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https://github.com/RGBCube/serenity
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LibGL+LibGPU+LibSoftGPU: Implement and expose glClipPlane
This commit implements glClipPlane and its supporting calls, backed by new support for user-defined clip planes in the software GPU clipper. This fixes some visual bugs seen in the Quake III port, in which mirrors would only reflect correctly from close distances.
This commit is contained in:
RKBethke
Linus Groh
parent
bc2f738a84
commit
0836912a6d
14 changed files with 193 additions and 63 deletions
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@ -7,6 +7,7 @@
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/StdLibExtras.h>
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#include <AK/Vector.h>
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#include <LibGPU/Vertex.h>
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#include <LibGfx/Vector4.h>
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@ -17,40 +18,42 @@ namespace SoftGPU {
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template<Clipper::ClipPlane plane>
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static constexpr bool point_within_clip_plane(FloatVector4 const& vertex)
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{
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if constexpr (plane == Clipper::ClipPlane::LEFT)
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if constexpr (plane == Clipper::ClipPlane::Left)
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return vertex.x() >= -vertex.w();
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else if constexpr (plane == Clipper::ClipPlane::RIGHT)
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else if constexpr (plane == Clipper::ClipPlane::Right)
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return vertex.x() <= vertex.w();
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else if constexpr (plane == Clipper::ClipPlane::TOP)
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else if constexpr (plane == Clipper::ClipPlane::Top)
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return vertex.y() <= vertex.w();
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else if constexpr (plane == Clipper::ClipPlane::BOTTOM)
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else if constexpr (plane == Clipper::ClipPlane::Bottom)
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return vertex.y() >= -vertex.w();
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else if constexpr (plane == Clipper::ClipPlane::NEAR)
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else if constexpr (plane == Clipper::ClipPlane::Near)
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return vertex.z() >= -vertex.w();
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else if constexpr (plane == Clipper::ClipPlane::FAR)
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else if constexpr (plane == Clipper::ClipPlane::Far)
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return vertex.z() <= vertex.w();
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return false;
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}
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template<Clipper::ClipPlane plane>
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static constexpr GPU::Vertex clip_intersection_point(GPU::Vertex const& p1, GPU::Vertex const& p2)
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static bool point_within_user_plane(FloatVector4 const& vertex, FloatVector4 const& user_plane)
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{
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constexpr FloatVector4 clip_plane_normals[] = {
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{ 1, 0, 0, 1 }, // Left Plane
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{ -1, 0, 0, 1 }, // Right Plane
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{ 0, -1, 0, 1 }, // Top Plane
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{ 0, 1, 0, 1 }, // Bottom plane
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{ 0, 0, 1, 1 }, // Near Plane
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{ 0, 0, -1, 1 } // Far Plane
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};
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constexpr auto clip_plane_normal = clip_plane_normals[to_underlying(plane)];
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return vertex.dot(user_plane) >= 0;
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}
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// See https://www.microsoft.com/en-us/research/wp-content/uploads/1978/01/p245-blinn.pdf
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// "Clipping Using Homogeneous Coordinates" Blinn/Newell, 1978
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// Clip plane normals have W=1 so the vertices' W coordinates are included in x1 and x2.
