Files
axyz/resources/Shaders/GridFrustum.comp.glsl
T

75 lines
2.2 KiB
GLSL

#version 430
#define TILE_SIZE 16
uniform mat4 P;
uniform vec2 ScreenDimensions;
struct Plane {
vec3 Normal;
float d;
};
struct Frustum {
Plane Planes[4];
};
layout (std430, binding = 0) buffer FrustumBuffer
{
Frustum Data[];
} Frustums;
vec4 ConvertToView(vec4 ScreenCoords)
{
vec2 normalizedScreenCoords = ScreenCoords.xy / ScreenDimensions;
vec4 clipSpace = vec4( vec2(normalizedScreenCoords.x, normalizedScreenCoords.y) * 2.0 - 1.0, ScreenCoords.z, ScreenCoords.w);
vec4 view = inverse(P) * clipSpace;
view = view / view.w;
return view;
}
Plane ComputePlane( vec3 p0, vec3 p1, vec3 p2 )
{
Plane plane;
vec3 v0 = p1 - p0;
vec3 v2 = p2 - p0;
plane.Normal = normalize( cross( v0, v2 ) );
plane.d = dot( vec3(plane.Normal), p0 ); // Always 0 probably
return plane;
}
layout (local_size_x = 16, local_size_y = 16, local_size_z = 1) in;
void main ()
{
//Top-Left = 0 | Top-Right = 1
//Bottom-Left = 2 | Bottom-Right = 3
vec4 ScreenCoords[4];
ScreenCoords[0] = vec4(gl_GlobalInvocationID.x * TILE_SIZE, (gl_GlobalInvocationID.y + 1) * TILE_SIZE, -1.0, 1.0);
ScreenCoords[1] = vec4((gl_GlobalInvocationID.x + 1) * TILE_SIZE, (gl_GlobalInvocationID.y + 1) * TILE_SIZE, -1.0, 1.0);
ScreenCoords[2] = vec4(gl_GlobalInvocationID.x * TILE_SIZE, (gl_GlobalInvocationID.y) * TILE_SIZE, -1.0, 1.0);
ScreenCoords[3] = vec4((gl_GlobalInvocationID.x + 1) * TILE_SIZE, (gl_GlobalInvocationID.y) * TILE_SIZE, -1.0, 1.0);
vec3 ViewVectors[4];
for(int i = 0; i < 4; i++) {
ViewVectors[i] = vec3(ConvertToView(ScreenCoords[i]));
}
vec3 EyePos = vec3(0.0, 0.0 ,0.0);
Frustum f;
f.Planes[0] = ComputePlane(EyePos, ViewVectors[2], ViewVectors[0]); // left plane
f.Planes[1] = ComputePlane(EyePos, ViewVectors[1], ViewVectors[3]); // right plane
f.Planes[2] = ComputePlane(EyePos, ViewVectors[0], ViewVectors[1]); // top plane
f.Planes[3] = ComputePlane(EyePos, ViewVectors[3], ViewVectors[2]); // bottom plane
if ( gl_GlobalInvocationID.x < ScreenDimensions.x / TILE_SIZE && gl_GlobalInvocationID.y < ScreenDimensions.y / TILE_SIZE ) { // inside the screen
Frustums.Data[gl_GlobalInvocationID.x + gl_GlobalInvocationID.y*int(ScreenDimensions.x/TILE_SIZE)] = f;
}
}