diff --git a/doc/file_hmp_spec.txt b/doc/file_hmp_spec.txt
index ac080db..e47a69f 100644
--- a/doc/file_hmp_spec.txt
+++ b/doc/file_hmp_spec.txt
@@ -1,21 +1,26 @@
-12B: zeros
-4B float: always 0x3f000000 (0.5)
-4B float: terrain height scale 
-4B float: always 0x3f000000
-2B int  : tile count
-2B int  : ?
-4B int  : offset to tiles
-4B int  : offset to some data?
-2B int  : width in BLK
-2B int  : height in BLK
-array[width * height] of 2B int: tile indices
-xB ?
-tiles
+HMP 
 {
-    2B int: texmap idx (from texture index file)
-    1B int: ?
-    1B uint: lo - minimum height in tile (probably for terrain LOD?)
-    1B uint: hi - maximum height in tile
-    array[25] of uint8: - 5x5 heights
+  12B: zeros
+  4B float: always 0x3f000000 (0.5)
+  4B float: terrain height scale 
+  4B float: always 0x3f000000
+  2B int  : tile count
+  2B int  : ?
+  4B int  : offset to tiles
+  4B int  : offset to some data?
+  2B int  : width in BLK
+  2B int  : height in BLK
+  array[width * height] of 2B int: tile indices 
+  xB ?
+  array[tile count] of TILE
+  2B 0x0000
 }
-2B 0x0000
+
+TILE [30B]
+{
+  2B int: texmap idx (from texture index file)
+  1B int: ?
+  1B int: lo - minimum height in tile (probably for terrain LOD? clipping?)
+  1B int: hi - maximum height in tile
+  array[25] of int8: 5x5 height values
+}
\ No newline at end of file
diff --git a/terrain_viewer/rs_world.pas b/terrain_viewer/rs_world.pas
index ab64263..b307f7a 100644
--- a/terrain_viewer/rs_world.pas
+++ b/terrain_viewer/rs_world.pas
@@ -20,9 +20,9 @@ type
   TTile = packed record
       texture_index: word;
       unknown_attrib: byte;
-      height_lo: byte;
-      height_hi: byte;
-      heights: array[0..24] of byte;
+      height_lo: shortint;
+      height_hi: shortint;
+      heights: array[0..24] of shortint;
   end;
   PTile = ^TTile;
 
@@ -37,12 +37,6 @@ type
       texture_index_map: array of integer;
   end;
 
-  TVertex3f = record
-      x, y, z: single;
-      u, v: single
-  end;
-  PVertex3f = ^TVertex3f;
-
   { TWorld }
 
   TWorld = class
@@ -55,7 +49,6 @@ type
 
     public
       heightmap: THeightmap;
-      vertex_array: PVertex3f;
       vertex_count: integer;
 
       property TileWidth: word read heightmap.width;
@@ -217,7 +210,7 @@ begin
   heightmap.blk := blk;
 
   //tiles
-  //writeln('tiles: ', tile_count);
+  //writeln('filepos: ', FilePos(f)); writeln('tile pos: ', tile_offset);
   Seek(f, tile_offset);
   heightmap.tile_count := tile_count;
   heightmap.tiles := getmem(tile_count * 30);
@@ -241,13 +234,11 @@ end;
 constructor TWorld.Create;
 begin
   height_texture := nil;
-  vertex_array := nil;
 end;
 
 destructor TWorld.Destroy;
 begin
   if height_texture <> nil then Freemem(height_texture);
-  if vertex_array <> nil then Freemem(vertex_array);
   inherited Destroy;
 end;
 
diff --git a/terrain_viewer/terrain_mesh.pas b/terrain_viewer/terrain_mesh.pas
index 675c9da..43af903 100644
--- a/terrain_viewer/terrain_mesh.pas
+++ b/terrain_viewer/terrain_mesh.pas
@@ -4,9 +4,9 @@ unit terrain_mesh;
 interface
 
 uses
-  Classes, SysUtils,
+  Classes, SysUtils, matrix,
   gl, glext, glu,
-  rs_world;
+  rs_world, vector_util;
 
 type
  TRenderOpts = record
@@ -17,17 +17,21 @@ type
       fg_to_draw: integer;
   end;
 
