Materials
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Materials
The best way to get information on materials is starting to read the manual. Material Scripts
Attached is a collection of material templates that can be used as the launching pad for your own OGRE projects. Programmatic materials - e.g. materials created systematically via C++ code - can be found here.
Get Syntax highlighting for Material files using Crimson Editor.
Basic
Simple image map
The simplest material - apply an image to a mesh.
Material Requirements
- image.png - Texture
Material Template
material Template/texture_map
{
technique
{
pass
{
texture_unit
{
texture image.png
scale 0.1 0.1
// this means that the texture will be tiled 10 times (1/10 = 0.1)
}
}
}
}
Solid colour
Use a script like this to create a solid coloured material:
Material Template
material Template/Red
{
technique
{
pass
{
texture_unit
{
colour_op_ex source1 src_manual src_current 1 0 0
}
}
}
}
'source1' uses the first source without modifications. In this case, the first source is the very next argument. 'src_manual' means to use the colour denoted by the three numbers at the end. The numbers represent RGB values and can be between 0 and 1. 'src_current' is the texture_unit that is being blended with 'src_manual', but in this case, since the operation is to use the first source unchanged, the resulting texture is simply the solid color as denoted by '1 0 0'.
Transparent colour
Use a script like this to create a transparent colour material:
Material Template
material Template/Red50
{
technique
{
pass
{
scene_blend alpha_blend
depth_write off
texture_unit
{
colour_op_ex source1 src_manual src_current 1 0 0
alpha_op_ex source1 src_manual src_current 0.5
}
}
}
}
The 'colour_op_ex' line is explained above. The 'alpha_op_ex' has the same argument structure, the only difference is that the value at the end specifies the alpha value to use. Here, the colour is being set to 50% transparent. You can experiment with different arguments for scene_blend to give the material different kinds of transparency.
Simple texture transition
Suppose you have three quads representing a ground plane. Quad A you want to be dirt, Quad B you want to be a combination of dirt and grass, and finally quad C is grass. Here is a simple material for Quad B that does not require external creation of a dirt/grass texture.
Material Requirements
- the blending file must be in 8 bit format (24 bit doesn't work)
- be shure that you really save the following images itself (and not the target page)
- Material_grass.png - Source texture
- Material_dirt.jpg - Desination texture
- Material_alpha_blend.png - A PNG file that has the alpha mask we want to borrow for the transition.
The Rule of blending image: The black (or color) area will be the source texture, and the transparent area will be destination texture
Material Template
material Template/texture_blend
{
technique
{
pass
{
texture_unit
{
texture Material_grass.png
}
texture_unit
{
texture Material_alpha_blend.png
colour_op alpha_blend
}
texture_unit
{
texture Material_dirt.jpg
colour_op_ex blend_current_alpha src_texture src_current
}
}
}
}
The result
Pro: Easy, no programming required
Con: You have to build a new transition material for each transition you would like.
Advanced Tip: See Alpha Splatting.
Dynamic texture transition
You can programatically control the amount of grass/dirt shown with some minor adjustments to the above example.
Dynamic Material Template
material dynamic_texture_blend
{
technique
{
pass
{
texture_unit
{
texture Material_grass.png
}
}
pass
{
scene_blend alpha_blend
texture_unit
{
texture Material_alpha_blend.png
//The alpha_op for this texunit is programatically set, see below
//alpha_op_ex modulate src_manual src_texture SOME_NUMBER
}
texture_unit
{
texture Material_dirt.jpg
colour_op_ex blend_current_alpha src_texture src_current
}
}
}
}
Then in your source code:
Ogre::MaterialPtr materialPtr = Ogre::MaterialManager::getSingleton().getByName("dynamic_texture_blend");
Ogre::TextureUnitState* ptus = materialPtr->getTechnique(0)->getPass(1)->getTextureUnitState(0); //2nd pass, first texture unit
ptus->setAlphaOperation(Ogre::LBX_MODULATE, Ogre::LBS_MANUAL, Ogre::LBS_TEXTURE, your_transparency_level_varaible_goes_here);
Stained Glass Window
Suppose you have a quad, and you want it to be partially transparent, much like a stained glass window.
