aiMaterial.h File Reference

Defines the material system of the library. More...


Classes

struct  aiMaterial
 Data structure for a material. More...
struct  aiUVTransform
 Defines how an UV channel is transformed. More...

Enumerations

enum  aiBlendMode { aiBlendMode_Default = 0x0, aiBlendMode_Additive = 0x1 }
 Defines alpha-blend flags. More...
enum  aiShadingMode {
  aiShadingMode_Flat = 0x1, aiShadingMode_Gouraud = 0x2, aiShadingMode_Phong = 0x3, aiShadingMode_Blinn = 0x4,
  aiShadingMode_Toon = 0x5, aiShadingMode_OrenNayar = 0x6, aiShadingMode_Minnaert = 0x7, aiShadingMode_CookTorrance = 0x8,
  aiShadingMode_NoShading = 0x9, aiShadingMode_Fresnel = 0xa
}
 Defines all shading models supported by the library. More...
enum  aiTextureFlags { aiTextureFlags_Invert = 0x1, aiTextureFlags_UseAlpha = 0x2, aiTextureFlags_IgnoreAlpha = 0x4 }
 Defines some mixed flags for a particular texture. More...
enum  aiTextureMapMode { aiTextureMapMode_Wrap = 0x0, aiTextureMapMode_Clamp = 0x1, aiTextureMapMode_Decal = 0x3, aiTextureMapMode_Mirror = 0x2 }
 Defines how UV coordinates outside the [0. More...
enum  aiTextureMapping {
  aiTextureMapping_UV = 0x0, aiTextureMapping_SPHERE = 0x1, aiTextureMapping_CYLINDER = 0x2, aiTextureMapping_BOX = 0x3,
  aiTextureMapping_PLANE = 0x4, aiTextureMapping_OTHER = 0x5
}
 Defines how the mapping coords for a texture are generated. More...
enum  aiTextureOp {
  aiTextureOp_Multiply = 0x0, aiTextureOp_Add = 0x1, aiTextureOp_Subtract = 0x2, aiTextureOp_Divide = 0x3,
  aiTextureOp_SmoothAdd = 0x4, aiTextureOp_SignedAdd = 0x5
}
 Defines how the Nth texture of a specific type is combined with the result of all previous layers. More...
enum  aiTextureType {
  aiTextureType_NONE = 0x0, aiTextureType_DIFFUSE = 0x1, aiTextureType_SPECULAR = 0x2, aiTextureType_AMBIENT = 0x3,
  aiTextureType_EMISSIVE = 0x4, aiTextureType_HEIGHT = 0x5, aiTextureType_NORMALS = 0x6, aiTextureType_SHININESS = 0x7,
  aiTextureType_OPACITY = 0x8, aiTextureType_DISPLACEMENT = 0x9, aiTextureType_LIGHTMAP = 0xA, aiTextureType_REFLECTION = 0xB,
  aiTextureType_UNKNOWN = 0xC
}
 Defines the purpose of a texture. More...

Variables

struct aiUVTransform PACK_STRUCT
 Defines how an UV channel is transformed.


Detailed Description

Defines the material system of the library.


Enumeration Type Documentation

Defines alpha-blend flags.

If you're familiar with OpenGL or D3D, these flags aren't new to you. They define *how* the final color value of a pixel is computed, basing on the previous color at that pixel and the new color value from the material. The blend formula is:

    SourceColor * SourceBlend + DestColor * DestBlend
where <DestColor> is the previous color in the framebuffer at this position and <SourceColor> is the material colro before the transparency calculation.
This corresponds to the AI_MATKEY_BLEND_FUNC property.
Enumerator:
aiBlendMode_Default  Formula:.

  SourceColor*SourceAlpha + DestColor*(1-SourceAlpha)
aiBlendMode_Additive  Additive blending.

Formula:

  SourceColor*1 + DestColor*1

Defines all shading models supported by the library.

The list of shading modes has been taken from Blender. See Blender documentation for more information. The API does not distinguish between "specular" and "diffuse" shaders (thus the specular term for diffuse shading models like Oren-Nayar remains undefined).
Again, this value is just a hint. Assimp tries to select the shader whose most common implementation matches the original rendering results of the 3D modeller which wrote a particular model as closely as possible.

Enumerator:
aiShadingMode_Flat  Flat shading.

Shading is done on per-face base, diffuse only. Also known as 'faceted shading'.

aiShadingMode_Gouraud  Simple Gouraud shading.
aiShadingMode_Phong  Phong-Shading -.
aiShadingMode_Blinn  Phong-Blinn-Shading.
aiShadingMode_Toon  Toon-Shading per pixel.

Also known as 'comic' shader.

aiShadingMode_OrenNayar  OrenNayar-Shading per pixel.

Extension to standard Lambertian shading, taking the roughness of the material into account

aiShadingMode_Minnaert  Minnaert-Shading per pixel.

Extension to standard Lambertian shading, taking the "darkness" of the material into account

aiShadingMode_CookTorrance  CookTorrance-Shading per pixel.

Special shader for metallic surfaces.

aiShadingMode_NoShading  No shading at all.

Constant light influence of 1.0.

aiShadingMode_Fresnel  Fresnel shading.

Defines some mixed flags for a particular texture.

Usually you'll instruct your cg artists how textures have to look like ... and how they will be processed in your application. However, if you use Assimp for completely generic loading purposes you might also need to process these flags in order to display as many 'unknown' 3D models as possible correctly.

This corresponds to the AI_MATKEY_TEXFLAGS property.

Enumerator:
aiTextureFlags_Invert  The texture's color values have to be inverted (componentwise 1-n).
aiTextureFlags_UseAlpha  Explicit request to the application to process the alpha channel of the texture.

