Alamo Object Files (extension: .ALO) in Petroglyph's games describe a 3D model. It is a collection of bones, meshes with effects, proxies and dazzles. Alamo Object Files are an instance of Chunked Files.
Each Alamo Object File has a skeleton, several objects (meshes and/or lights) and a list of proxies and object connections.
Object files with this format are used in the game "Star Wars: Empire at War" and its expansion pack "Star Wars: Empire at War: Forces of Corruption."
This chunk is the container chunk for the skeleton of the model
dword numBones byte[124] zero
The first four bytes of this chunk are a 32-bit integer that hold the number of bone nodes in the skeleton. This chunk is always 128 bytes large, hence the padding.
This chunk is the container chunk for a bone in the skeleton
string name
This chunk holds the bone's name as an ASCIIZ string
int parent dword visible float4[3] matrix
This chunk holds the bone information. It is identical to the 0x206 bone type, but without the billboard field, which should be assumed to be zero.
int parent dword visible dword billboard float4[3] matrix
This chunk holds the bone information; the parent bone index (which is always less than this bone's index), whether or not the meshes and/or proxies attached to this bone (and its children) are visible, the billboard mode, and the transformation matrix. The matrix, stored row-wise, contains 3 rows of 4 columns each. After reading these rows, the 4th row should be (0,0,0,1) to create a transposed Direct3D-compatible 4x4 matrix that defines this bone's local transformation (i.e., relative to its parent).
This chunk is the container chunk for a mesh in the model.
This chunk contains the mesh's name as a single ASCIIZ string.
dword nMaterials float3[2] boundingBox dword unused dword isHidden dword isCollisionEnabled byte[88] zero
This chunk contains basic information about the mesh: the number of materials (sub-meshes; 0x10100 and 0x10000 chunk pairs) in this mesh, the bounding box for this mesh, whether this mesh is initially hidden and whether this mesh can be collided with (i.e., whether the mesh's sub-meshes have collision trees; 0x1200 chunks). The bounding box is stored as 6 floating point values: two X,Y,Z triples for the minimum and maximum points of the box, respectively. Note that this chunk is always 128 bytes large. Hence the zero padding.
This chunks contains chunks that identify the Direct3D Shader file to be used when rendering this mesh and its parameters. Shader parameters have a name, type and data and should be used with the GetParameterByName and SetInt, SetFloat, SetFloatArray, SetTexture, etc. functions.
This chunk contains the shader's filename as an ASCIIZ string. Note that this filename may reference the source file. To obtain the filename to the compiled effect file if the source file is not present, substitute the .fx extension with the .fxo extension.
01: string name 02: dword value
This chunk contains a shader parameter, of type INT. The parameter data is a single 32-bit signed integer. The name and data of the parameter are stored in mini chunks. The mini-chunk type of the name and parameter data is 01h and 02h, respectively.
01: string name 02: float value
This chunk contains a shader parameter, of type FLOAT. The parameter data is a single 32-bit IEEE 754 floating point value. The name and data of the parameter are stored in mini chunks. The mini-chunk type of the name and parameter data is 01h and 02h, respectively.
01: string name 02: float3 value
This chunk contains a shader parameter, of type FLOAT3. The parameter data is three consecutive 32-bit IEEE 754 floating point values. The name and data of the parameter are stored in mini chunks. The mini-chunk type of the name and parameter data is 01h and 02h, respectively.
01: string name 02: string value
This chunk contains a shader parameter, of type TEXTURE. The parameter data is the texture's filename as an ASCIIZ string. Note that this filename may reference the source file. To obtain the filename to the prepared texture file if the source file cannot be found, substitute the extension with the 'dds' extension. The name and data of the parameter are stored in mini chunks. The mini-chunk type of the name and parameter data is 01h and 02h, respectively.
01: string name 02: float4 value
This chunk contains a shader parameter, of type FLOAT4. The parameter data is four consecutive 32-bit IEEE 754 floating point values. The name and data of the parameter are stored in mini chunks. The mini-chunk type of the name and parameter data is 01h and 02h, respectively.
This chunk is the container chunk for the core sub-mesh data: vertices, indices, animation mappings and collision tree.
dword nVertices dword nPrimitives byte[120] zero
The first eight bytes of this chunks are two 32-bit integers that hold the number of vertices and triangles in the mesh, respectively. This chunk is always 128 bytes large, hence the padding.
string format
This chunk contains the format of the vertices that is desired by this sub-mesh as an ASCIIZ string. The vertex array always holds the same information while only a fraction may be used by the actual sub-mesh. This vertex format can be used as an index to set up a mapping to copy the desired bits of information from the vertex array in the file.
word[3 * nPrimitives] indices
This chunk contains the index buffer that is used to render the primitives of the mesh. The index buffer is an array of 16-bit indices into the vertex buffer located in the same 0x10000 node. The size of this chunk (in bytes) is equal to the number of primitives in the 0x10001 chunk times 6.