- TTerrainBlock = packed record
+ TTerrainBlock = record
      texture_index: integer;
-     vertices: array[0..25] of TVertex3f;
- end;
+     vertices: array[0..24] of Tvector3_single;         //25*3*4 = 300B
+     normals:  array[0..24] of Tvector3_single;         //25*3*4 = 300B
+ end; //~600B per block
 
   { TTerrainMesh }
   TTerrainMesh = class
     private
       terrain: TWorld;
       blocks: array of array of TTerrainBlock;
+      block_texcoords: array[0..24] of Tvector2_single;  //static, 25*2*4 = 200B
+      block_face_indices: array[0..16*2*3 - 1] of byte;  //static, 96B
       textures_glidx: array of integer;
+      procedure InitBlockStaticData;
       procedure TransformTiles;
     public
       destructor Destroy; override;
@@ -44,36 +48,60 @@ implementation
 }
 procedure TTerrainMesh.TransformTiles;
 
-  //basex/y - offset in vertices
-  //TODO solve flipped coords
-  procedure TileToBlock(var blk: TTerrainBlock; var tile: TTile; basex, basey: integer);
+  //basex/y - position in block units for given dimension (0..block_size-1)
+  //todo fix: the params are flipped.. and so are the calculations
+  function TileToBlock(var tile: TTile; basex, basey: integer): TTerrainBlock;
   const
     h_scale = 0.5;
   var
     x, y: integer;
-    v: TVertex3f;
-    width_half, height_half: integer;  //size in vertices
     v_scale: single;
   begin
-    width_half  := terrain.TileWidth  * 2;
-    height_half := terrain.TileHeight * 2;
+    result.texture_index := tile.texture_index;
+    //dim * vertices_per_tile - half_tile_dim * vertices_per_tile
+    basey := basey * 4 - terrain.TileHeight * 2;
+    basex := basex * 4 - terrain.TileWidth  * 2;
     v_scale := terrain.heightmap.y_scale;
     for y := 0 to 4 do
         for x := 0 to 4 do begin
-            v.x := (-width_half  + basex + x) * h_scale;
-            v.z := (-height_half + basey + y) * h_scale;
-            v.v := (1 - x/4);
-            v.u := y/4;
-            v.y := shortint(tile.heights[y+x*5]) * v_scale;
-            v.y := -v.y;
-
-            blk.vertices[y * 5 + x] := v;
+            result.vertices[y * 5 + x].init( //x,y,z
+              (basex + x) * h_scale,
+              tile.heights[y+x*5] * v_scale * -1,
+              (basey + y) * h_scale
+            );
+        end;
+  end;
+
+  //todo do proper per-vertex normal:
+  //this only calculates face normals and sets them to face's vertices, overwriting the value set
+  //from previous face
+  procedure FakeNormals(var blk: TTerrainBlock);
+    procedure SetTriData(const tri_idx: integer; const i0, i1, i2: byte);
+    var
+      normal: Tvector3_single;
+    begin
+      normal := GetNormal(blk.vertices[i0], blk.vertices[i1], blk.vertices[i2]);
+      blk.normals[i0] := normal;
+      blk.normals[i1] := normal;
+      blk.normals[i2] := normal;
+    end;
+  const
+    VertexStride = 5;
+  var
+    x, y, i, tri_idx: integer;
+  begin
+    tri_idx := 0;
+    for y := 0 to 3 do
+        for x := 0 to 3 do begin
+            i := y * VertexStride + x;
+            SetTriData(tri_idx, i+1, i, i+VertexStride);
+            SetTriData(tri_idx + 1, i+1, i+VertexStride, i+VertexStride+1);
+            tri_idx += 2;
         end;
-    blk.texture_index := tile.texture_index;
   end;
 
 var
-  x, y, i, tile_idx: integer;
+  x, y, tile_idx: integer;
   blk: TTerrainBlock;
   tile: TTile;
 begin
@@ -83,12 +111,46 @@ begin
           tile_idx := terrain.heightmap.blk[y * terrain.TileWidth + x];
           tile := terrain.heightmap.tiles[tile_idx];
 
-          TileToBlock(blk, tile, y * 4, x * 4);
+          blk := TileToBlock(tile, y, x);
+          FakeNormals(blk);
           blocks[y, x] := blk;
       end;
   end;
 end;
 
