; ==============================================================================
; EBLAN ENGINE - Texture Management & Procedural Texture Generator
; ==============================================================================

.code

; ------------------------------------------------------------------------------
; GenerateDefaultTextures: Procedurally creates 128x128 32-bit BGRA textures
; Zero external asset dependency - works out of the box on any machine!
; ------------------------------------------------------------------------------
GenerateDefaultTextures PROC uses ebx ecx edx esi edi
    LOCAL texBase:DWORD, px:DWORD, py:DWORD, color:DWORD

    ; --------------------------------------------------------------------------
    ; Texture 1: Red Brick Wall
    ; --------------------------------------------------------------------------
    mov eax, OFFSET textureBuffer
    add eax, 1 * TEX_SIZE_BYTES
    mov texBase, eax

    mov py, 0
brick_y_loop:
    mov px, 0
brick_x_loop:
    ; Base brick color (Dark red/brown)
    mov color, 00852215h

    ; Mortar lines horizontally every 16 pixels
    mov eax, py
    and eax, 15
    cmp eax, 0
    je set_mortar
    cmp eax, 1
    je set_mortar

    ; Vertical mortar stagger: alternate every 16 rows
    mov edx, px
    mov eax, py
    and eax, 16
    jz @F
    add edx, 16                 ; shift vertical joint by 16 px on odd rows
@@:
    and edx, 31
    cmp edx, 0
    je set_mortar
    cmp edx, 1
    je set_mortar
    jmp apply_brick_noise

set_mortar:
    mov color, 00555555h        ; Gray mortar
    jmp write_brick_pixel

apply_brick_noise:
    ; Add subtle shade variation
    mov eax, px
    xor eax, py
    and eax, 7
    shl eax, 2
    add color, eax

write_brick_pixel:
    ; Write BGRA pixel to texture
    mov eax, py
    shl eax, 7                  ; py * 128
    add eax, px
    shl eax, 2                  ; * 4 bytes
    mov edi, texBase
    add edi, eax
    mov edx, color
    mov [edi], edx

    inc px
    cmp px, TEX_W
    jl brick_x_loop

    inc py
    cmp py, TEX_H
    jl brick_y_loop

    ; --------------------------------------------------------------------------
    ; Texture 2: Wood Planks
    ; --------------------------------------------------------------------------
    mov eax, OFFSET textureBuffer
    add eax, 2 * TEX_SIZE_BYTES
    mov texBase, eax

    mov py, 0
wood_y_loop:
    mov px, 0
wood_x_loop:
    ; Base wood color (Warm brown)
    mov color, 00683A12h

    ; Plank seams every 32 horizontal pixels
    mov eax, px
    and eax, 31
    cmp eax, 0
    jne @F
    mov color, 00201005h        ; Dark seam
    jmp write_wood_pixel
@@:
    ; Subtle wood grain variation based on py
    mov eax, py
    and eax, 3
    shl eax, 3
    add color, eax

write_wood_pixel:
    mov eax, py
    shl eax, 7
    add eax, px
    shl eax, 2
    mov edi, texBase
    add edi, eax
    mov edx, color
    mov [edi], edx

    inc px
    cmp px, TEX_W
    jl wood_x_loop

    inc py
    cmp py, TEX_H
    jl wood_y_loop

    ; --------------------------------------------------------------------------
    ; Texture 3: Stone / Cobblestone
    ; --------------------------------------------------------------------------
    mov eax, OFFSET textureBuffer
    add eax, 3 * TEX_SIZE_BYTES
    mov texBase, eax

    mov py, 0
stone_y_loop:
    mov px, 0
stone_x_loop:
    ; Base gray
    mov color, 00555555h

    ; Stone border grid (32x32 blocks)
    mov eax, px
    and eax, 31
    test eax, eax
    jz set_stone_border
    mov eax, py
    and eax, 31
    test eax, eax
    jz set_stone_border

    ; Noise
    mov eax, px
    imul eax, 3
    add eax, py
    and eax, 15
    shl eax, 2
    add color, eax
    jmp write_stone_pixel

set_stone_border:
    mov color, 00222222h

write_stone_pixel:
    mov eax, py
    shl eax, 7
    add eax, px
    shl eax, 2
    mov edi, texBase
    add edi, eax
    mov edx, color
    mov [edi], edx

    inc px
    cmp px, TEX_W
    jl stone_x_loop

    inc py
    cmp py, TEX_H
    jl stone_y_loop

    ; --------------------------------------------------------------------------
    ; Texture 4: Metal Tech / Rivets
    ; --------------------------------------------------------------------------
    mov eax, OFFSET textureBuffer
    add eax, 4 * TEX_SIZE_BYTES
    mov texBase, eax

    mov py, 0
metal_y_loop:
    mov px, 0
metal_x_loop:
    ; Base metal slate (blue-gray)
    mov color, 00606570h

