Start implementing ceiling stencil shader

shader/lighting/wallShadow.geom

@@ -19,11 +19,29 @@ vec2 closestPointOnSeg (vec2 a,vec2 b, vec2 p) {
   }
 }
 // End include 2023-03-13 15:33:44.438312149 UTC
+vec2 closestPointOnLine (vec2 a,vec2 b, vec2 p) {
+  float x = closestPointOnLineParam(a,b,p);
+      return a + (x * (b- a));
+}
+vec2 invclosestPointOnLine (vec2 a,vec2 b, vec2 p) {
+  float x = dot (p-a,p-a)/ dot(p-a,b-a);
+      return a + x*(b- a);
+}
 vec2 shift(vec2 p) {
   return vec2(lightPos.xy + (rad * normalize(p - lightPos.xy)));
 }
-float isLHS(vec2 startV, vec2 testV) {
+float detV(vec2 p, vec2 q) {
-  return sign(-startV.x * testV.y + startV.y * testV.x);
+    return p.x*q.y - p.y*q.x;
+}
+float isLHS(vec2 p, vec2 q) {
+  return sign(-detV(p,q));
+}
+// the following does NOT check for division by zero: do not reuse this unless
+// you are certain this cannot happen
+vec2 intersectLL(vec2 p1,vec2 p2,vec2 q1,vec2 q2){
+    float den = detV (p1-p2,q1-q2);
+    float t = detV (p1-q1,q1-q2);
+    return p1 + (t/den)*(p2-p1);
 }
 // constructs a "bridge" shape
 void main() {
@@ -31,21 +49,36 @@ void main() {
   vec2 p2 = gl_in[0].gl_Position.zw;
   vec2 closepoint = closestPointOnSeg(p1,p2,lightPos.xy);
   if (isLHS(p1 - lightPos.xy, p2 - lightPos.xy) < 0 && distance(closepoint,lightPos.xy) < rad) {
-      // this is a point far along the ray from the light source to the midpoint
+    vec2 xxxy = p1 + (0.25 * (p2 -p1));
-      // of the wall. Necessary in case the light source is very close to the
+    vec2 xt = shift(xxxy);
-      // wall
+    vec2 xo = invclosestPointOnLine(lightPos.xy,p1,xt);
+    vec2 xyyy = p1 + (0.75 * (p2 -p1));
+    vec2 yt = shift(xyyy);
+    vec2 yo = invclosestPointOnLine(lightPos.xy,p2,yt);
+
+    vec2 xoo = (distance(xo, lightPos.xy) < distance(p1, lightPos.xy)
+                || distance(p1,lightPos.xy)>rad
+                    ?  p1 : xo);
+    vec2 yoo = (distance(yo, lightPos.xy) < distance(p2, lightPos.xy) 
+                || distance(p2,lightPos.xy)>rad 
+                ?  p2 : yo);
+
+    vec2 mo = intersectLL(xoo,xt,yoo,yt);
+
     vec2 closeshift = (rad * normalize(closepoint - lightPos.xy)) + lightPos.xy - closepoint;
     vec2 shifto = (rad * normalize(closepoint - lightPos.xy)) + closepoint;
-    vec2 p1cs = p1 + closeshift;
+    //vec2 p1o = vec2( distance(p1,lightPos.xy) > rad ? p1 : shift(p1) );
-    vec2 p1o = vec2( distance(p1,lightPos.xy) > rad ? p1cs : shift(p1) );
+    vec2 p1o = xoo;
-    vec2 p2cs = p2 + closeshift;
+    //vec2 p2o = vec2( distance(p2,lightPos.xy) > rad ? p2 : shift(p2) );
-    vec2 p2o = vec2( distance(p2,lightPos.xy) > rad ? p2cs : shift(p2) );
+    vec2 p2o = yoo;
 
     gl_Position = theMat * vec4(p1o,-500,1); EmitVertex();
     gl_Position = theMat * vec4(p1,-500,1); EmitVertex();
     gl_Position = theMat * vec4(p1o,100,1); EmitVertex();
     gl_Position = theMat * vec4(p1,100,1); EmitVertex();
     gl_Position = theMat * vec4(shifto,100,1); EmitVertex();
+    //gl_Position = theMat * vec4(xt,100,1); EmitVertex();
+    //gl_Position = theMat * vec4(mo,100,1); EmitVertex();
     gl_Position = theMat * vec4(p2,100,1); EmitVertex();
     gl_Position = theMat * vec4(p2o,100,1); EmitVertex();
     gl_Position = theMat * vec4(p2,-500,1); EmitVertex();
@@ -53,22 +86,6 @@ void main() {
     EndPrimitive();
     // be carefull with the winding...
 
