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#ifndef SHADERS_SIMPLE_SHADERS_HPP
#define SHADERS_SIMPLE_SHADERS_HPP
#include <algorithm>
#include <cmath>
#include <vector>
#include "fb/pixfb.hpp"
#include "math/vector.hpp"
#include "math/mat4.hpp"
#include "o3d/vertex.hpp"
namespace engine::shaders {
class SimpleShaders {
public:
using fb_type = engine::fb::PixelFrameBuffer;
engine::math::Matrix4 model_mat, view_mat, proj_mat, final_mat;
int w, h;
std::vector<engine::math::Vector4> pixels;
SimpleShaders(int w, int h, unsigned char* pixels);
void set_view(const engine::math::Matrix4& view_mat, const engine::math::Matrix4& proj_mat);
void set_model(const engine::math::Matrix4& model_mat);
constexpr engine::o3d::Vertex vertex(const engine::math::Vector3& vertex, const engine::math::Vector3& normal, const engine::math::Vector2& uv) const & {
return { final_mat * engine::math::Vector4 { vertex, 1.f }, (model_mat * engine::math::Vector4 { normal, 0.f }).xyz(), uv };
}
constexpr engine::math::Vector4 fragment(int /* x */, int /* y */, const engine::math::Vector3& /* loc */, const engine::math::Vector3& /* normal */,
const engine::math::Vector2& uv) const & {
// auto u = vd.world_loc - camera->transform.loc;
// float u_len_sq = u.length_squared();
// u = u.normalize();
// float attenuation = camera->transform.rot.rot({ 0.f, 0.f, -1.f }).dot(u);
// if (attenuation < .7f) attenuation = 0.f;
// else if (attenuation > .8f) attenuation = 1.f;
// else attenuation = (attenuation - .7f) / .1f;
// float light = -normal.normalize().dot(u) / u_len_sq;
// if (light < 0.f) light = 0.f;
// float final_light = .003f + light * attenuation * .8f * .997f;
// if (final_light > 1.f) final_light = 1.f;
// // gamma correction
// // TODO: improve, we shouldn't do it here
// if (final_light <= .0031308f)
// final_light = final_light * 12.92f;
// else
// final_light = 1.055f * pow(final_light, 1.f / 2.4f) - .055f;
// std::uint32_t c = (int) (final_light * 255.f);
// pixels_vector[x + y * w] = 0xff000000 | c << 16 | c << 8 | c;
float txf, tyf;
float fac_x = std::modf(uv.x * static_cast<float>(w) - .5f, &txf);
float fac_y = std::modf(uv.y * static_cast<float>(h) - .5f, &tyf);
int tx0 = std::clamp(static_cast<int>(txf) + 0, 0, w);
int tx1 = std::clamp(static_cast<int>(txf) + 1, 0, w);
int ty0 = std::clamp(static_cast<int>(tyf) + 0, 0, h);
int ty1 = std::clamp(static_cast<int>(tyf) + 1, 0, h);
return
((1.f - fac_x) * (1.f - fac_y)) * pixels[tx0 + ty0 * w]
+ (fac_x * (1.f - fac_y)) * pixels[tx1 + ty0 * w]
+ ((1.f - fac_x) * fac_y ) * pixels[tx0 + ty1 * w]
+ (fac_x * fac_y ) * pixels[tx1 + ty1 * w];
}
};
}
#endif // SHADERS_SIMPLE_SHADERS_HPP
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