Mutually exclusive with aiTextureFlags_IgnoreAlpha. These flags are set if the library can say for sure that the alpha channel is used/is not used. If the model format does not define this, it is left to the application to decide whether the texture alpha channel - if any - is evaluated or not.

aiTextureFlags_IgnoreAlpha  Explicit request to the application to ignore the alpha channel of the texture.

Mutually exclusive with aiTextureFlags_UseAlpha.

Defines how UV coordinates outside the [0.

..1] range are handled.

Commonly refered to as 'wrapping mode'.

Enumerator:
aiTextureMapMode_Wrap  A texture coordinate u|v is translated to u1|v1.
aiTextureMapMode_Clamp  Texture coordinates outside [0.

..1] are clamped to the nearest valid value.

aiTextureMapMode_Decal  If the texture coordinates for a pixel are outside [0.

..1] the texture is not applied to that pixel

aiTextureMapMode_Mirror  A texture coordinate u|v becomes u1|v1 if (u-(u1))2 is zero and 1-(u1)|1-(v1) otherwise.

Defines how the mapping coords for a texture are generated.

Real-time applications typically require full UV coordinates, so the use of the aiProcess_GenUVCoords step is highly recommended. It generates proper UV channels for non-UV mapped objects, as long as an accurate description how the mapping should look like (e.g spherical) is given. See the AI_MATKEY_MAPPING property for more details.

Enumerator:
aiTextureMapping_UV  The mapping coordinates are taken from an UV channel.

The AI_MATKEY_UVWSRC key specifies from which UV channel the texture coordinates are to be taken from (remember, meshes can have more than one UV channel).

aiTextureMapping_SPHERE  Spherical mapping.
aiTextureMapping_CYLINDER  Cylindrical mapping.
aiTextureMapping_BOX  Cubic mapping.
aiTextureMapping_PLANE  Planar mapping.
aiTextureMapping_OTHER  Undefined mapping.

Have fun.

Defines how the Nth texture of a specific type is combined with the result of all previous layers.

Example (left: key, right: value):

  DiffColor0     - gray
  DiffTextureOp0 - aiTextureOpMultiply
  DiffTexture0   - tex1.png
  DiffTextureOp0 - aiTextureOpAdd
  DiffTexture1   - tex2.png
Written as equation, the final diffuse term for a specific pixel would be:
  diffFinal = DiffColor0 * sampleTex(DiffTexture0,UV0) + 
     sampleTex(DiffTexture1,UV0) * diffContrib;
where 'diffContrib' is the intensity of the incoming light for that pixel.
Enumerator:
aiTextureOp_Multiply  T = T1 * T2.
aiTextureOp_Add  T = T1 + T2.
aiTextureOp_Subtract  T = T1 - T2.
aiTextureOp_Divide  T = T1 / T2.
aiTextureOp_SmoothAdd  T = (T1 + T2) - (T1 * T2).
aiTextureOp_SignedAdd  T = T1 + (T2-0.5).

Defines the purpose of a texture.

This is a very difficult topic. Different 3D packages support different kinds of textures. For very common texture types, such as bumpmaps, the rendering results depend on implementation details in the rendering pipelines of these applications. Assimp loads all texture references from the model file and tries to determine which of the predefined texture types below is the best choice to match the original use of the texture as closely as possible.

In content pipelines you'll usually define how textures have to be handled, and the artists working on models have to conform to this specification, regardless which 3D tool they're using.

Enumerator:
aiTextureType_NONE  Dummy value.

No texture, but the value to be used as 'texture semantic' (aiMaterialProperty::mSemantic) for all material properties *not* related to textures.

aiTextureType_DIFFUSE  The texture is combined with the result of the diffuse lighting equation.
aiTextureType_SPECULAR  The texture is combined with the result of the specular lighting equation.
aiTextureType_AMBIENT  The texture is combined with the result of the ambient lighting equation.
aiTextureType_EMISSIVE  The texture is added to the result of the lighting calculation.

It isn't influenced by incoming light.

aiTextureType_HEIGHT  The texture is a height map.

By convention, higher gray-scale values stand for higher elevations from the base height.

aiTextureType_NORMALS  The texture is a (tangent space) normal-map.

Again, there are several conventions for tangent-space normal maps. Assimp does (intentionally) not distinguish here.

aiTextureType_SHININESS  The texture defines the glossiness of the material.

The glossiness is in fact the exponent of the specular (phong) lighting equation. Usually there is a conversion function defined to map the linear color values in the texture to a suitable exponent. Have fun.

aiTextureType_OPACITY  The texture defines per-pixel opacity.

Usually 'white' means opaque and 'black' means 'transparency'. Or quite the opposite. Have fun.

aiTextureType_DISPLACEMENT  Displacement texture.

The exact purpose and format is application-dependent. Higher color values stand for higher vertex displacements.

aiTextureType_LIGHTMAP  Lightmap texture (aka Ambient Occlusion).

Both 'Lightmaps' and dedicated 'ambient occlusion maps' are covered by this material property. The texture contains a scaling value for the final color value of a pixel. Its intensity is not affected by incoming light.

aiTextureType_REFLECTION  Reflection texture.

Contains the color of a perfect mirror reflection. Rarely used, almost never for real-time applications.

aiTextureType_UNKNOWN  Unknown texture.

A texture reference that does not match any of the definitions above is considered to be 'unknown'. It is still imported, but is excluded from any further postprocessing.


Variable Documentation

Defines how an UV channel is transformed.

This is just a helper structure for the AI_MATKEY_UVTRANSFORM key. See its documentation for more details.

Typically you'll want to build a matrix of this information. However, we keep separate scaling/translation/rotation values to make it easier to process and optimize UV transformations internally.


Generated on Sat Apr 17 18:41:24 2010 for Assimp by  doxygen 1.5.8