Run shadow render pass and compute light position in vertex shaders

floor-vert.glsl

@@ -1,10 +1,12 @@
 #version 450
 
 layout(location = 0) out vec3 frag_normal;
+layout(location = 1) out vec4 light_pos;
 
-layout(push_constant) uniform vp_t {
-	mat4 transform;
-} vp;
+layout(push_constant) uniform push_t {
+	mat4 vp;
+	mat4 light_vp;
+} push;
 
 vec2 vertices[4] = vec2[](
 	vec2(-1, -1),
@@ -15,6 +17,8 @@ vec2 vertices[4] = vec2[](
 
 void main() {
 	const vec2 pos = 3 * vertices[gl_VertexIndex];
-	gl_Position = vp.transform * vec4(pos.x, 0, pos.y, 1);
+	const vec4 world_pos = vec4(pos.x, 0, pos.y, 1);
+	gl_Position = push.vp * world_pos;
 	frag_normal = vec3(0, 1, 0);
+	light_pos = push.light_vp * world_pos;
 }