Material Requirements
- image.png - Texture you want to be transparent
Material Template
material Template/TransparentTexture
{
technique
{
pass
{
lighting off
scene_blend alpha_blend
depth_write off
texture_unit
{
texture image.png
alpha_op_ex source1 src_manual src_texture 0.5
}
}
}
}
Transparent map
Suppose you have a alpha-masked texture of a tree, and you want to apply this texture to a quad.
Material Requirements
- image.png - An image with an alpha layer that dictates what part of the image should be visible (and by how much)
Material Template
material cutout
{
technique
{
pass
{
lighting off
ambient 1 1 1 1
diffuse 1 1 1 1
specular 0 0 0 0
emissive 0 0 0
scene_blend alpha_blend
depth_write off
texture_unit
{
texture image.png
tex_coord_set 0
colour_op modulate
}
}
}
}
Note: This material script was produced by the maya6.0e exporter. It may contain more information than is necessary. However, If we use this script for many object nearby each other, we will get problem like this Blending scene problem. So, this is the script we can use if we want to make many object with transparent near each other like a forest.
Material Template
material cutout
{
technique
{
pass
{
lighting off
ambient 1 1 1 1
diffuse 1 1 1 1
specular 0 0 0 0
emissive 0 0 0
alpha_rejection greater 128 // by increase this number, we will get more transparent objects
depth_write on
texture_unit
{
texture image.png
tex_coord_set 0
colour_op modulate
}
}
}
}
Chroma Key
Quoted from OGRE MVP Christian "DWORD" Larsen: "It's not possible really, unless you use shaders or modify your textures dynamically. You're better off saving your textures in a format containing an alpha channel."
Quoted from OGRE Project Lead sinbad: "Colour keying went out with palettised textures and other dinosaur techniques Wink Alpha channels are in." HAve a look at thisforum thread.
Alternatively, you could use this function: Creating transparency based on a key colour in code
Old Chroma key info below:
Suppose you have a texture with no alpha-layer and you want to make all pixels of a given color (be it green, blue, etc) transparent in the texture.
Material Requirements
- An RGB color - say (0,255,0) for green
- image.png - An image with the RGB color applied as the alpha mask
Material Template
TO DO
Porcelain and Steel shader
This shader can be used to made porcelain or steel objects based on environment maps. First step, create an environment map. That is the map that your object will reflect.
And this is the shader:
material porcelainshad
{
technique
{
pass
{
ambient 1.0 1.0 1.0
diffuse 1.0 1.0 1.0
specular 1.0 1.0 1.0 9800.0
emissive 0.0 0.0 0.0 1
texture_unit
{
texture env_room.jpg
color_op_ex blend_manual src_texture src_current 0.1
env_map spherical
}
}
}
}
env_room is the environment map. With
specular 1.0 1.0 1.0 9800.0
we have the Porcelain shader
And with steel shader, increase the specular
specular 0.9 0.9 0.9 10000.0
Lightmap
A lightmap is just a texture for blending in OGRE. Normally, the lightmap texture is a grayscale texture like this
lightmap.jpg
The black area will be the shadowed and in the white are, the obejct will be illuminated. And we have material:
rock.jpg
And we will blend them like this:
material rock_lightmap
{
technique
{
pass
{
ambient 1.0 1.0 1.0
diffuse 1.0 1.0 1.0
specular 1.0 1.0 1.0 9800.0
emissive 0.0 0.0 0.0 1
texture_unit
{
texture rock.jpg // the detail texture
tex_coord_set 0 // UV set for the detail map (if you have multi-UV)
colour_op modulate
}
}
pass
{
scene_blend modulate
texture_unit
{
lightmap.jpg // the lightmap texture
tex_coord_set 0 // UV set for the lightmap (if you have multi-UV)
colour_op modulate
}
}
}
}
And the result of the blending:
Some advanced points: If you create multi UV for model in 3D program, you have to set their UV set in tex_coord_set. You can check the .XML file for more information.
vertexbuffer positions="true" normals="true" colours_diffuse="true" colours_specular="false" texture_coords="1"
The .MESH file converted from .XML will contain these information too.
Intermediate Materials
Detail Textures
TO DO
Advanced Materials
Alpha Splatting
This technique is used to allow multiple detail textures to be blended over each other according to an alpha map, that determines for each texture, where it is to be put. This is most often used for terrain, where you have many different undergrounds like dirt, walkways, grass, stone etc. This cannot be done with one pre-rendered texture, because it would require too much texture memory or look too coarse grained otherwise.