+{ InitBlockStaticData
+  Initializes data shared between tiles: face vertex indices, texture coords
+}
+procedure TTerrainMesh.InitBlockStaticData;
+
+  procedure SetTriData(const tri_idx: integer; const i0, i1, i2: byte);
+  begin
+    block_face_indices[tri_idx * 3 + 0] := i0;
+    block_face_indices[tri_idx * 3 + 1] := i1;
+    block_face_indices[tri_idx * 3 + 2] := i2;
+  end;
+
+const
+  VertexStride = 5;
+var
+  x, y, i, tri_idx: integer;
+begin
+  tri_idx := 0;
+  //init face indices
+  for y := 0 to 3 do
+      for x := 0 to 3 do begin
+          i := y * VertexStride + x;
+          SetTriData(tri_idx,   i+1, i, i+VertexStride);
+          SetTriData(tri_idx+1, i+1, i+VertexStride, i+VertexStride+1);
+          tri_idx += 2;
+      end;
+  //init uv coords
+  for y := 0 to 4 do
+      for x := 0 to 4 do begin
+          block_texcoords[y * 5 + x].init(y/4, 1 - x/4);  //u, v
+      end;
+end;
+
 destructor TTerrainMesh.Destroy;
 begin
   inherited Destroy;
@@ -100,6 +162,10 @@ begin
    terrain.LoadFromFiles('hmp_0', 'lv_0.text', 'lv_0.tex');
    //terrain.LoadFromFiles('hmp_1', 'lv_1.text', 'lv_1.tex');
    TransformTiles;
+   InitBlockStaticData;
+   WriteLn(Format('terrain size: %dx%d, tris: %d',
+                           [terrain.TileWidth, terrain.TileHeight,
+                           terrain.TileWidth * terrain.TileHeight * 4 * 4 * 2]));
 end;
 
 //generate textures. TODO texture atlas?
@@ -139,91 +205,42 @@ begin
 end;
 
 
-//cross product + normalize
-function GetNormalv(const v0, v1, v2: TVertex3f): TVertex3f;
-var
-  a, b: TVertex3f;
-  len: single;
-begin
-  a.x := v0.x - v1.x;
-  a.y := v0.y - v1.y;
-  a.z := v0.z - v1.z;
-
-  b.x := v1.x - v2.x;
-  b.y := v1.y - v2.y;
-  b.z := v1.z - v2.z;
-
-  result.x := (a.y * b.z) - (a.z * b.y);
-  result.y := (a.z * b.x) - (a.x * b.z);
-  result.z := (a.x * b.y) - (a.y * b.x);
-
-  len := sqrt( sqr(result.x) + sqr(result.y) + sqr(result.z) );
-  if len = 0 then len := 1;
-
-  result.x /= len;
-  result.y /= len;
-  result.z /= len;
-end;
-
-
 //draw vertices from each block
 procedure TTerrainMesh.DrawGL(opts: TRenderOpts);
-
-  procedure RenderBlock(var blk: TTerrainBlock);
-    procedure RenderTri(i0, i1, i2:integer);
-    var
-      v, n: TVertex3f;
-    begin
-      n := GetNormalv(blk.vertices[i0], blk.vertices[i1], blk.vertices[i2]);
-      v := blk.vertices[i0];
-      glNormal3f(n.x, n.y, n.z);
-      glTexCoord2f(v.u, v.v);
-      glVertex3fv(@v);
-      v := blk.vertices[i1];
-      glTexCoord2f(v.u, v.v);
-      glVertex3fv(@v);
-      v := blk.vertices[i2];
-      glTexCoord2f(v.u, v.v);
-      glVertex3fv(@v);
-    end;
-  var
-    i, x, y, stride: integer;
-  begin
-    stride := 5;
-    glBindTexture(GL_TEXTURE_2D, textures_glidx[blk.texture_index]);
-
-    glBegin(GL_TRIANGLES);
-    //glColor3f(0, 1, 0);
-    for y := 0 to 3 do
-        for x := 0 to 3 do begin
-            //do two triangles
-            i := y * stride + x;
-            RenderTri(i+1, i, i+stride);
-            RenderTri(i+1, i+stride, i+stride+1);
-        end;
-    glEnd;
-  { //only 2 tris per block
-    glBegin(GL_TRIANGLES);
-      i := y * stride + x;
-      RenderTri(0, 4, 24);
-      RenderTri(24, 20, 0);
-    glEnd;
-  }
-  end;
-
 var
   x, y: integer;
   blk: TTerrainBlock;
+  last_tex_index: integer;
 begin
   if opts.wireframe then
       glPolygonMode(GL_FRONT_AND_BACK, GL_LINE)
   else
       glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+
   glEnable(GL_TEXTURE_2D);
+  glEnableClientState(GL_VERTEX_ARRAY);
+  glEnableClientState(GL_NORMAL_ARRAY);
+  glEnableClientState(GL_TEXTURE_COORD_ARRAY);
+  last_tex_index := -1;
+
   for y := 0 to terrain.TileHeight - 1 do
       for x := 0 to terrain.TileWidth - 1 do begin
           blk := blocks[y, x];
-          RenderBlock(blk);
+          //repeated texture binding slows this down a lot (68->30fps)
+          //todo sort by texture?
+          if last_tex_index <> blk.texture_index then begin
+              last_tex_index := blk.texture_index;
+              glBindTexture(GL_TEXTURE_2D, textures_glidx[last_tex_index]);
+          end;
+
+          glVertexPointer(3, GL_FLOAT, sizeof(Tvector3_single), @blk.vertices[0].data[0]);
+          glNormalPointer(GL_FLOAT, sizeof(Tvector3_single), @blk.normals[0].data[0]);
+          glTexCoordPointer(2, GL_FLOAT, sizeof(Tvector2_single), @block_texcoords[0].data[0]);
+
+          if opts.points then
+              glDrawArrays(GL_POINTS, 0, 25)
+          else
+              glDrawElements(GL_TRIANGLES, 16*2*3, GL_UNSIGNED_BYTE, @block_face_indices);
       end;
 end;
 
