From fa04ebc603a7bf742c64724ede23cfa010fb3c4c Mon Sep 17 00:00:00 2001
From: omniscient <17525998+omnisci3nce@users.noreply.github.com>
Date: Wed, 31 Jul 2024 12:26:22 +1000
Subject: grid is not really working

---
 assets/shaders/grid.vert | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

(limited to 'assets/shaders/grid.vert')

diff --git a/assets/shaders/grid.vert b/assets/shaders/grid.vert
index bdfa477..592cbfc 100644
--- a/assets/shaders/grid.vert
+++ b/assets/shaders/grid.vert
@@ -6,12 +6,37 @@ uniform Camera {
   vec4 viewPos;
 } cam;
 
+out vec3 nearPoint;
+out vec3 farPoint;
+out float near;
+out float far;
+out mat4 fragView;
+out mat4 fragProj;
+
 // Grid position are in xy clipped space
 vec3 gridPlane[6] = vec3[](
     vec3(1, 1, 0), vec3(-1, -1, 0), vec3(-1, 1, 0),
     vec3(-1, -1, 0), vec3(1, 1, 0), vec3(1, -1, 0)
 );
-// normal vertice projection
+
+vec3 UnprojectPoint(float x, float y, float z, mat4 view, mat4 projection) {
+    mat4 viewInv = inverse(view);
+    mat4 projInv = inverse(projection);
+    vec4 unprojectedPoint =  viewInv * projInv * vec4(x, y, z, 1.0);
+    return unprojectedPoint.xyz / unprojectedPoint.w;
+}
+
+// normal vertex projection
 void main() {
-    gl_Position = cam.proj * cam.view * vec4(gridPlane[gl_VertexID].xyz, 1.0);
+    // gl_Position = cam.proj * cam.view * vec4(gridPlane[gl_VertexID].xyz, 1.0);
+    vec3 p = gridPlane[gl_VertexID].xyz;
+    nearPoint = UnprojectPoint(p.x, p.y, -1.0, cam.view, cam.proj).xyz; // unprojecting on the near plane
+    farPoint = UnprojectPoint(p.x, p.y, 1.0, cam.view, cam.proj).xyz; // unprojecting on the far plane
+
+    fragView = cam.view;
+    fragProj = cam.proj;
+    near = 0.01;
+    far = 100.0;
+
+    gl_Position = vec4(p, 1.0); // using directly the clipped coordinates
 }
\ No newline at end of file
-- 
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