From 095b7e513f736567848173f2572d8b329ad75af9 Mon Sep 17 00:00:00 2001 From: Travis CI Date: Thu, 19 Mar 2015 19:32:08 +0000 Subject: Gem 206d71791bc3642e8c5391a4c59c30ba7411fab8 osx/x86_64 built 'coverity_scan:206d71791bc3642e8c5391a4c59c30ba7411fab8' for osx/x86_64 --- Gem/manual/Texture.html | 126 ------------------------------------------------ 1 file changed, 126 deletions(-) delete mode 100644 Gem/manual/Texture.html (limited to 'Gem/manual/Texture.html') diff --git a/Gem/manual/Texture.html b/Gem/manual/Texture.html deleted file mode 100644 index 1de889c..0000000 --- a/Gem/manual/Texture.html +++ /dev/null @@ -1,126 +0,0 @@ - - - - - - - Texture mapping - - - -
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-Texture Mapping

-Texture mapping is the act of applying -pixel data to a geometric object. In GEM, this is achieved with the -[pix_texture] -object. It is important to understand that the -[pix_texture] -object merely sets the pix as the current texture. It does not do -any rendering! You need to use a geo object which does texture mapping. -All of the basic geo objects can texture map, such as [square] or -[sphere]. -

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A simple example of texture mapping is the following patch: -

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This patch can be found at 07.texture/01.texture.pd. Change -the number box connected to the rotate object to see what a texture map -on a cube looks like. -

The [pix_image] object loads in the fractal image file. The -[pix_texture] -object says that the pix data should be used as a texture map. Notice -that this is different than the previous manual section when we used the -[pix_draw] object. The final object in the chain is the [cube] -object. Because we have enabled texture mapping with the [pix_texture] -object, the cube takes the pix data and applies it to the geometry. -

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Texture mapping can be used with any GEM object. In the previous -manual section, you saw how to load in pix data with a variety of objects, -including [pix_multiimage] and [pix_video]. All of these -objects can be used with the [pix_texture] object. -

Because the pix data is applied to geometry, you can move, rotate, and -scale the image. This is extremely useful on the [square] object. -Instead of doing a one-to-one pixel mapping as occurs with the [pix_draw] -object, you can resize and reshape the image. -

OpenGL originally required that images must have dimensions that are power-of-2, such as 64, 128, or 256. This restriction has been released with recent gfx-cards -(like some radeon/nvidia products). -However, if the width or height of an image is not a power of two, -then the [pix_texture] object will take care of this, -and still render it (depending on you hardware with some tricks). -You can thus texture images of any size, but since this is based on tricking -the texture-coordinates, [pix_coordinate] might not give the wanted result any more. -

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The example patch 07.texture/02.moveImages.pd is a much more complex -patch which uses alpha blending to create a transparent object, in this -case, the dancer. Make sure to turn on the rotation with the [metro] -object. -

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People have been asking how textures are handled in GEM. Here -is a long explanation from an email which I wrote. -

Here is how textures are dealt with under OpenGL and hardware -accelerators. This can obviously change in the future, but right -now, I am fairly certain that the info is correct (I make games in my day -job, so I have vested interest in this :-) -

The amount of memory (VRAM) on the card (12mb for Voodoo2, -16mb for TNT, 64mb for GeForce2, etc) is used for both textures (TRAM) -and frame buffer space. If you have a large rendering window, like -1600x1200, it will take up 1600x1200x4x3 in 32-bit mode with double buffering -and a Z buffer (or 23mb). Most people run at TV resolution, like -NTSC, so it takes 640x480x4x3 = 3.7mb All of the space left -is for textures onboard the card (FYI, if you have heard that people are -having problems with the PlayStation2, notice that it only has 4mb of VRAM...not -much onboard texture space, huh? :-) Thankfully it has an extremely -fast DMA bus) -

Sooo, when GEM "creates" a texture, it immediately tries -to send the texture to the card, which uses some of the left over space -in the VRAM. If you had a 640x480 window on a Voodoo2, you have ~8mb -of texture space left over. On a GeForce2, ~60mb. The problem -is what happens if you want more textures than can fit into TRAM. -OpenGL requires that the video drivers deal with the problem, so GEM doesn't -care too much (more about this later). -

In most cases, the drivers cache the textures in main memory -and if a texture is requested for rendering and it isn't resident on the -card, it will download it. If you have AGP, then this is pretty quick, -although none of 3dfx cards really take advantage of this (ie, those cards -are about the same speed as the PCI bus). So depending on the number -of textures, and how complex the scene is, you might be able to display -more textures than you have TRAM. -

One slowdown that can happen with GEM is that it makes a -copy of the image before sending it down the chain of objects. If -you are constantly changing images with a pix_multiimage, this can be a -performance hit, but you can modify the actual pixel data with the pix -objects. The pixels aren't sent to the graphics card until the pix_texture -object is reached. -

GEM tries to help with this with a few objects. pix_imageInPlace -acts much the same as pix_multiimage, but it downloads _every_ image in -the sequence to the card when a download message is recieved. It -also immediately turns on texturing, instead of making a copy (ie, you -don't need a pix_texture object). Much faster, but not as flexible. -pix_movie does much the same thing. It sends the pixel data without -copying it if there is a new frame to display. -

The entire pix system uses a caching system so that the copying -and processing only occurs if something actually changes. For example, -if you had a pix_threshold object, it would only process when rendering -started...and every time that the values actually changed. You can -use pix_buf to isolate parts which don't change from those that do, but -it involves another copy. -

On the Voodoo2, the hardware itself limits textures to 256x256...this -will never change. The newest Voodoo5 boards have a higher texture -size. -

If you load the _exact_ same image (this means the exact -same file/path name), then the pix_image has a cache system which means -that it is only loaded into the -
computers memory once. However, each pix_image still sends -its own copy down to the gfx card. -

You could use a single [pix_image]/[pix_texture] with [separator] -to do this...I have done it a lot in the past. -

The reason that [pix_image] doesn't share the actual texture -data is that you can modify the pixel data with other pix objects...[pix_image] -doesn't actually send the texture data to the gfx card, [pix_texture] does. -

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