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Properly Structured Arnold MTD Files
Immediately after a source code file has been successully compiled,
Cutter uses the oslinfo utility and parses
its output looking for metadata hints that may accompany each
input paremeter. For example, this shader,
shader
mkDonut(
float radius = 0.3,
float width = 0.1,
float u_center = 0.5
[[
string label = "U Center",
]],
float v_center = 0.5
[[
string label = "V Center",
]],
color bak_color = 1,
color pat_color = color(1,0,0),
float u_repeats = 4
[[
string label = "U Repetitions",
]],
float v_repeats = 4
[[
string label = "V Repetitions",
]],
float even_row_offset = 0,
output color resultRGB = 0)
{
float uu = mod(u * u_repeats, 1);
float vv = mod(v * v_repeats, 1);
float row = floor(v * v_repeats);
if(mod(row, 2) == 0)
uu = mod(u * v_repeats - even_row_offset, 1);
// Calculate the inner and outer circles
float inner_radius = radius - width/2;
float outer_radius = radius + width/2;
float a = uu - u_center;
float b = vv - v_center;
float dist = sqrt(a * a + b * b);
if(dist >= inner_radius && dist <= outer_radius)
resultRGB = pat_color;
else
resultRGB = bak_color;
}
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when compiled and processed
by oslinfo would generate the following data.
shader "mkDonut"
"radius" "float"
Default value: 0.3
"width" "float"
Default value: 0.1
"u_center" "float"
Default value: 0.5
metadata: string label = "U Center"
"v_center" "float"
Default value: 0.5
metadata: string label = "V Center"
"bak_color" "color"
Default value: [ 1 1 1 ]
"pat_color" "color"
Default value: [ 1 0 0 ]
"u_repeats" "float"
Default value: 4
metadata: string label = "U Repetitions"
"v_repeats" "float"
Default value: 4
metadata: string label = "V Repetitions"
"even_row_offset" "float"
Default value: 0
"resultRGB" "output color"
Default value: [ 0 0 0 ]
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After processing by Cutter the data is converted
into a mtd file named mkDonut.mtd.
[node mkDonut]
maya.name STRING "mkDonut"
maya.id INT 28
maya.classification STRING "Utility"
maya.output_name STRING "resultRGB"
maya.output_shortname STRING "resultRGB"
[attr radius]
default FLOAT 0.3
[attr width]
default FLOAT 0.1
[attr u_center]
default FLOAT 0.5
label STRING "U Center"
[attr v_center]
default FLOAT 0.5
label STRING "V Center"
[attr bak_color]
default COLOR 1 1 1
[attr pat_color]
default COLOR 1 0 0
[attr u_repeats]
default FLOAT 4
label STRING "U Repetitions"
[attr v_repeats]
default FLOAT 4
label STRING "V Repetitions"
[attr even_row_offset]
default FLOAT 0
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