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template<Clipper::ClipPlane plane>
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bool point_within_plane(GPU::Vertex const& vertex, FloatVector4 const& user_plane)
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{
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if constexpr (plane == Clipper::ClipPlane::User)
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return point_within_user_plane(vertex.eye_coordinates, user_plane);
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else
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return point_within_clip_plane<plane>(vertex.clip_coordinates);
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}
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auto const x1 = clip_plane_normal.dot(p1.clip_coordinates);
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auto const x2 = clip_plane_normal.dot(p2.clip_coordinates);
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template<Clipper::ClipPlane plane>
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static GPU::Vertex clip_intersection_point(GPU::Vertex const& p1, GPU::Vertex const& p2, FloatVector4 const& plane_normal)
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{
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auto p1_coordinates = (plane == Clipper::ClipPlane::User) ? p1.eye_coordinates : p1.clip_coordinates;
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auto p2_coordinates = (plane == Clipper::ClipPlane::User) ? p2.eye_coordinates : p2.clip_coordinates;
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auto x1 = plane_normal.dot(p1_coordinates);
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auto x2 = plane_normal.dot(p2_coordinates);
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auto const a = x1 / (x1 - x2);
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GPU::Vertex out;
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@ -65,7 +68,7 @@ static constexpr GPU::Vertex clip_intersection_point(GPU::Vertex const& p1, GPU:
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}
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template<Clipper::ClipPlane plane>
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FLATTEN static constexpr void clip_plane(Vector<GPU::Vertex>& input_list, Vector<GPU::Vertex>& output_list)
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FLATTEN static void clip_plane(Vector<GPU::Vertex>& input_list, Vector<GPU::Vertex>& output_list, FloatVector4 const& clip_plane)
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{
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output_list.clear_with_capacity();
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@ -74,20 +77,20 @@ FLATTEN static constexpr void clip_plane(Vector<GPU::Vertex>& input_list, Vector
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return;
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auto const* prev_vec = &input_list.data()[0];
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auto is_prev_point_within_clip_plane = point_within_clip_plane<plane>(prev_vec->clip_coordinates);
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auto is_prev_point_within_plane = point_within_plane<plane>(*prev_vec, clip_plane);
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for (size_t i = 1; i <= input_list_size; i++) {
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auto const& curr_vec = input_list[i % input_list_size];
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auto const is_curr_point_within_clip_plane = point_within_clip_plane<plane>(curr_vec.clip_coordinates);
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auto const is_curr_point_within_plane = point_within_plane<plane>(curr_vec, clip_plane);
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if (is_curr_point_within_clip_plane != is_prev_point_within_clip_plane)
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output_list.append(clip_intersection_point<plane>(*prev_vec, curr_vec));
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if (is_curr_point_within_plane != is_prev_point_within_plane)
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output_list.append(clip_intersection_point<plane>(*prev_vec, curr_vec, clip_plane));
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if (is_curr_point_within_clip_plane)
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if (is_curr_point_within_plane)
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output_list.append(curr_vec);
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prev_vec = &curr_vec;
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is_prev_point_within_clip_plane = is_curr_point_within_clip_plane;
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is_prev_point_within_plane = is_curr_point_within_plane;
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}
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}
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@ -97,9 +100,9 @@ void Clipper::clip_points_against_frustum(Vector<GPU::Vertex>& vertices)
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for (auto& vertex : vertices) {
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auto const coords = vertex.clip_coordinates;
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if (point_within_clip_plane<ClipPlane::LEFT>(coords) && point_within_clip_plane<ClipPlane::RIGHT>(coords)
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&& point_within_clip_plane<ClipPlane::TOP>(coords) && point_within_clip_plane<ClipPlane::BOTTOM>(coords)
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&& point_within_clip_plane<ClipPlane::NEAR>(coords) && point_within_clip_plane<ClipPlane::FAR>(coords))
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if (point_within_clip_plane<ClipPlane::Left>(coords) && point_within_clip_plane<ClipPlane::Right>(coords)
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&& point_within_clip_plane<ClipPlane::Top>(coords) && point_within_clip_plane<ClipPlane::Bottom>(coords)
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&& point_within_clip_plane<ClipPlane::Near>(coords) && point_within_clip_plane<ClipPlane::Far>(coords))
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m_vertex_buffer.append(vertex);
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}
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@ -107,39 +110,61 @@ void Clipper::clip_points_against_frustum(Vector<GPU::Vertex>& vertices)
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vertices.extend(m_vertex_buffer);
