diff --git a/.ccls b/.ccls
index 45eebca..5f14576 100644
--- a/.ccls
+++ b/.ccls
@@ -4,3 +4,4 @@ gcc
 -Isrc/ecs/headers
 -Isrc/ecs/components/headers
 -Icore/src/headers
+-Iassets/asset_builder/src/headers
diff --git a/assets/asset_builder/README.md b/assets/asset_builder/README.md
new file mode 100644
index 0000000..832e61c
--- /dev/null
+++ b/assets/asset_builder/README.md
@@ -0,0 +1,11 @@
+# Asset file structure
+
+|    Description    |               Length                |
+| :---------------- | :---------------------------------- |
+| Assets number     | int (32 bits)                       |
+| ...               |                                     |
+| Asset name        | const char * (variable length)      |
+| Asset start index | int (32 bits)                       |
+| Asset end index   | int (32 bits)                       |
+| ...               |                                     |
+| Asset data        | depend on assets content and number |
\ No newline at end of file
diff --git a/assets/asset_builder/src/Makefile b/assets/asset_builder/src/Makefile
index 8fb3ea6..5b74064 100644
--- a/assets/asset_builder/src/Makefile
+++ b/assets/asset_builder/src/Makefile
@@ -1,11 +1,12 @@
 # Source files
 ASSET_BUILDER_SOURCES := \
-  main.c
+  main.c \
+  asset_file.c
 
 # Compiler and flags
 ASSET_BUILDER_CC = gcc
 #ASSET_BUILDER_CFLAGS = -std=c17 -pedantic -O3 # RELEASE
-ASSET_BUILDER_CFLAGS = -std=c17 --pedantic -O0 -g \
+ASSET_BUILDER_CFLAGS = -std=c17 --pedantic -O0 -g $(shell pkg-config --cflags libpng) \
 	-Wall -Wno-missing-braces -Wextra -Wno-missing-field-initializers \
     -Wformat=2 -Wswitch-default -Wswitch-enum -Wcast-align \
     -Wpointer-arith -Wbad-function-cast -Wstrict-overflow=5 \
@@ -15,7 +16,7 @@ ASSET_BUILDER_CFLAGS = -std=c17 --pedantic -O0 -g \
     -Wold-style-definition # DEVELOPEMENT
 
 ASSET_BUILDER_INCLUDE_DIRS = $(ASSET_BUILDER_DIR)/headers
-ASSET_BUILDER_LDFLAGS =
+ASSET_BUILDER_LDFLAGS = $(shell pkg-config --libs libpng)
 
 # Deduce objects
 ASSET_BUILDER_OBJECTS = $(ASSET_BUILDER_SOURCES:%.c=$(BUILD_DIR)/$(ASSET_BUILDER_DIR)/%.o)
@@ -24,7 +25,7 @@ ASSET_BUILDER_OBJECTS = $(ASSET_BUILDER_SOURCES:%.c=$(BUILD_DIR)/$(ASSET_BUILDER
 CURRENT_ASSET_BUILDER_FILE := 0
 
 # Build asset builder target
-build_asset_builder: asset_builder_setup count_asset_builder_build $(BUILD_DIR)/$(ASSET_BUILDER_DIR)/$(ASSET_BUILDER_OUTPUT) asset_builder_end
+build_asset_builder: asset_builder_setup count_asset_builder_build asset_builder_end
 
 # Source build directories
 asset_builder_setup:
@@ -48,7 +49,7 @@ $(BUILD_DIR)/$(ASSET_BUILDER_DIR)/%.o: $(ASSET_BUILDER_DIR)/%.c
 	$(Q)$(SRC_CC) $(SRC_CFLAGS) $(ASSET_BUILDER_INCLUDE_DIRS:%=-I%) -MMD -MP -c $< -o $@
 
 # Print ending message
-asset_builder_end:
+asset_builder_end: $(BUILD_DIR)/$(ASSET_BUILDER_DIR)/$(ASSET_BUILDER_OUTPUT)
 	@echo "Built target $(ASSET_BUILDER_OUTPUT)"
 