    ; Rivets near corners (10, 10) and (118, 118)
    ; Check if within 4 pixels of a rivet center
    mov eax, px
    sub eax, 10
    imul eax, eax
    mov edx, py
    sub edx, 10
    imul edx, edx
    add eax, edx
    cmp eax, 16
    jle set_rivet

    mov eax, px
    sub eax, 118
    imul eax, eax
    mov edx, py
    sub edx, 118
    imul edx, edx
    add eax, edx
    cmp eax, 16
    jle set_rivet
    jmp write_metal_pixel

set_rivet:
    mov color, 00A0B0C0h        ; Shiny rivet highlight

write_metal_pixel:
    mov eax, py
    shl eax, 7
    add eax, px
    shl eax, 2
    mov edi, texBase
    add edi, eax
    mov edx, color
    mov [edi], edx

    inc px
    cmp px, TEX_W
    jl metal_x_loop

    inc py
    cmp py, TEX_H
    jl metal_y_loop

    ; --------------------------------------------------------------------------
    ; Texture 5: Door
    ; --------------------------------------------------------------------------
    mov eax, OFFSET textureBuffer
    add eax, 5 * TEX_SIZE_BYTES
    mov texBase, eax

    mov py, 0
door_y_loop:
    mov px, 0
door_x_loop:
    ; Door frame (outer 8 pixels)
    mov eax, px
    cmp eax, 8
    jl set_door_frame
    cmp eax, 120
    jge set_door_frame
    mov eax, py
    cmp eax, 8
    jl set_door_frame

    ; Door body (Deep wood)
    mov color, 00502D15h

    ; Brass door knob at (px=100, py=64)
    mov eax, px
    sub eax, 100
    imul eax, eax
    mov edx, py
    sub edx, 64
    imul edx, edx
    add eax, edx
    cmp eax, 36
    jle set_brass_knob
    jmp write_door_pixel

set_door_frame:
    mov color, 00333333h
    jmp write_door_pixel

set_brass_knob:
    mov color, 00FFD000h        ; Gold / Brass

write_door_pixel:
    mov eax, py
    shl eax, 7
    add eax, px
    shl eax, 2
    mov edi, texBase
    add edi, eax
    mov edx, color
    mov [edi], edx

    inc px
    cmp px, TEX_W
    jl door_x_loop

    inc py
    cmp py, TEX_H
    jl door_y_loop

    ; --------------------------------------------------------------------------
    ; Texture 7: Pillar / Marble Mosaic
    ; --------------------------------------------------------------------------
    mov eax, OFFSET textureBuffer
    add eax, 7 * TEX_SIZE_BYTES
    mov texBase, eax

    mov py, 0
pillar_y_loop:
    mov px, 0
pillar_x_loop:
    ; Vertical fluted pillar pattern
    mov eax, px
    and eax, 15
    cmp eax, 8
    jl set_pillar_light
    mov color, 00408090h        ; Dark turquoise
    jmp write_pillar_pixel

set_pillar_light:
    mov color, 0070B0C0h        ; Light turquoise

write_pillar_pixel:
    mov eax, py
    shl eax, 7
    add eax, px
    shl eax, 2
    mov edi, texBase
    add edi, eax
    mov edx, color
    mov [edi], edx

    inc px
    cmp px, TEX_W
    jl pillar_x_loop

    inc py
    cmp py, TEX_H
    jl pillar_y_loop

    ; --------------------------------------------------------------------------
    ; Texture 8: Glass (framed pane with diagonal shine)
    ; --------------------------------------------------------------------------
    mov eax, OFFSET textureBuffer
    add eax, 8 * TEX_SIZE_BYTES
    mov texBase, eax

    mov py, 0
glass_y_loop:
    mov px, 0
glass_x_loop:
    ; Base: dark blue-green tinted glass
    mov color, 00403020h

    ; Metal frame (outer 6 pixels)
    mov eax, px
    cmp eax, 6
    jl set_glass_frame
    cmp eax, 122
    jge set_glass_frame
    mov eax, py
    cmp eax, 6
    jl set_glass_frame
    cmp eax, 122
    jge set_glass_frame