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}
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constexpr FloatVector4 clip_plane_eqns[] = {
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{ 1, 0, 0, 1 }, // Left Plane
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{ -1, 0, 0, 1 }, // Right Plane
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{ 0, -1, 0, 1 }, // Top Plane
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{ 0, 1, 0, 1 }, // Bottom plane
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{ 0, 0, 1, 1 }, // Near Plane
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{ 0, 0, -1, 1 } // Far Plane
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};
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template<Clipper::ClipPlane plane>
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static constexpr bool constrain_line_within_plane(GPU::Vertex& from, GPU::Vertex& to)
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{
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constexpr auto clip_plane_eqn = clip_plane_eqns[to_underlying(plane)];
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auto from_within_plane = point_within_clip_plane<plane>(from.clip_coordinates);
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auto to_within_plane = point_within_clip_plane<plane>(to.clip_coordinates);
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if (!from_within_plane && !to_within_plane)
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return false;
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if (!from_within_plane)
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from = clip_intersection_point<plane>(from, to);
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from = clip_intersection_point<plane>(from, to, clip_plane_eqn);
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else if (!to_within_plane)
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to = clip_intersection_point<plane>(from, to);
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to = clip_intersection_point<plane>(from, to, clip_plane_eqn);
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return true;
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}
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bool Clipper::clip_line_against_frustum(GPU::Vertex& from, GPU::Vertex& to)
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{
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return constrain_line_within_plane<ClipPlane::LEFT>(from, to)
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&& constrain_line_within_plane<ClipPlane::RIGHT>(from, to)
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&& constrain_line_within_plane<ClipPlane::TOP>(from, to)
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&& constrain_line_within_plane<ClipPlane::BOTTOM>(from, to)
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&& constrain_line_within_plane<ClipPlane::NEAR>(from, to)
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&& constrain_line_within_plane<ClipPlane::FAR>(from, to);
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return constrain_line_within_plane<ClipPlane::Left>(from, to)
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&& constrain_line_within_plane<ClipPlane::Right>(from, to)
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&& constrain_line_within_plane<ClipPlane::Top>(from, to)
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&& constrain_line_within_plane<ClipPlane::Bottom>(from, to)
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&& constrain_line_within_plane<ClipPlane::Near>(from, to)
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&& constrain_line_within_plane<ClipPlane::Far>(from, to);
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}
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void Clipper::clip_triangle_against_frustum(Vector<GPU::Vertex>& input_verts)
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{
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// FIXME C++23. Static reflection will provide looping over all enum values.
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clip_plane<ClipPlane::LEFT>(input_verts, m_vertex_buffer);
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clip_plane<ClipPlane::RIGHT>(m_vertex_buffer, input_verts);
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clip_plane<ClipPlane::TOP>(input_verts, m_vertex_buffer);
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clip_plane<ClipPlane::BOTTOM>(m_vertex_buffer, input_verts);
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clip_plane<ClipPlane::NEAR>(input_verts, m_vertex_buffer);
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clip_plane<ClipPlane::FAR>(m_vertex_buffer, input_verts);
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clip_plane<ClipPlane::Left>(input_verts, m_vertex_buffer, clip_plane_eqns[0]);
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clip_plane<ClipPlane::Right>(m_vertex_buffer, input_verts, clip_plane_eqns[1]);
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clip_plane<ClipPlane::Top>(input_verts, m_vertex_buffer, clip_plane_eqns[2]);
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clip_plane<ClipPlane::Bottom>(m_vertex_buffer, input_verts, clip_plane_eqns[3]);
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clip_plane<ClipPlane::Near>(input_verts, m_vertex_buffer, clip_plane_eqns[4]);
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clip_plane<ClipPlane::Far>(m_vertex_buffer, input_verts, clip_plane_eqns[5]);
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}
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void Clipper::clip_triangle_against_user_defined(Vector<GPU::Vertex>& input_verts, Vector<FloatVector4>& user_planes)
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{
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// FIXME: Also implement user plane support for points and lines
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auto& in = input_verts;
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auto& out = m_vertex_buffer;
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for (auto const& plane : user_planes) {
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clip_plane<ClipPlane::User>(in, out, plane);
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swap(in, out);
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}
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}
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}
