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LibGL+LibSoftGPU: Move rendering related code to LibSoftGPU library

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This introduces a new library, LibSoftGPU, that incorporates all
rendering related features that formerly resided within LibGL itself.

Going forward we will make both libraries completely independent from
each other allowing LibGL to load different, possibly accelerated,
rendering backends.
This commit is contained in:
Stephan Unverwerth 2021-12-16 20:32:38 +01:00 • committed by Brian Gianforcaro
parent 46b1c2d609
commit ad3d5d43bd
12 changed files with 58 additions and 45 deletions
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83
Userland/Libraries/LibSoftGPU/Clipper.cpp Normal file
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/*
* Copyright (c) 2021, Jesse Buhagiar <jooster669@gmail.com>
* Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Format.h>
#include <AK/ScopeGuard.h>
#include <LibSoftGPU/Clipper.h>
namespace SoftGPU {
bool Clipper::point_within_clip_plane(const FloatVector4& vertex, ClipPlane plane)
{
switch (plane) {
case ClipPlane::LEFT:
return vertex.x() >= -vertex.w();
case ClipPlane::RIGHT:
return vertex.x() <= vertex.w();
case ClipPlane::TOP:
return vertex.y() <= vertex.w();
case ClipPlane::BOTTOM:
return vertex.y() >= -vertex.w();
case ClipPlane::NEAR:
return vertex.z() >= -vertex.w();
case ClipPlane::FAR:
return vertex.z() <= vertex.w();
}
return false;
}
GL::GLVertex Clipper::clip_intersection_point(const GL::GLVertex& p1, const GL::GLVertex& p2, ClipPlane plane_index)
{
// See https://www.microsoft.com/en-us/research/wp-content/uploads/1978/01/p245-blinn.pdf
// "Clipping Using Homogeneous Coordinates" Blinn/Newell, 1978
float w1 = p1.position.w();
float w2 = p2.position.w();
float x1 = clip_plane_normals[plane_index].dot(p1.position);
float x2 = clip_plane_normals[plane_index].dot(p2.position);
float a = (w1 + x1) / ((w1 + x1) - (w2 + x2));
GL::GLVertex out;
out.position = p1.position * (1 - a) + p2.position * a;
out.color = p1.color * (1 - a) + p2.color * a;
out.tex_coord = p1.tex_coord * (1 - a) + p2.tex_coord * a;
return out;
}
void Clipper::clip_triangle_against_frustum(Vector<GL::GLVertex>& input_verts)
{
list_a = input_verts;
list_b.clear_with_capacity();
auto read_from = &list_a;
auto write_to = &list_b;
for (size_t plane = 0; plane < NUMBER_OF_CLIPPING_PLANES; plane++) {
write_to->clear_with_capacity();
// Save me, C++23
for (size_t i = 0; i < read_from->size(); i++) {
const auto& curr_vec = read_from->at((i + 1) % read_from->size());
const auto& prev_vec = read_from->at(i);
if (point_within_clip_plane(curr_vec.position, static_cast<ClipPlane>(plane))) {
if (!point_within_clip_plane(prev_vec.position, static_cast<ClipPlane>(plane))) {
auto intersect = clip_intersection_point(prev_vec, curr_vec, static_cast<ClipPlane>(plane));
write_to->append(intersect);
}
write_to->append(curr_vec);
} else if (point_within_clip_plane(prev_vec.position, static_cast<ClipPlane>(plane))) {
auto intersect = clip_intersection_point(prev_vec, curr_vec, static_cast<ClipPlane>(plane));
write_to->append(intersect);
}
}
swap(write_to, read_from);
}
input_verts = *read_from;
}
}