A few more .idx realisations, and some parsing code

cmd/loader/main.go

@@ -201,8 +201,12 @@ func loadFonts() {
 
 func loadIdx() {
 	idxPath := filepath.Join(*gamePath, "Idx", "WarHammer.idx")
-	_, err := idx.Load(idxPath)
+	idx, err := idx.Load(idxPath)
 	if err != nil {
 		log.Fatalf("Failed to parse %s as idx: %v", idxPath, err)
 	}
+
+	for i, group := range idx.Groups {
+		log.Printf("Group %2d: %4d records, start sprite is %6d", i, len(group.Records), group.Spec.SpriteIdx)
+	}
 }

doc/formats/ani.md

@@ -309,11 +309,14 @@ matches the value at offset 8. This, then, must be the link.
 
 If the first sprite is 0, the displayed sprite is 64 (`0x40`)...
 
+We still need to know how to go from "librarian" to "index 11", though. The
+`CTYPE_LIBRARIAN` value in `HasAction.ani` gives librarians an 8...
+
 
 | Offset | Size | Meaning |
 | ------ | ---- | ------- |
-| 0      | 4    | Offset of type 2 record(s) |
-| 4      | 4    | Unknown |
+| 0      | 4    | Offset of type 2 records |
+| 4      | 4    | Number of type 2 records |
 | 8      | 4    | First sprite in `WarHammer.ani` for this record |
 
 ### Type 2 record(s)
@@ -334,7 +337,8 @@ Next, we read 5x 12-byte records - 60 bytes total - from that offset in the type
 the reads of type 2 records stop - so we were searching for it.
 
 In the first 12-byte record, we have a close offset: `0x098350`. So we have
-1,824 bytes available in this block of type 2 records - enough for 152 of them.
+1,824 bytes available in this block of type 2 records - enough for 152 of them,
+which is the number specified in the second position of the type 1 header.
 
 What is the significance of the fifth 12-byte read? Why do we move onto type 3
 records when we reach it? When we place the librarian, he is **facing** south,
@@ -354,7 +358,7 @@ total, but I haven't counted the actions yet.
 
 | Offset | Size | Meaning |
 | ------ | ---- | ------- |
-| 0      | 2?   | Static per each group of 8 type-2 records? |
+| 0      | 2?   | ActionID? Static per each group of 8 type-2 records? |
 | 2      | 1?   | Counts up from `01` to `08` in each group of 8 type-2 records? |
 | 3      | 1?   | Is `0x33` for all but the last 4 groups of 8 type-2 records? |
 | 4      | 4    | Position of type 3 record |
@@ -386,9 +390,13 @@ offsets of the frames we load.
 | ------ | ---- | ------- |
 | 0      | 2    | First sprite in animation (relative offset) |
 | 2      | 2    | Last sprite in animation (relative offset)?  |
-| 4      | 2?    | Could also be last sprite in animation? |
-| 6      | 2?    | ??? |
-| 8      | 12?   | ??? - unset in this case |
+| 4      | 2?   | Could also be last sprite in animation? |
+| 6      | 2?   | ??? |
+| 8      | 12?  | ??? - unset in this case |
 
 The remaining 78-byte chunk is impenetrable so far, but we should now have the
 information we need to display all the animated sequences in `WarHammer.ani`!
+
+How do we know it needs to be 78 bytes? One option is multiplying the final
+field of the type 2 record by 6. Maybe we have 6 bytes of description per frame,
+or maybe it's unrelated to frames?

internal/idx/idx.go

@@ -1,39 +1,58 @@
-// package idx parses the Idx/WarHammer.idx file.
-//
-// No, I don't know what it's for yet.
+// package idx parses the Idx/WarHammer.idx file. It groups the sprites in
+// Anim/WarHammer.ani into playable animations.
 package idx
 
 import (
 	"encoding/binary"
-	//"fmt"
-	"log"
+	"fmt"
+	//"log"
 	"os"
 	//"strings"
 )
 
