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Start implementing ceiling stencil shader

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justin
2025-11-01 11:24:08 +00:00
parent 71006e24fd
commit d35a41944c
4 changed files with 60 additions and 35 deletions
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shader/lighting/wallShadow.geom
+42 -25
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@@ -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) {
return sign(-startV.x * testV.y + startV.y * testV.x);
float detV(vec2 p, vec2 q) {
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
// of the wall. Necessary in case the light source is very close to the
// wall
vec2 xxxy = p1 + (0.25 * (p2 -p1));
vec2 xt = shift(xxxy);
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 ? p1cs : shift(p1) );
vec2 p2cs = p2 + closeshift;
vec2 p2o = vec2( distance(p2,lightPos.xy) > rad ? p2cs : shift(p2) );
//vec2 p1o = vec2( distance(p1,lightPos.xy) > rad ? p1 : shift(p1) );
vec2 p1o = xoo;
//vec2 p2o = vec2( distance(p2,lightPos.xy) > rad ? p2 : 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 {
}