Draw to fullscreen using one triangle

src/Dodge/Render.hs

@@ -174,7 +174,8 @@ doDrawing' win pdata u = do
     glEnable GL_BLEND
     glBlendFunc GL_ZERO GL_ONE_MINUS_SRC_COLOR
     glUseProgram (pdata ^. fullscreenShader)
-    glDrawArrays GL_TRIANGLES 0 6
+    --glDrawArrays GL_TRIANGLES 0 6
+    glDrawArrays GL_TRIANGLES 0 3
     -- no longer need lighting texture
     with GL_COLOR_ATTACHMENT0 $
         glInvalidateNamedFramebufferData (pdata ^. fboLighting . _1 . unFBO) 1
@@ -217,7 +218,8 @@ doDrawing' win pdata u = do
     --        glClearNamedFramebufferfv (pdata ^. fboHalf2 . _1 . unFBO) GL_COLOR 0
     --    glBlendFunc GL_ONE GL_ONE_MINUS_SRC_ALPHA
     glUseProgram (_bloomBlurShader pdata)
-    glDrawArrays GL_TRIANGLES 0 6
+    --glDrawArrays GL_TRIANGLES 0 6
+    glDrawArrays GL_TRIANGLES 0 3
     when (cfig ^. gr_bloom) $ do
         replicateM_ 1 $
             pingPongBetween
@@ -270,7 +272,8 @@ doDrawing' win pdata u = do
         glBindTextureUnit 0 (pdata ^. fboCloud . _2 . _2 . unTO)
         glDepthMask GL_FALSE
         glUseProgram (pdata ^. alphaDivideShader)
-        glDrawArrays GL_TRIANGLES 0 6
+        --glDrawArrays GL_TRIANGLES 0 6
+        glDrawArrays GL_TRIANGLES 0 3
         ----draw lightmap for cloud buffer
         glDepthMask GL_TRUE
         glDepthFunc GL_LESS
@@ -327,20 +330,24 @@ doDrawing' win pdata u = do
     glEnable GL_BLEND
     glBlendFuncSeparate GL_ZERO GL_ONE_MINUS_SRC_COLOR GL_ZERO GL_ONE
     glUseProgram (pdata ^. fullscreenShader)
-    glDrawArrays GL_TRIANGLES 0 6
+    --glDrawArrays GL_TRIANGLES 0 6
+    glDrawArrays GL_TRIANGLES 0 3
     glBlendFunc GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA
     -- bind base buffer for drawing clouds and bloom
     glBindFramebuffer GL_FRAMEBUFFER (pdata ^. fboBase . _1 . unFBO)
     glUseProgram (pdata ^. fullscreenShader)
     glBindTextureUnit 0 (pdata ^. fboWindow . _2 . _2 . unTO)
     glBlendFunc GL_DST_COLOR GL_ONE_MINUS_SRC_ALPHA
-    glDrawArrays GL_TRIANGLES 0 6
+    --glDrawArrays GL_TRIANGLES 0 6
+    glDrawArrays GL_TRIANGLES 0 3
     glBindTextureUnit 0 (pdata ^. fboCloud . _2 . _1 . unTO)
     glBlendFunc GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA
-    glDrawArrays GL_TRIANGLES 0 6
+    --glDrawArrays GL_TRIANGLES 0 6
+    glDrawArrays GL_TRIANGLES 0 3
     glBindTextureUnit 0 (pdata ^. fboWindow . _2 . _1 . unTO)
     glBlendFunc GL_DST_COLOR GL_ONE_MINUS_SRC_ALPHA
-    glDrawArrays GL_TRIANGLES 0 6
+    --glDrawArrays GL_TRIANGLES 0 6
+    glDrawArrays GL_TRIANGLES 0 3
 
     --Draw blurred bloom onto base buffer
     glEnable GL_BLEND
@@ -348,7 +355,8 @@ doDrawing' win pdata u = do
     --glBlendFunc GL_ONE GL_ONE
     glBindTextureUnit 0 (_unTO . snd $ _fboHalf1 pdata)
     glUseProgram (pdata ^. fullscreenShader)
-    glDrawArrays GL_TRIANGLES 0 6
+    --glDrawArrays GL_TRIANGLES 0 6
+    glDrawArrays GL_TRIANGLES 0 3
 
     --set viewport for radial distortion
     --setViewportSize (round winx) (round winy)
@@ -361,7 +369,8 @@ doDrawing' win pdata u = do
             glBindTextureUnit 0 $ pdata ^. fboBase . _2 . _1 . unTO
             glBindFramebuffer GL_FRAMEBUFFER 0
             glUseProgram (pdata ^. fullscreenShader)
-            glDrawArrays GL_TRIANGLES 0 6
+            --glDrawArrays GL_TRIANGLES 0 6
+            glDrawArrays GL_TRIANGLES 0 3
         rs' -> do
             let rs = take 15 rs'
             glBindFramebuffer GL_FRAMEBUFFER 0
@@ -371,7 +380,8 @@ doDrawing' win pdata u = do
             glBindTextureUnit 1 $ pdata ^. fboBase . _2 . _1 . unTO
             glUseProgram (pdata ^. barrelShader . _1)
             glUniform1i 0 (fromIntegral (length rs))
-            glDrawArrays GL_TRIANGLES 0 6
+            --glDrawArrays GL_TRIANGLES 0 6
+            glDrawArrays GL_TRIANGLES 0 3
     glBlendFunc GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA
     -- draw the overlay
     glDepthFunc GL_ALWAYS

src/Preload/Render.hs

@@ -42,7 +42,8 @@ preloadRender = do
     glBindBufferBase GL_UNIFORM_BUFFER 1 lightubo
 
     fulltexbo <- mglCreate glCreateBuffers
-    let ftsize = fromIntegral $ sizeOf (0::Float) * 6 * 4
+    --let ftsize = fromIntegral $ sizeOf (0::Float) * 6 * 4
+    let ftsize = fromIntegral $ sizeOf (0::Float) * 3 * 4
     withArray cornerList $ \ptr ->
         glNamedBufferStorage fulltexbo ftsize ptr 0
     glBindBufferBase GL_UNIFORM_BUFFER 2 fulltexbo
@@ -226,6 +227,15 @@ preloadRender = do
 --------------------end preloadRender
 cornerList :: [Float]
 cornerList = concat
+    [ bl, br, tl
+    ]
+  where
+    bl = [-1, -1, 0, 0]
+    br = [ 3, -1, 2, 0]
+    tl = [-1,  3, 0, 2]
+
+cornerList' :: [Float]
+cornerList' = concat
     [ bl, br, tl
     , tl, br, tr
     ]