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TangentShader.hpp
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TangentShader.hpp
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#pragma once
#include "Vertex.h"
#include "SceneContext.h"
#include "VertexShaderMatHelper.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <memory>
#define TANGENT_SPACE
#ifdef TANGENT_SPACE
class TangentShader
{
public:
using UseDerivative = std::false_type;
struct VSOut {
glm::vec4 proj_pos;
glm::vec2 texcoord;
glm::vec3 pos_tangent;
glm::vec3 light_pos_tangent;
glm::vec3 cam_pos_tangent;
VSOut& operator+=(const VSOut& rhs)
{
proj_pos += rhs.proj_pos;
texcoord += rhs.texcoord;
pos_tangent += rhs.pos_tangent;
light_pos_tangent += rhs.light_pos_tangent;
cam_pos_tangent += rhs.cam_pos_tangent;
return *this;
}
VSOut operator+(const VSOut& rhs) const
{
return VSOut(*this) += rhs;
}
VSOut& operator*=(float v) {
proj_pos *= v;
texcoord *= v;
pos_tangent *= v;
light_pos_tangent *= v;
cam_pos_tangent *= v;
return *this;
}
VSOut operator*(float rhs) const
{
return VSOut(*this) *= rhs;
}
void Lerp(const VSOut& v0, const VSOut& v1, const VSOut& v2, float a, float b, float c) noexcept {
texcoord = v0.texcoord * a + v1.texcoord * b + v2.texcoord * c;
pos_tangent = v0.pos_tangent * a + v1.pos_tangent * b + v2.pos_tangent * c;
light_pos_tangent = v0.light_pos_tangent * a + v1.light_pos_tangent * b + v2.light_pos_tangent * c;
cam_pos_tangent = v0.cam_pos_tangent * a + v1.cam_pos_tangent * b + v2.cam_pos_tangent * c;
}
};
// make all attr to tangent space
class VertexShader : public VertexShaderMatHelper {
public:
std::shared_ptr<SceneContext> pContext;
VSOut operator()(const Vertex& v) const
{
glm::vec4 world_pos = model * glm::vec4(v.position, 1.0f);
glm::vec3 T = glm::normalize(glm::vec3(obj_to_world_normal * glm::vec4(v.tangent, 0.0)));
glm::vec3 B = glm::normalize(glm::vec3(obj_to_world_normal * glm::vec4(v.bitangent, 0.0)));
glm::vec3 N = glm::normalize(glm::vec3(obj_to_world_normal * glm::vec4(v.normal, 0.0)));
glm::mat3 TBN = glm::transpose(glm::mat3(T, B, N));
return {
proj_view * world_pos,
v.texcoord,
TBN * glm::vec3(world_pos),
TBN * pContext->light->GetPosition(),
TBN * pContext->camera_pos_cache
};
}
};
class PixelShader {
public:
std::shared_ptr<SceneContext> pContext;
float qpow(float x, int n) {
float res = 1;
while (n) {
if (n & 1) {
res *= x;
}
x *= x;
n >>= 1;
}
return res;
}
float SCALE = 0.1f; // magic, depend on result
void ParallaxMapping(std::shared_ptr<Texture2D> disp, glm::vec2& tc, const glm::vec3& V) {
// reference
// https://learnopengl-cn.github.io/05%20Advanced%20Lighting/05%20Parallax%20Mapping
// basic
//float h = disp->Sample(tc.x, tc.y).x;
//glm::vec2 p = (glm::vec2(V) / V.z) * h * SCALE;
//tc -= p; // -= when displacement map is reversed(1.0f low ~ 0.0f high), else +=
// Steep Parallax Mapping
float num_layer = 10; // can be more flexible
float h_layer = 1.0f / num_layer;
glm::vec2 p = (glm::vec2(V) / V.z) * SCALE;
glm::vec2 tc_delta = p / num_layer;
float cur_depth = 0.0f;
float cur_depth_map = disp->Sample(tc.x, tc.y).x;
while (cur_depth < cur_depth_map) {
tc -= tc_delta;
cur_depth += h_layer;
cur_depth_map = disp->Sample(tc.x, tc.y).x;
}
// Parallax Occlusion Mapping (base on Steep Parallax Mapping)