 # Source files dependencies
diff --git a/assets/asset_builder/src/asset_file.c b/assets/asset_builder/src/asset_file.c
new file mode 100644
index 0000000..038a3a1
--- /dev/null
+++ b/assets/asset_builder/src/asset_file.c
@@ -0,0 +1,81 @@
+#include "asset_file.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <png.h>
+
+int parse_png_for_header(const char *file_name, asset_def_t *asset_def);
+
+int parse_file_for_header(const char *file_name, asset_def_t *asset_def)
+{
+    const char *file_name_dot = strrchr(file_name, '.');
+
+    if(!file_name_dot)
+    {
+        return -1;  // no extension
+    }
+
+    const char *file_name_ext = file_name_dot + 1;
+
+    if(!strcmp(file_name_ext, "png"))
+    {
+        return parse_png_for_header(file_name, asset_def);
+    }
+    else
+    {
+        return -2;  // extension not supported
+    }
+
+    return 0;
+}
+
+int parse_png_for_header(const char *file_name, asset_def_t *asset_def)
+{
+    FILE *input_png_file = fopen(file_name, "rb");
+
+    if(!input_png_file)
+    {
+        fclose(input_png_file);
+        return -3;
+    }
+
+    fclose(input_png_file);
+
+    return 0;
+
+    // Check png autenticity.
+    unsigned char sig[8];
+    fread(sig, 1, 8, input_png_file);
+    if(!png_check_sig(sig, 8))
+    {
+        fclose(input_png_file);
+        return -4;   // bad signature
+    }
+
+    // PNG structs
+    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+    if(!png_ptr)
+    {
+        fclose(input_png_file);
+        return -5;   // out of memory
+    }
+
+    png_infop info_ptr = png_create_info_struct(png_ptr);
+    if(!info_ptr)
+    {
+        png_destroy_read_struct(&png_ptr, NULL, NULL);
+        fclose(input_png_file);
+        return -5;   // out of memory
+    }
+
+    // Fill structs and load data
+    png_init_io(png_ptr, input_png_file);
+    png_set_sig_bytes(png_ptr, 8);
+    png_read_info(png_ptr, info_ptr);
+
+    printf("%s bit depth : %d", file_name, png_get_bit_depth(png_ptr, info_ptr));
+
+    fclose(input_png_file);
+
+    return 0;
+}
diff --git a/assets/asset_builder/src/headers/asset_file.h b/assets/asset_builder/src/headers/asset_file.h
new file mode 100644
index 0000000..11e6080
--- /dev/null
+++ b/assets/asset_builder/src/headers/asset_file.h
@@ -0,0 +1,18 @@
+#ifndef ASSET_FILE_H
+#define ASSET_FILE_H
+
+#include <stdint.h>
+
+typedef struct asset_def_t {
+    const char *name;
+    uint32_t start, end;
+} asset_def_t;
+
+typedef struct asset_file_header_t {
+    uint32_t assets_number;
+    asset_def_t *assets_def;
+} asset_file_header_t;
+
+int parse_file_for_header(const char *file_name, asset_def_t *asset_def);
+
+#endif // ASSET_FILE_H
\ No newline at end of file
diff --git a/assets/asset_builder/src/main.c b/assets/asset_builder/src/main.c
index 635b841..8895d0b 100644
--- a/assets/asset_builder/src/main.c
+++ b/assets/asset_builder/src/main.c
@@ -1,11 +1,68 @@
 #include <stdio.h>
 
+#include "asset_file.h"
+
+void print_error(const char *content)
+{
+    printf("\033[31merror\033[m: %s\n", content);
+}
+
 int main(int argc, char *argv[])
 {
+    // Verify arguments minimum number.
     printf("%d args\n", argc);
 
-    for(int i = 0; i < argc; i++)
+    if(argc < 3)
+    {
+        print_error("not enough args.");
+        return -1;
+    }
+
+    for(size_t i = 0; i < (size_t)argc; i++)
         puts(argv[i]);
 
+    // Create and open output file.
+    FILE *output_asset = fopen(argv[2], "wb");
+
+    if(!output_asset)
+    {
+        print_error("could not create output file.");
+        return -1;
+    }
+
+    // Parse input files to create header structure.
+    asset_file_header_t asset_file_header;
+
+    asset_file_header.assets_number = argc - 2;
+
+    for(size_t i = 2; i < (size_t)argc; i++)
+    {
+        asset_def_t asset_def;
+        int ret = parse_file_for_header(argv[i], &asset_def);
+        if(ret)
+        {
+            puts(argv[i]);
+
+            switch(ret)
+            {
+              case -1:
+                print_error("file does not have an extension.");
+                return -1;
+              case -2:
+                print_error("extension not yet supported.");
+                return -1;
+              case -3:
+                print_error("failed to open file.");
+                return -1;
+              case -4:
+                print_error("file not valid.");
+                return -1;
+              case -5:
+                print_error("memory allocation failed.");
+                return -1;
+            }
+        }
+    }
+
     return 0;
 }
diff --git a/shell.nix b/shell.nix
index 2a4c63b..8e34b9b 100644
--- a/shell.nix
+++ b/shell.nix
@@ -9,9 +9,10 @@ stdenv.mkDerivation {
   buildInputs = [
     SDL2
     SDL2_image
+    libpng
   ];
-  shellHook = ''
-    export LD_LIBRARY_PATH=${pkgs.SDL2}/lib:${pkgs.SDL2_image}/lib:$LD_LIBRARY_PATH
-    export PKG_CONFIG_PATH=${pkgs.SDL2}/lib/pkgconfig:${pkgs.SDL2_image}/lib/pkgconfig:$PKG_CONFIG_PATH
-  '';
+#  shellHook = ''
+#    export LD_LIBRARY_PATH=${pkgs.SDL2}/lib:${pkgs.SDL2_image}/lib:$LD_LIBRARY_PATH
+#    export PKG_CONFIG_PATH=${pkgs.SDL2}/lib/pkgconfig:${pkgs.SDL2_image}/lib/pkgconfig:$PKG_CONFIG_PATH
+#  '';
 }