    ; Diagonal shine streaks: (px + py) mod 64 in [0..3] or [24..27]
    mov eax, px
    add eax, py
    and eax, 63
    cmp eax, 4
    jl set_glass_shine
    cmp eax, 24
    jl write_glass_pixel
    cmp eax, 28
    jl set_glass_shine
    jmp write_glass_pixel

set_glass_frame:
    mov color, 00606060h        ; Steel frame
    jmp write_glass_pixel

set_glass_shine:
    mov color, 00907050h        ; Bright reflection streak

write_glass_pixel:
    mov eax, py
    shl eax, 7
    add eax, px
    shl eax, 2
    mov edi, texBase
    add edi, eax
    mov edx, color
    mov [edi], edx

    inc px
    cmp px, TEX_W
    jl glass_x_loop

    inc py
    cmp py, TEX_H
    jl glass_y_loop

    ; --------------------------------------------------------------------------
    ; Texture 9: Marble (cream slab with dark veins)
    ; --------------------------------------------------------------------------
    mov eax, OFFSET textureBuffer
    add eax, 9 * TEX_SIZE_BYTES
    mov texBase, eax

    mov py, 0
marble_y_loop:
    mov px, 0
marble_x_loop:
    ; Base: cream marble
    mov color, 00D8D0C0h

    ; Veins: wandering pseudo-noise lines
    mov eax, px
    imul eax, 7
    mov edx, py
    imul edx, 13
    add eax, edx
    mov edx, eax
    shr edx, 3
    add eax, edx
    and eax, 63
    cmp eax, 2
    jbe set_marble_vein
    cmp eax, 40
    jne marble_polish
    ; Single-pixel hairline vein
    jmp set_marble_vein

marble_polish:
    ; Subtle polish variation
    mov eax, px
    xor eax, py
    and eax, 3
    add color, eax
    jmp write_marble_pixel

set_marble_vein:
    mov color, 00555555h        ; Dark gray vein

write_marble_pixel:
    mov eax, py
    shl eax, 7
    add eax, px
    shl eax, 2
    mov edi, texBase
    add edi, eax
    mov edx, color
    mov [edi], edx

    inc px
    cmp px, TEX_W
    jl marble_x_loop

    inc py
    cmp py, TEX_H
    jl marble_y_loop

    ret
GenerateDefaultTextures ENDP

; ------------------------------------------------------------------------------
; LoadTexturePack: Optionally overrides procedural textures with
; assets/textures/texturepack.bin (see tools/make_texturepack.py).
; Layout: dd magic 'EBTX', dw version (1), dw slotCount,
;         then slotCount * 65536 bytes (128x128 BGRA per slot, slot 0 first).
; Returns: eax = 1 if pack loaded, 0 if procedural textures stay active.
; ------------------------------------------------------------------------------
LoadTexturePack PROC uses ebx ecx edx esi edi
    LOCAL hFile:DWORD
    LOCAL bytesRead:DWORD
    LOCAL magic:DWORD, pkVersion:DWORD, slotCount:DWORD

    invoke CreateFileA, OFFSET szTexPackPath, GENERIC_READ, FILE_SHARE_READ,\
           0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0
    mov hFile, eax
    cmp hFile, INVALID_HANDLE_VALUE
    je pack_fail

    ; Read 8-byte header (dd magic, dw version, dw slotCount)
    invoke ReadFile, hFile, ADDR magic, 4, ADDR bytesRead, 0
    test eax, eax
    jz pack_close_fail
    cmp bytesRead, 4
    jl pack_close_fail
    cmp magic, TEXPACK_MAGIC
    jne pack_close_fail

    invoke ReadFile, hFile, ADDR pkVersion, 2, ADDR bytesRead, 0
    cmp bytesRead, 2
    jl pack_close_fail
    cmp pkVersion, 1
    jne pack_close_fail

    invoke ReadFile, hFile, ADDR slotCount, 2, ADDR bytesRead, 0
    cmp bytesRead, 2
    jl pack_close_fail

    ; Clamp slot count to engine capacity
    mov eax, slotCount
    and eax, 0FFFFh
    cmp eax, MAX_TEXTURES
    jle @F
    mov eax, MAX_TEXTURES
@@:
    mov slotCount, eax
    test eax, eax
    jz pack_close_fail

    ; Read slotCount * TEX_SIZE_BYTES pixels straight into textureBuffer
    mov ecx, slotCount
    shl ecx, 16                 ; * 65536
    invoke ReadFile, hFile, OFFSET textureBuffer, ecx, ADDR bytesRead, 0
    test eax, eax
    jz pack_close_fail
    mov eax, slotCount
    shl eax, 16
    cmp bytesRead, eax
    jne pack_close_fail

    invoke CloseHandle, hFile
    mov texPackLoaded, 1
    mov eax, 1
    ret

pack_close_fail:
    invoke CloseHandle, hFile
pack_fail:
    xor eax, eax
    ret
LoadTexturePack ENDP