This chunk is a rare variant of the 0x10007 chunk, and also contains an array of vertices. However, each vertex is missing the "unused" field.
dword[1..24] bone
This chunk contains between 1 and 24 32-bit integers that are indices into the bones in the skeleton (0x200 chunk). During runtime, the actual values of these bones (which can change due to animations) must be passed to the renderer as the matrix palette for this sub-mesh.
float3 position float3 normal float2[4] texCoords float3 tangent float3 binormal float4 color float4 unused dword[4] boneIndices float[4] boneWeights
This chunk holds an array of vertices, where each vertex has the structure as described above. The number of vertices in this array is specified in the 0x10001 chunk. Note however, that although there is space for 4 bone-indices, only the first is every used. Therefore, boneWeights is always [1, 0, 0, 0]. These bone indices are indices into the animation mapping array (0x10006 chunk).
This chunk, which is only present if the mesh information (0x402) chunk's "isCollisionEnabled" field is non-zero, holds a spatial tree that can be traversed in logarithmic time with integer comparison to do collision detection.
00: float3 collisionBoxMin 01: float3 collisionBoxMax 02: dword nNodes 03: dword nPrimitives
This chunk contains four mini-chunks which describe the reference box for the collision detection (00 and 01 mini-chunks) and define the number of records in the 0x1202 and 0x1203 chunks (02 and 03 mini-chunks, respectively).
byte3 min byte3 max word nPrimitives word link
Each node is is associated with a sub-region of it's container box. The coordinates of this sub-box are stored as 8-bit values. These values are normalized to the volume of the node's parent box. In other words, the coordinate span (0,0,0) - (255,255,255) indicates the same box as the parent node. If nPrimitives is greater than zero, the link field points into the mapping array defined in the 0x1203 chunk and the nPrimitives value indicates how many subsequent triangles are contained in this leaf. If nPrimitives is zero, the link value points into this array, to the two children of this node. Therefore, the children of node #x are defined as the nodes with indices nodes[x].link and nodes[x].link + 1.
nodes[x].link
nodes[x].link + 1
word[nPrimitives] triangles
This chunk contains an array of 16-bit integers that map 1-on-1 to actual triangles in the model.
This chunks describes a single light object.
This chunks contains the light's name as an ASCIIZ string.
dword type float3 color float intensity float farAttenuationEnd float farAttenuationStart float hotspotSize float falloffSize
This chunk stores the light description as the values mentioned above. The type can be 0 (Omni light), 1 (Directional light) or 2 (Spotlight). The color is stored as an RGB triplet with each element in the range 0.0 - 1.0. Furthermore, the hotspotSize and falloffSize are both in radians.
This chunk is the container for the mapping that defines what bones meshes, lights and proxies are connected to.
01: dword nObjects 04: dword nProxies
This chunk contains two 32-bit integer mini-chunks of type 01h and 04h that indicate the number of 0x602 and 0x603 chunks, respectively.
02: dword object 03: dword bone
This chunk contains the index of a mesh or light object and the index of a bone to indicate that the specified mesh or light is connected to the position of the specified bone. Mesh/light indices are determined from the order in which the 0x400 and 0x600 chunks appeared in the file.
05: string proxy 06: dword bone 07: dword isHidden 08: dword altDecreaseStayHidden
This chunk contains the name of a proxy object and the index of a bone to indicate that the specified proxy object is connected to the specified bone. The isHidden and altDecreaseStayHidden values indicate if this proxy is initially hidden and if the "Alt Decrease Stay Hidden" property is set for this proxy.
This version extends the previous version with Alamo Dazzles.
Object files with this format are used in the game "Universe at War: Earth Assault."
01: dword nObjects 04: dword nProxies 09: dword nDazzles
This chunk contains three 32-bit integer mini-chunks of type 01, 04 and 09 that indicate the number of 0x602, 0x603 and 0x604 chunks, respectively.
00: float3 color 01: float3 position 02: float radius 03: dword slotX 04: dword slotY 06: string numSlots 05: dword texture 07: float frequency 08: float phase 09: dword nightOnly 0a: dword bone 0b: string name 0c: dword isHidden 0d: float bias
This chunk contains the information for a single dazzle object, including the index of a bone that the dazzle is connected to. The frequency, phase and bias properties determine the static, periodic visibility of the dazzle. The bias property is optional. slotX, slotY and numSlots determine the coordinates in the specified texture that should be used for a particle with a square size of 2 * radius. position is the relative offset from the bone of this dazzle. The isHidden property indicates if this dazzle is initially hidden.