diff --git a/terrain_viewer/terrain_viewer.lpi b/terrain_viewer/terrain_viewer.lpi
index d3029c3..f3e2adb 100644
--- a/terrain_viewer/terrain_viewer.lpi
+++ b/terrain_viewer/terrain_viewer.lpi
@@ -37,7 +37,7 @@
         <PackageName Value="LCL"/>
       </Item1>
     </RequiredPackages>
-    <Units Count="3">
+    <Units Count="4">
       <Unit0>
         <Filename Value="terrain_viewer.pas"/>
         <IsPartOfProject Value="True"/>
@@ -53,6 +53,11 @@
         <IsPartOfProject Value="True"/>
         <UnitName Value="rs_world"/>
       </Unit2>
+      <Unit3>
+        <Filename Value="vector_util.pas"/>
+        <IsPartOfProject Value="True"/>
+        <UnitName Value="vector_util"/>
+      </Unit3>
     </Units>
   </ProjectOptions>
   <CompilerOptions>
diff --git a/terrain_viewer/terrain_viewer.pas b/terrain_viewer/terrain_viewer.pas
index 59b7f81..49fcd43 100644
--- a/terrain_viewer/terrain_viewer.pas
+++ b/terrain_viewer/terrain_viewer.pas
@@ -22,7 +22,7 @@ program terrain_viewer;
 uses
   sysutils, math,
   gl, glu, glext, sdl,
-  terrain_mesh, rs_world;
+  terrain_mesh;
 
 const
   SCR_W_fscrn = 1024;
diff --git a/terrain_viewer/vector_util.pas b/terrain_viewer/vector_util.pas
new file mode 100644
index 0000000..7dff17e
--- /dev/null
+++ b/terrain_viewer/vector_util.pas
@@ -0,0 +1,33 @@
+unit vector_util;
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+  matrix;
+
+function GetNormal(v0, v1, v2: Tvector3_single): Tvector3_single;
+
+implementation
+
+//cross product + normalize
+function GetNormal(v0, v1, v2: Tvector3_single): Tvector3_single;
+var
+  a, b: Tvector3_single;
+  len: single;
+begin
+  a := v0 - v1;
+  b := v1 - v2;
+
+  result.data[0] := (a.data[1] * b.data[2]) - (a.data[2] * b.data[1]);
+  result.data[1] := (a.data[2] * b.data[0]) - (a.data[0] * b.data[2]);
+  result.data[2] := (a.data[0] * b.data[1]) - (a.data[1] * b.data[0]);
+
+  len := result.length;
+  if len = 0 then len := 1;
+
+  result /= len;
+end;
+
+end.
+