68 lines
2.4 KiB
Plaintext
68 lines
2.4 KiB
Plaintext
Frustum :: struct {
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near_top_left: Vector3;
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near_bottom_left: Vector3;
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near_top_right: Vector3;
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near_bottom_right: Vector3;
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far_top_left: Vector3;
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far_bottom_left: Vector3;
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far_top_right: Vector3;
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far_bottom_right: Vector3;
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}
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get_frustum :: (fov: float, aspect_ratio: float, z_near: float, z_far: float) -> Frustum {
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frustum: Frustum = ---;
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tan_half_fov := tan(DEGREES_TO_RADIANS * fov * 0.5);
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near_z := z_near;
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near_x := near_z * tan_half_fov;
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near_y := near_z * tan_half_fov * aspect_ratio;
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frustum.near_top_left = .{-near_x, near_y, near_z};
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frustum.near_bottom_left = .{-near_x, -near_y, near_z};
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frustum.near_top_right = .{near_x, near_y, near_z};
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frustum.near_bottom_right = .{near_x, -near_y, near_z};
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far_z := z_far;
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far_x := far_z * tan_half_fov;
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far_y := far_z * tan_half_fov * aspect_ratio;
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frustum.far_top_left = .{-far_x, far_y, far_z};
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frustum.far_bottom_left = .{-far_x, -far_y, far_z};
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frustum.far_top_right = .{far_x, far_y, far_z};
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frustum.far_bottom_right = .{far_x, -far_y, far_z};
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return frustum;
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}
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get_frustum_aabb :: (frustum: Frustum) -> AABB {
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aabb: AABB;
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aabb_add(*aabb, frustum.near_top_left);
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aabb_add(*aabb, frustum.near_bottom_left);
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aabb_add(*aabb, frustum.near_top_right);
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aabb_add(*aabb, frustum.near_bottom_right);
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aabb_add(*aabb, frustum.far_top_left);
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aabb_add(*aabb, frustum.far_bottom_left);
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aabb_add(*aabb, frustum.far_top_right);
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aabb_add(*aabb, frustum.far_bottom_right);
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return aabb;
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}
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transform :: (frustum: Frustum, matrix: Matrix4) -> Frustum {
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transformed_frustum: Frustum = ---;
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transformed_frustum.near_top_left = transform_position(frustum.near_top_left, matrix);
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transformed_frustum.near_bottom_left = transform_position(frustum.near_bottom_left, matrix);
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transformed_frustum.near_top_right = transform_position(frustum.near_top_right, matrix);
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transformed_frustum.near_bottom_right = transform_position(frustum.near_bottom_right, matrix);
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transformed_frustum.far_top_left = transform_position(frustum.far_top_left, matrix);
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transformed_frustum.far_bottom_left = transform_position(frustum.far_bottom_left, matrix);
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transformed_frustum.far_top_right = transform_position(frustum.far_top_right, matrix);
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transformed_frustum.far_bottom_right = transform_position(frustum.far_bottom_right, matrix);
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return transformed_frustum;
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} |