for every layer of fur. As a compromise, my shader only renders the skin "expensively".

	However, an unexpected benefit of rendering the skin ~~in a separate pass~~ is that it actually renders faster than doing everything in 1 pass. As far as I can tell (and is really just a guess!), trying to render the opaque skin at the same time as the mostly see-through fur results in the GPU caches missing a lot.		However, an unexpected benefit of rendering the skin separately is that it actually renders faster than doing everything in 1 pass. As far as I can tell (and is really just a guess!), trying to render the opaque skin at the same time as the mostly see-through fur results in the GPU caches missing a lot.

	The speed increase is so great, in fact, that 16 "cheap" fur layers + 1 "expensive" skin layer render significantly faster than 15 "cheap" fur layers + 1 "cheap" skin layer.		The speed increase is so great, in fact, that 16 "cheap" fur layers + 1 "expensive" skin layer render significantly faster than 15 "cheap" fur layers + 1 "cheap" skin layer.

Warren: /* Pass 2 - The Fur */

2023-12-31T22:59:15Z

Pass 2 - The Fur

← Older revision		Revision as of 15:59, 31 December 2023
Line 16:		Line 16:
	The shader also has a couple of tricks up its sleeve:		The shader also has a couple of tricks up its sleeve:

	* ~~Sneaky trick~~ #1: it can turn the fur off by having the Hull shader ask the Tessellator to multiply the number of triangles by 0, which throws them out~~. Any off-screen, far-away, or backwards-facing triangles are thus discarded~~ before the ~~expensive~~ Geometry shader stage ~~runs, which results in~~ a ~~massive~~ speed boost~~. Otherwise~~, ~~it tells~~ the ~~Tessellator to multiply the number~~ of ~~trianges by 1, which does nothing. The triangle is simply passed to~~ the ~~Geometry~~ shader ~~and thus the fur is rendered normally~~.		* Trick #1: it can turn the fur layers off (if too far away, offscreen, or backwards) by having the Hull shader ask the Tessellator to multiply the number of triangles by 0, which throws them out before they reach the Geometry shader stage. This is a MASSIVE speed boost, roughly doubling the speed of the shader.

	* ~~Sneaky trick~~ #2: it can have the Hull shader ask the Tessellator split each triangle into 4 when taking a photo. However, the Domain shader then ignores the Tessellator, and instead just makes 4 copies of the original, un-tessellated triangle. The fur can thus be rendered at up to 4x resolution, but only when needed.		* Trick #2: it can have the Hull shader ask the Tessellator split each triangle into 4 when taking a photo. However, the Domain shader then ignores the Tessellator, and instead just makes 4 copies of the original, un-tessellated triangle. The fur can thus be rendered at up to 4x resolution, but only when needed.

	== Pass 3 - The Overcoat ==		== Pass 3 - The Overcoat ==

Warren: /* Pass 1 - The Skin */

2023-12-31T22:53:48Z

Pass 1 - The Skin

← Older revision		Revision as of 15:53, 31 December 2023
Line 5:		Line 5:
	Many lighting effects, such as proper specular lighting and normal maps, are simply too slow to calculate for every layer of fur. As a compromise, my shader only renders the skin "expensively".		Many lighting effects, such as proper specular lighting and normal maps, are simply too slow to calculate for every layer of fur. As a compromise, my shader only renders the skin "expensively".

	However, an unexpected benefit of rendering the skin in a separate pass is that it actually renders faster than doing everything in 1 pass. As far as I can tell (and ~~this~~ really is just a guess!), ~~rending~~ the opaque skin at the same time as the mostly see-through fur results in the GPU caches missing a lot.		However, an unexpected benefit of rendering the skin in a separate pass is that it actually renders faster than doing everything in 1 pass. As far as I can tell (and is really just a guess!), trying to render the opaque skin at the same time as the mostly see-through fur results in the GPU caches missing a lot.

	The speed increase is so great, in fact, that ~~it more~~ than ~~offsets the speed decrease of rending the skin~~ "~~expensively~~".		The speed increase is so great, in fact, that 16 "cheap" fur layers + 1 "expensive" skin layer render significantly faster than 15 "cheap" fur layers + 1 "cheap" skin layer.

	== Pass 2 - The Fur ==		== Pass 2 - The Fur ==
Line 16:		Line 16:
	The shader also has a couple of tricks up its sleeve:		The shader also has a couple of tricks up its sleeve:

	Sneaky trick #1: it can turn the fur off by having the Hull shader ask the Tessellator to multiply the number of triangles by 0, which throws them out. Any off-screen, far-away, or backwards-facing triangles are thus discarded before the expensive Geometry shader stage runs, which results in a massive speed boost. Otherwise, it tells the Tessellator to multiply the number of trianges by 1, which does nothing. The triangle is simply passed to the Geometry shader and thus the fur is rendered normally.		* Sneaky trick #1: it can turn the fur off by having the Hull shader ask the Tessellator to multiply the number of triangles by 0, which throws them out. Any off-screen, far-away, or backwards-facing triangles are thus discarded before the expensive Geometry shader stage runs, which results in a massive speed boost. Otherwise, it tells the Tessellator to multiply the number of trianges by 1, which does nothing. The triangle is simply passed to the Geometry shader and thus the fur is rendered normally.

	Sneaky trick #2: it can have the Hull shader ask the Tessellator split each triangle into 4 when taking a photo. However, the Domain shader then ignores the Tessellator, and instead just makes 4 copies of the original, un-tessellated triangle. The fur can thus be rendered at up to 4x resolution, but only when needed.		* Sneaky trick #2: it can have the Hull shader ask the Tessellator split each triangle into 4 when taking a photo. However, the Domain shader then ignores the Tessellator, and instead just makes 4 copies of the original, un-tessellated triangle. The fur can thus be rendered at up to 4x resolution, but only when needed.

	== Pass 3 - The Overcoat ==		== Pass 3 - The Overcoat ==