Shadows

2024-10-16 23:18:47 +02:00
parent a60fe82272
commit 221be140bf
6 changed files with 174 additions and 72 deletions
--- a/core/frustum.jai
+++ b/core/frustum.jai
@@ -0,0 +1,68 @@
+Frustum :: struct {
+    near_top_left: Vector3;
+    near_bottom_left: Vector3;
+    near_top_right: Vector3;
+    near_bottom_right: Vector3;
+
+    far_top_left: Vector3;
+    far_bottom_left: Vector3;
+    far_top_right: Vector3;
+    far_bottom_right: Vector3;
+}
+
+get_frustum :: (fov: float, aspect_ratio: float, z_near: float, z_far: float) -> Frustum {
+    frustum: Frustum = ---;
+
+    tan_half_fov := tan(DEGREES_TO_RADIANS * fov * 0.5);
+
+    near_z := z_near;
+    near_x := near_z * tan_half_fov;
+    near_y := near_z * tan_half_fov * aspect_ratio;
+
+    frustum.near_top_left     = .{-near_x, near_y, near_z};
+    frustum.near_bottom_left  = .{-near_x, -near_y, near_z};
+    frustum.near_top_right    = .{near_x, near_y, near_z};
+    frustum.near_bottom_right = .{near_x, -near_y, near_z};
+
+    far_z := z_far;
+    far_x := far_z * tan_half_fov;
+    far_y := far_z * tan_half_fov * aspect_ratio;
+
+    frustum.far_top_left     = .{-far_x, far_y, far_z};
+    frustum.far_bottom_left  = .{-far_x, -far_y, far_z};
+    frustum.far_top_right    = .{far_x, far_y, far_z};
+    frustum.far_bottom_right = .{far_x, -far_y, far_z};
+
+    return frustum;
+}
+
+get_frustum_aabb :: (frustum: Frustum) -> AABB {
+    aabb: AABB;
+    aabb_add(*aabb, frustum.near_top_left);
+    aabb_add(*aabb, frustum.near_bottom_left);
+    aabb_add(*aabb, frustum.near_top_right);
+    aabb_add(*aabb, frustum.near_bottom_right);
+
+    aabb_add(*aabb, frustum.far_top_left);
+    aabb_add(*aabb, frustum.far_bottom_left);
+    aabb_add(*aabb, frustum.far_top_right);
+    aabb_add(*aabb, frustum.far_bottom_right);
+
+    return aabb;
+}
+
+transform :: (frustum: Frustum, matrix: Matrix4) -> Frustum {
+    transformed_frustum: Frustum = ---;
+
+    transformed_frustum.near_top_left = transform_position(frustum.near_top_left, matrix);
+    transformed_frustum.near_bottom_left = transform_position(frustum.near_bottom_left, matrix);
+    transformed_frustum.near_top_right = transform_position(frustum.near_top_right, matrix);
+    transformed_frustum.near_bottom_right = transform_position(frustum.near_bottom_right, matrix);
+
+    transformed_frustum.far_top_left = transform_position(frustum.far_top_left, matrix);
+    transformed_frustum.far_bottom_left = transform_position(frustum.far_bottom_left, matrix);
+    transformed_frustum.far_top_right = transform_position(frustum.far_top_right, matrix);
+    transformed_frustum.far_bottom_right = transform_position(frustum.far_bottom_right, matrix);
+
+    return transformed_frustum;
+}