diff --git a/shader/chasm.vert b/shader/chasm.vert
new file mode 100644
index 000000000..e8e49bc67
--- /dev/null
+++ b/shader/chasm.vert
@@ -0,0 +1,6 @@
+#version 450 core
+layout (std140, binding = 0) uniform TheMat { mat4 theMat; } ;
+layout (std430, binding = 7) readonly buffer Pos { vec2 pos[]; };
+void main() {
+  gl_Position = theMat * vec4(pos[gl_VertexID],0,1);
+}
diff --git a/src/Data/Preload/Render.hs b/src/Data/Preload/Render.hs
index c4d04e07a..5ce271cbd 100644
--- a/src/Data/Preload/Render.hs
+++ b/src/Data/Preload/Render.hs
@@ -44,7 +44,7 @@ data RenderData = RenderData
     , _floorVBO :: VBO
     , _floorShader :: Shader
     , _chasmVBO :: VBO
-    , _chasmShader :: Shader
+    , _chasmShader :: GLuint
     , _winVBO :: VBO
     , _wallVBO :: VBO
     , _cloudVBO :: VBO
diff --git a/src/Dodge/Render.hs b/src/Dodge/Render.hs
index 4fb58ddc8..1224bc5c1 100644
--- a/src/Dodge/Render.hs
+++ b/src/Dodge/Render.hs
@@ -145,16 +145,12 @@ doDrawing' win pdata u = do
     glUseProgram fs
     glDrawArrays GL_TRIANGLES 0 (fromIntegral nIndices)
     -- draw chasm shader blocking floor
-    glUseProgram (pdata ^. chasmShader . shaderUINT)
-    glBindVertexArray $ pdata ^. chasmShader . shaderVAO . vaoName
+    glUseProgram (pdata ^. chasmShader)
     glDepthMask GL_FALSE
     glDrawBuffer GL_NONE
     glStencilOp GL_KEEP GL_KEEP GL_INCR
     with 0 $ glClearNamedFramebufferiv (pdata ^. fboBase . _1 . unFBO) GL_STENCIL 0
-    glDrawArrays
-        (_unPrimitiveMode $ pdata ^. chasmShader . shaderPrimitive)
-        0
-        (fromIntegral nchs)
+    glDrawArrays GL_TRIANGLES 0 (fromIntegral nchs)
     withArray [GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2] $
         glNamedFramebufferDrawBuffers (pdata ^. fboBase . _1 . unFBO) 3
     glDepthMask GL_TRUE
diff --git a/src/Dodge/WorldLoad.hs b/src/Dodge/WorldLoad.hs
index a858c1c3e..4449cf522 100644
--- a/src/Dodge/WorldLoad.hs
+++ b/src/Dodge/WorldLoad.hs
@@ -1,5 +1,7 @@
 module Dodge.WorldLoad (postUniverseLoadSideEffect) where
 
+import Shader.Parameters
+import Graphics.GL.Core45
 import Control.Lens
 import Control.Monad
 import Data.Preload.Render
@@ -16,8 +18,12 @@ postWorldLoad :: RenderData -> CWorld -> IO CWorld
 postWorldLoad rdata cw = do
     nfloorvxs <- foldM (pokeTile (rdata ^. floorVBO . vboPtr)) 0 (cw ^. cwTiles)
     bufferPokedVBO (rdata ^. floorVBO) nfloorvxs
-    nchasmvxs <- foldM (pokeChasm (rdata ^. chasmVBO . vboPtr)) 0 (cw ^. chasms)
-    bufferPokedVBO (rdata ^. chasmVBO) nchasmvxs
+    let chbo = rdata ^. chasmVBO . vboName
+        chptr = rdata ^. chasmVBO . vboPtr
+    nchasmvxs <- foldM (pokeChasm chptr) 0 (cw ^. chasms)
+    glInvalidateBufferData chbo
+    glNamedBufferStorage chbo (fromIntegral $ 2 * nchasmvxs * floatSize) chptr 0
+    glBindBufferBase GL_SHADER_STORAGE_BUFFER 7 chbo
     return $
         cw & numberFloorVerxs .~ nfloorvxs
             & numberChasmVerxs .~ nchasmvxs
diff --git a/src/Preload/Render.hs b/src/Preload/Render.hs
index d5d6e1132..cbac82c0f 100644
--- a/src/Preload/Render.hs
+++ b/src/Preload/Render.hs
@@ -137,15 +137,10 @@ preloadRender = do
     initTexture2DArraySquare 41 3 GL_LINEAR_MIPMAP_LINEAR GL_LINEAR "data/normalMaps/normalArray.png"
 
     putStrLn "Setup chasm VBO, shader"
-    let chasmverxstrd = 3
-    chasmvbo <- setupVBOStatic (floatSize * chasmverxstrd)
-    chasmshader <-
-        makeShaderUsingVBO
-            "positional/blank"
-            [vert, frag]
-            (toFloatVAs [3])
-            pmTriangles
-            chasmvbo
+    chvbo <- mglCreate glCreateBuffers
+    chptr <- mallocArray (2 * 65536)
+    let chasmvbo = VBO chvbo chptr floatSize
+    chasmshader <- makeSourcedShader "chasm" [vert]
     framebuf2 <- newTextureFramebuffer
     framebuf3 <- newTextureFramebuffer
 
diff --git a/src/Shader/Poke/Floor.hs b/src/Shader/Poke/Floor.hs
index 7251b0188..583430051 100644
--- a/src/Shader/Poke/Floor.hs
+++ b/src/Shader/Poke/Floor.hs
@@ -3,6 +3,7 @@ module Shader.Poke.Floor (
     pokeChasm,
 ) where
 
+import Shader.Parameters
 import Control.Monad
 import Data.Tile
 import Foreign
@@ -22,10 +23,9 @@ pokeTileVerx tangent tilez ptr i (V2 x y, V2 s t) = do
     return $ i + 1
 
 pokeChasm :: Ptr Float -> Int -> [Point2] -> IO Int
-pokeChasm ptr i ps =
-    foldM (pokeChasmVerx ptr) i $ polyToTris ps
+pokeChasm ptr i ps = foldM (pokeChasmVerx ptr) i $ polyToTris ps
 
 pokeChasmVerx :: Ptr Float -> Int -> Point2 -> IO Int
-pokeChasmVerx ptr i (V2 x y) = do
-    zipWithM_ (\off -> pokeElemOff ptr (i * 3 + off)) [0 ..] [x, y, 0]
+pokeChasmVerx ptr i p = do
+    pokeByteOff ptr (floatSize*i*2) p
     return $ i + 1