Material Requirements
-
A mesh, for instance a landscape
-
A uvmap for the mesh
-
A texture containing the alpha map (this texture can contain colour channel informations, but it is ignored)
-
detail textures for each underground type
Material Template
material Material/SOLID/erdboden.jpg
{
receive_shadows on
technique
{
// base pass
pass
{
// no lighting
lighting off
texture_unit
{
// we use the grass texture as the base, other textures are blended over it
texture grass.jpg
// scale the texture so, that it looks nice
scale 0.1 0.1
// only blend colour
// colour_op_ex source1 src_texture src_texture
}
}
// dirt pass
pass
{
// no lighting
lighting off
// blend with former pass
scene_blend alpha_blend
// only overwrite fragments with the same depth
depth_func equal
// alpha map for the dirt
texture_unit
{
texture alpha_dirt.png
// use alpha from this texture
alpha_op_ex source1 src_texture src_texture
// and colour from last pass
colour_op_ex source2 src_texture src_texture
}
// detail texture
texture_unit
{
texture dirt.jpg
scale 0.15 0.15
// alpha blend colour with colour from last pass
colour_op_ex blend_diffuse_alpha src_texture src_current
}
}
// ... further detail passes like the former one ...
// lighting pass
pass
{
ambient 0.5 0.5 0.5 1
diffuse 0.3 0.3 0.3
depth_func equal
scene_blend zero src_colour
}
}
}
BumpMapping
First of all, Dot3Bump is a perfect example for bump mapping.
Here are my 3 examples files:
SolPSDNet.png: color texture
SolPSDNetbump.png: bump texture
SolPSDNetb.png: normal map obtained with bump texture
STEP 1 : Convert bump to normal map
I only found this for photoshop users. You will need a plug-in for photoshop by Nvidia: 'NVIDIA Normal Map Filter' (Go here(Nvidia site) and search for: "Normal Map Filter", you'll find in first results).
Load your bump map in photoshop and go to filter/nvidia tool and normal map. Play around with the scale parameter for stronger effects.
After conversion, save your file as "SolPSDNetb.png" for example.
STEP 2 : Read example-advancedmaterial
Find example-advanced.material and look for Examples/BumpMapping/MultiLight section. Copy and paste it to your .material file.
Here is the code:
material Examples/BumpMapping/MultiLight
{
// this is the preferred technique which uses both vertex and
// fragment programs and supports coloured lights
technique
{
// base ambient pass
pass
{
// base colours, not needed for rendering, but as information
// to lighting pass categorisation routine
ambient 1 1 1
diffuse 0 0 0
specular 0 0 0 0
// really basic vertex program
// NB we don't use fixed functions here because GL does not like
// mixing fixed functions and vertex programs (depth fighting can
// be an issue)
vertex_program_ref Ogre/BasicVertexPrograms/AmbientOneTexture
{
param_named_auto worldViewProj worldviewproj_matrix
param_named_auto ambient ambient_light_colour
}
}
// wow do the lighting pass
// NB we don't do decal texture here because this is repeated per light
pass
{
// base colours, not needed for rendering, but as information
// to lighting pass categorisation routine
ambient 0 0 0
// do this for each light
iteration once_per_light
scene_blend add
// vertex program reference
vertex_program_ref Examples/BumpMapVP
{
param_named_auto lightPosition light_position_object_space 0
param_named_auto worldViewProj worldviewproj_matrix
}
// fragment program
fragment_program_ref Examples/BumpMapFP
{
param_named_auto lightDiffuse light_diffuse_colour 0
}
// base bump map
texture_unit
{
texture NMBumpsOut.png
colour_op replace
}
// normalisation cube map
texture_unit
{
cubic_texture nm.png combinedUVW
tex_coord_set 1
tex_address_mode clamp
}
}
// decal pass
pass
{
// base colours, not needed for rendering, but as information
// to lighting pass categorisation routine
lighting off
// really basic vertex program
// NB we don't use fixed function here because GL does not like
// mixing fixed function and vertex programs (depth fighting can
// be an issue)
vertex_program_ref Ogre/BasicVertexPrograms/AmbientOneTexture
{
param_named_auto worldViewProj worldviewproj_matrix