-type Type1Record struct {
-	Offset1  uint32 // Where the type2 for this type1 is to be found
-	Unknown1 uint32 // ???
-	Offset2  uint32 // Another offset? But what to?
-}
-
-type Type2Record struct {
-	Unknown1 [4]byte // ???
-	Offset   uint32  // Where the type3 for this type2 is to be found
-	Unknown2 [4]byte // ??
-}
-
-type Type3Record struct {
-	First20 [20]byte
-	Last78  [78]byte
-}
+const (
+	NumGroups = 512 // Experimentally determined
+)
 
 type Idx struct {
 	Filename string
+	Groups   []Group
+}
 
-	Type1Records [512]Type1Record // Experimentally, there seem to be 512 of these
-	Type2Records []Type2Record
-	Type3Records []Type3Record
+type Group struct {
+	Spec    Spec
+	Records []Record
+	Details []Detail // Records and details are correlated by index
+}
+
+// type Spec links a set of animations to a starting sprite in WarHammer.ani
+type Spec struct {
+	Offset    uint32 // Where the Records for this Spec are to be found
+	Count     uint32 // Number of Records for this Spec
+	SpriteIdx uint32 // Index of the first sprite in
+}
+
+type Record struct {
+	// A guess, but each group of 8 records with increasing compass points share
+	// this value.
+	ActionID uint16
+
+	Compass byte // It's odd to only have one byte. Maybe Unknown1 belongs to this too?
+
+	Unknown1  byte   // ??? Only see values 0x33 and 0x00 for librarian.
+	Offset    uint32 // Where the Detail for this Record is to be found.
+	NumFrames uint32 // A guess, but seems to fit. Number of frames for this action + compass.
+}
+
+type Detail struct {
+	FirstSprite uint16 // Relative offset from the group's SpriteIdx
+	LastSprite  uint16 // Relative offset from the group's SpriteIdx
+	Unknown1    uint16 // Could also be LastSprite? Something else? AtRestSprite?
+	Unknown2    uint16 // Number of resting sprites, if we're AtRestSprite?
+
+	Padding [12]byte // Set to zero in the cases I've looked at so far.
+
+	// Remainder []byte // FIXME: no idea what this is yet, but we seem to have NumFrames*6 of them
 }
 
 func Load(filename string) (*Idx, error) {
@@ -44,29 +63,46 @@ func Load(filename string) (*Idx, error) {
 
 	defer f.Close()
 
-	out := &Idx{Filename: filename}
-
-	if err := binary.Read(f, binary.LittleEndian, &out.Type1Records); err != nil {
-		return nil, err
+	out := &Idx{
+		Filename: filename,
+		Groups:   make([]Group, NumGroups),
 	}
 
-	for i, rec := range out.Type1Records {
-		var off1diff uint32
-		var off2diff uint32
+	var specs [NumGroups]Spec
 
-		if i > 0 && rec.Offset1 > 0 {
-			lastRec := out.Type1Records[i-1]
-			off1diff = rec.Offset1 - lastRec.Offset1
-			off2diff = rec.Offset2 - lastRec.Offset2
+	if err := binary.Read(f, binary.LittleEndian, &specs); err != nil {
+		return nil, fmt.Errorf("reading specs: %v", err)
+	}
+
+	for i, spec := range specs {
+		group := &out.Groups[i]
+		group.Spec = spec
+		group.Records = make([]Record, spec.Count)
+		group.Details = make([]Detail, spec.Count)
+
+		if _, err := f.Seek(int64(spec.Offset), 0); err != nil {
+			return nil, fmt.Errorf("spec %v: seeking: %v", i, err)
 		}
 
-		log.Printf(
-			"%.3d: 0x%.6x diff=%.6d %.4d 0x%.6x diff=%.6d",
-			i, rec.Offset1, off1diff, rec.Unknown1, rec.Offset2, off2diff,
-			//			i,
-			//			rec.Unknown1[0], rec.Unknown1[1], rec.Unknown1[2], rec.Unknown1[3],
-			//			rec.Unknown1[4], rec.Unknown1[5], rec.Unknown1[6], rec.Unknown1[7],
-		)
+		// We can read all records at once
+		if err := binary.Read(f, binary.LittleEndian, &group.Records); err != nil {
+			return nil, fmt.Errorf("spec %v: reading records: %v", i, err)
+		}
+
+		// But we need to step through the records to learn where to read details
+		for j, rec := range group.Records {
+			// group.Details[j].Remainder = make([]byte, rec.NumFrames*6)
+
+			if _, err := f.Seek(int64(rec.Offset), 0); err != nil {
+				return nil, fmt.Errorf("spec %v, record %v: seeking to detail: %v", i, j, err)
+			}
+
+			if err := binary.Read(f, binary.LittleEndian, &group.Details[j]); err != nil {
+				return nil, fmt.Errorf("spec %v, record %v: reading detail: %v", i, j, err)
+			}
+		}
+
+		out.Groups[i] = *group
 	}
 
 	return out, nil