-//    gl_Position = theMat * vec4(p2o,100,1); EmitVertex();
-//    gl_Position = theMat * vec4(p2,100,1); EmitVertex();
-//    gl_Position = theMat * vec4(p2o,0,1); EmitVertex();
-//    gl_Position = theMat * vec4(p2,0,1); EmitVertex();
-    
-///    gl_Position = theMat * vec4(p2,100,1); EmitVertex();
-///    gl_Position = theMat * vec4(p2,-500,1); EmitVertex();
-///    gl_Position = theMat * vec4(p2o,100,1); EmitVertex();
-///    gl_Position = theMat * vec4(p2o,-500,1); EmitVertex();
-///    gl_Position = theMat * vec4(p2cs,100,1); EmitVertex();
-///    gl_Position = theMat * vec4(p2cs,-500,1); EmitVertex();
-///    gl_Position = theMat * vec4(p1cs,100,1); EmitVertex();
-///    gl_Position = theMat * vec4(p1cs,-500,1); EmitVertex();
-///    gl_Position = theMat * vec4(p1o,100,1); EmitVertex();
-///    gl_Position = theMat * vec4(p1o,-500,1); EmitVertex();
-    
     EndPrimitive();
   } else {
   }

src/Data/Preload/Render.hs

@@ -15,6 +15,7 @@ data RenderData = RenderData
     , _lightingLineShadowShader :: Shader
     , _lightingCapShader :: Shader
     , _lightingTextureShader :: Shader
+    , _ceilingStencilShader :: Shader
     , _alphaDivideShader :: Shader
     , _windowShader :: Shader
     , _fullscreenShader :: Shader

src/Dodge/Render.hs

@@ -122,28 +122,33 @@ doDrawing' win pdata u = do
     glDepthMask GL_TRUE
     glDisable GL_BLEND
     glDepthFunc GL_LESS
-    with 1 $
+    -- clear depth and stencil buffers
-        glClearNamedFramebufferfv
+    glStencilMask 255 -- to alter the entire stencil
+    glClearNamedFramebufferfi
             (pdata ^. fboBase . _1 . unFBO)
-            GL_DEPTH
+            GL_DEPTH_STENCIL
+            0
+            1 
             0
     -- draw wall occlusions from the camera's point of view
     glDisable GL_CULL_FACE
+--    glEnable GL_STENCIL_TEST
+--    glStencilFunc 
     unless (debugOn Remove_LOS cfig) $ do
-        glUseProgram (pdata ^. lightingWallShadShader . shaderUINT)
+        glUseProgram (pdata ^. ceilingStencilShader . shaderUINT)
         glProgramUniform3f
-            (pdata ^. lightingWallShadShader . shaderUINT)
+            (pdata ^. ceilingStencilShader . shaderUINT)
             0
             vfx
             vfy
             20
         glProgramUniform1f
-            (pdata ^. lightingWallShadShader . shaderUINT)
+            (pdata ^. ceilingStencilShader . shaderUINT)
             1
             1000 -- this should be the furthest on screen distance from the viewpoint
-        glBindVertexArray $ pdata ^. lightingWallShadShader . shaderVAO . vaoName
+        glBindVertexArray $ pdata ^. ceilingStencilShader . shaderVAO . vaoName
         glDrawArrays
-            (_unPrimitiveMode $ pdata ^. lightingWallShadShader . shaderPrimitive)
+            (_unPrimitiveMode $ pdata ^. ceilingStencilShader . shaderPrimitive)
             0
             (fromIntegral trueNWalls)
     -- clear color and normals
@@ -182,12 +187,11 @@ doDrawing' win pdata u = do
     glEnable GL_STENCIL_TEST
     glStencilFunc GL_ALWAYS 0 255
     glStencilOp GL_INCR GL_INCR GL_INCR
-    with 0 $ \ptr ->
+    with 0 $
         glClearNamedFramebufferiv
             (pdata ^. fboBase . _1 . unFBO)
             GL_STENCIL
             0
-            ptr
     glDrawArrays
         (_unPrimitiveMode $ pdata ^. chasmShader . shaderPrimitive)
         0

src/Preload/Render.hs

@@ -73,6 +73,8 @@ preloadRender = do
         makeShaderUsingVAO "lighting/cap" [vert, geom] pmTriangles shPosVAO
     lightingLineShadowShad <-
         makeShaderUsingVAO "lighting/lineShadow" [vert, geom] pmLinesAdjacency shedgevao
+    ceilingstencilshader <-
+        makeShaderUsingVBO "ceiling/stencil" [vert, geom] (toFloatVAs [4]) pmPoints wallvbo
 
     putStrLn "Setup 2D shaders"
     bslist <- makeShaderVBO "dualTwoD/basic" [vert, frag] (toFloatVAs [3, 4]) pmTriangles
@@ -161,6 +163,7 @@ preloadRender = do
             , _lightingCapShader = lightingCapShad
             , _lightingLineShadowShader = lightingLineShadowShad
             , _lightingWallShadShader = lightingWallShadShad
+            , _ceilingStencilShader = ceilingstencilshader
             , _windowShader = windowshader
             , _fullscreenShader = fsShad
             , _alphaDivideShader = alphadivideshader