param_named ambient float4 1 1 1 1
}
scene_blend dest_colour zero
texture_unit
{
texture RustedMetal.jpg
}
}
}
// this is the fallback which cards which don't have fragment program
// support will use
// Note: this still requires vertex program support
technique
{
// base ambient pass
pass
{
// base colours, not needed for rendering, but as information
// to lighting pass categorisation routine
ambient 1 1 1
diffuse 0 0 0
specular 0 0 0 0
// really basic vertex program
// NB we don't use fixed function here because GL does not like
// mixing fixed function and vertex programs (depth fighting can
// be an issue)
vertex_program_ref Ogre/BasicVertexPrograms/AmbientOneTexture
{
param_named_auto worldViewProj worldviewproj_matrix
param_named_auto ambient ambient_light_colour
}
}
// now do the lighting pass
// NB we don't do decal texture here because this is repeated per light
pass
{
// base colours, not needed for rendering, but as information
// to lighting pass categorisation routine
ambient 0 0 0
// do this for each light
iteration once_per_light
scene_blend add
// vertex program reference
vertex_program_ref Examples/BumpMapVP
{
param_named_auto lightPosition light_position_object_space 0
param_named_auto worldViewProj worldviewproj_matrix
}
// base bump map
texture_unit
{
texture NMBumpsOut.png
colour_op replace
}
// normalisation cube map, with dot product on bump map
texture_unit
{
cubic_texture nm.png combinedUVW
tex_coord_set 1
tex_address_mode clamp
colour_op_ex dotproduct src_texture src_current
colour_op_multipass_fallback dest_colour zero
}
}
// decal pass
pass
{
lighting off
// really basic vertex program
// NB we don't use fixed function here because GL does not like
// mixing fixed function and vertex programs, depth fighting can
// be an issue
vertex_program_ref Ogre/BasicVertexPrograms/AmbientOneTexture
{
param_named_auto worldViewProj worldviewproj_matrix
param_named ambient float4 1 1 1 1
}
scene_blend dest_colour zero
texture_unit
{
texture RustedMetal.jpg
}
}
}
}
After that, you can find the "header" of CG program in the same example-advanced.material file (only copy CG program header for bump maping):
// bump map vertex program, support for this is required
vertex_program Examples/BumpMapVP cg
{
source Example_BumpMapping.cg
entry_point main_vp
profiles vs_1_1 arbvp1
}
// bump map fragment program, support for this is optional
fragment_program Examples/BumpMapFP cg
{
source Example_BumpMapping.cg
entry_point main_fp
profiles ps_1_1 arbfp1 fp20
}
// bump map with specular vertex program, support for this is required
vertex_program Examples/BumpMapVPSpecular cg
{
source Example_BumpMapping.cg
entry_point specular_vp
profiles vs_1_1 arbvp1
}
// bump map fragment program, support for this is optional
fragment_program Examples/BumpMapFPSpecular cg
{
source Example_BumpMapping.cg
entry_point specular_fp
profiles ps_1_1 arbfp1 fp20
}
Copy and paste the headers at the beginning of your .material file.
STEP 3 : Lat work, include your textures
You have to replace the following in your .material :
RustedMetal.jpg by your color map SolPSDNet.png
NMBumpsOut.png by your NORMAL MAP (not bump) SolPSDNetb.png
And thats all folks!
Important Hint: To use bumpmapping, we'll need tangent vectors for our meshes.
OGRE can do this for you ahead of time if you use the '-t' parameter to the command line tools OgreXmlConverter or OgreMeshUpgrade. Otherwise, you can generate them in code like this:
// load the meshes with non-default HBU options
MeshPtr pMesh = MeshManager::getSingleton().load("Block02.mesh",
ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME,
HardwareBuffer::HBU_DYNAMIC_WRITE_ONLY,
HardwareBuffer::HBU_STATIC_WRITE_ONLY,
true, true);
// so we can still read it
// build tangent vectors, all our meshes use only one texture coordset
// Note: we can build into VES_TANGENT now (SM2+)
unsigned short src, dest;
if (!pMesh->suggestTangentVectorBuildParams(VES_TANGENT, src, dest))
{
pMesh->buildTangentVectors(VES_TANGENT, src, dest);
}
Read also BumpMapping in this wiki.
Manual
Also have a look in the OGRE manual
