MIP MAP DEMO
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This demo shows the 4 different ways of rendering textures simultaneously
so they can be compared visually. The 4 views on the screen are:
TOP LEFT: Point Sampled
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Point sampled texture, no mip mapping. This works well when the
geometry is scaled so 1 pixel corresponds to exactly 1 texel. Due
to precision problems this only works really well with textured
rectangles.
TOP RIGHT: Bilinear Sampling
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Bilinear sampled textures. No mip mapping. This works well when
the texel to pixel ratio is close to 1:1. When the geometry gets
very small compared to the texture map on it then lots of flickering
occurs.
BOTTOM LEFT: RGB2C Mip Map
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Mip Mapping combined with bilinear sampling. The original texture was
fed to rgb2c which created all the mip map levels (the files named
RGBA16*MM.h). This works well when the geometry is small compered
to the size of the texture map (eg when the cube shrinks very small,
and on the faces which are very edge-on).
BOTTOM RIGHT: Hand Gen Mip Map
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Mip Mapping combined with bilinear sampling.
This demonstrates the ability to supply your own mip map levels. For
this texture the original texture AND all the filtered levels were
fed to rgb2c which created the mip map file with all the mip map levels
(the files named RGBA16*HMM.h). This is similar to rgba2c generated
mip mapping, but shows that when rgb2c doesn't filter the textures very
well you can do your own filtering. (I used Photoshop to shrink all
the images to the various sizes).
CONTROLS:
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The joystick controls the scale and position of the cube. Use the trigger
button to change the function of the joystick between scale, translate
x/z and translate x/y.
Use the L button (above the crosshair) to turn the menu on and off. Use the
crosshair Up and Down to select different menu items and the crosshair
left and Right to alter the values in the menu. Here are the parameters
which can be modified with the menu:
Texture: choose from among 5 textures (the 5th, #4, is actually the same
as #0 in the top level, #3 in the second level, #2 in the
third level, and #1 in the 4th level - Texture number 4 is
a special effect and would not normally be used like this).
Textures numbered 0 and #4 are 16x16 texels in their top level.
All other textures are 32x32 texels in their top level. All
textures are 16 bit RGB textures.
Control Rotation: set this to 1 to enable the joystick to rotate the
cube and move the walls. After setting this to 1, press the
trigger button until the message at the bottom of the screen
says "rotate object with joystick"
Rotation rate a: control how fast the object rotates.
Rotation rate b: control how fast the object rotates.
Texture Scale: alter the texture scale (changes the number of times the
texture repeats over each face).
Smallest Mip Pic: alter the number of levels of mip map used. This number
is the size (both s and t size in texels) of the smallest mipmap
used.
clamp lvl small or large: This only has effect when "Smallest Mip Pic" is
greater than 1. When the level of detail reaches the highest
level available (as set by "Smallest Mip Pic") then the texture
seen is either that level or the lowest level. (CHoose 1 for
that level and 0 for the lowest level).
The A button resets the position of the geometry.
-Acorn