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@ -16,12 +16,13 @@ namespace SoftGPU {
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class Clipper final {
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public:
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enum class ClipPlane : u8 {
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LEFT = 0,
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RIGHT,
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TOP,
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BOTTOM,
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NEAR,
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FAR
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Left = 0,
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Right,
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Top,
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Bottom,
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Near,
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Far,
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User, // Within view space
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};
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Clipper() = default;
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@ -29,6 +30,7 @@ public:
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void clip_points_against_frustum(Vector<GPU::Vertex>& vertices);
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bool clip_line_against_frustum(GPU::Vertex& from, GPU::Vertex& to);
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void clip_triangle_against_frustum(Vector<GPU::Vertex>& input_vecs);
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void clip_triangle_against_user_defined(Vector<GPU::Vertex>& input_verts, Vector<FloatVector4>& user_planes);
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private:
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Vector<GPU::Vertex> m_vertex_buffer;
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@ -19,6 +19,7 @@ namespace SoftGPU {
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static constexpr bool ENABLE_STATISTICS_OVERLAY = false;
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static constexpr int MILLISECONDS_PER_STATISTICS_PERIOD = 500;
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static constexpr int NUM_LIGHTS = 8;
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static constexpr int MAX_CLIP_PLANES = 6;
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static constexpr int SUBPIXEL_BITS = 6;
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// See: https://www.khronos.org/opengl/wiki/Common_Mistakes#Texture_edge_color_problem
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@ -826,6 +826,7 @@ GPU::DeviceInfo Device::info() const
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.device_name = "SoftGPU",
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.num_texture_units = GPU::NUM_SAMPLERS,
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.num_lights = NUM_LIGHTS,
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.max_clip_planes = MAX_CLIP_PLANES,
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.stencil_bits = sizeof(GPU::StencilType) * 8,
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.supports_npot_textures = true,
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};
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@ -1175,6 +1176,9 @@ void Device::draw_primitives(GPU::PrimitiveType primitive_type, FloatMatrix4x4 c
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m_clipped_vertices.append(triangle.vertices[2]);
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m_clipper.clip_triangle_against_frustum(m_clipped_vertices);
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if (m_clip_planes.size() > 0)
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m_clipper.clip_triangle_against_user_defined(m_clipped_vertices, m_clip_planes);
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if (m_clipped_vertices.size() < 3)
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continue;
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@ -1497,6 +1501,11 @@ void Device::set_raster_position(GPU::RasterPosition const& raster_position)
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m_raster_position = raster_position;
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}
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void Device::set_clip_planes(Vector<FloatVector4> const& clip_planes)
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{
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m_clip_planes = clip_planes;
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}
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void Device::set_raster_position(FloatVector4 const& position, FloatMatrix4x4 const& model_view_transform, FloatMatrix4x4 const& projection_transform)
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{
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auto const eye_coordinates = model_view_transform * position;
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@ -68,6 +68,7 @@ public:
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virtual void set_light_state(unsigned, GPU::Light const&) override;
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virtual void set_material_state(GPU::Face, GPU::Material const&) override;
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virtual void set_stencil_configuration(GPU::Face, GPU::StencilConfiguration const&) override;
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virtual void set_clip_planes(Vector<FloatVector4> const&) override;
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virtual GPU::RasterPosition raster_position() const override { return m_raster_position; }
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virtual void set_raster_position(GPU::RasterPosition const& raster_position) override;
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@ -107,6 +108,7 @@ private:
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Array<GPU::Light, NUM_LIGHTS> m_lights;
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Array<GPU::Material, 2u> m_materials;
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GPU::RasterPosition m_raster_position;
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Vector<FloatVector4> m_clip_planes;
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Array<GPU::StencilConfiguration, 2u> m_stencil_configuration;
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};
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