float after_depth = cur_depth_map - cur_depth; // <0
glm::vec2 prev_tc = tc + tc_delta;
float before_depth = disp->Sample(prev_tc.x, prev_tc.y).x - (cur_depth - h_layer); // >0
float weight = after_depth / (after_depth - before_depth);
tc = prev_tc * weight + tc * (1.0f - weight);
// seems not work very well at edge case when displacement map is 0.0f low ~ 1.0f high
}
glm::vec4 operator()(const VSOut& v, const VSOut& ddx, const VSOut& ddy, int modelId, int meshId)
{
glm::vec3 light_pos = v.light_pos_tangent;
glm::vec3 light_intensity = pContext->light->GetIntensity();
glm::vec3 camera_pos = v.cam_pos_tangent;
glm::vec3 light_dir = glm::normalize(light_pos - v.pos_tangent); // suppose point light
float d = glm::length(light_pos - v.pos_tangent);
light_intensity /= d * d;
glm::vec3 view_dir = glm::normalize(camera_pos - v.pos_tangent);
auto material_id = pContext->models[modelId]->meshes[meshId].material_idx;
auto& material = pContext->models[modelId]->materials[material_id];
glm::vec2 tc = v.texcoord;
if(material->disp != nullptr)
ParallaxMapping(material->disp, tc, view_dir);
glm::vec3 ka, kd, ks;
ka = material->Ka;
if (material->diffuse != nullptr)
kd = material->diffuse->Sample(tc.x, tc.y);
else
kd = material->Kd;
kd = glm::pow(kd, glm::vec3(2.2f));
if (material->specular != nullptr)
ks = material->specular->Sample(tc.x, tc.y);
else
ks = material->Ks;
assert(material->normal);
glm::vec3 N = glm::vec3(material->normal->Sample(tc.x, tc.y)) * 2.0f - 1.0f;
N = glm::normalize(N);
glm::vec3 ambient = ka * glm::vec3(1.0f); //ka * ambient light intensity
glm::vec3 diffuse = kd * light_intensity * std::max(0.0f, glm::dot(N, light_dir));
glm::vec3 half = glm::normalize(view_dir + light_dir);
glm::vec3 specular = ks * light_intensity * qpow(std::max(0.0f, glm::dot(N, half)), 150);
glm::vec3 color = ambient + diffuse + specular;
color = glm::pow(color, glm::vec3(1.0f / 2.2f));
color.r = std::max(0.0f, std::min(1.0f, color.r)); // Saturate
color.g = std::max(0.0f, std::min(1.0f, color.g));
color.b = std::max(0.0f, std::min(1.0f, color.b));
//return glm::vec4(N * 0.5f + 0.5f, 1.0f);
return glm::vec4(color, 1.0f);
}
};
public:
VertexShader vs;
PixelShader ps;
};
#else
class TangentShader
{
public:
struct VSOut {
glm::vec4 proj_pos;
glm::vec3 wrd_pos;
glm::vec2 texcoord;
glm::vec3 tangent;
glm::vec3 bitangent;
glm::vec3 normal;
VSOut& operator+=(const VSOut& rhs)
{
proj_pos += rhs.proj_pos;
wrd_pos += rhs.wrd_pos;
texcoord += rhs.texcoord;
tangent += rhs.tangent;
bitangent += rhs.bitangent;
normal += rhs.normal;
return *this;
}
VSOut operator+(const VSOut& rhs) const
{
return VSOut(*this) += rhs;
}
VSOut& operator*=(float v) {
proj_pos *= v;
wrd_pos *= v;
texcoord *= v;
tangent *= v;
bitangent *= v;
normal *= v;
return *this;
}
VSOut operator*(float rhs) const
{
return VSOut(*this) *= rhs;
}
void Lerp(const VSOut& v0, const VSOut& v1, const VSOut& v2, float a, float b, float c) noexcept {
texcoord = v0.texcoord * a + v1.texcoord * b + v2.texcoord * c;
wrd_pos = v0.wrd_pos * a + v1.wrd_pos * b + v2.wrd_pos * c;
tangent = v0.tangent * a + v1.tangent * b + v2.tangent * c;
bitangent = v0.bitangent * a + v1.bitangent * b + v2.bitangent * c;
normal = v0.normal * a + v1.normal * b + v2.normal * c;
}
};
// only make tangent space NORMAL to world space
class VertexShader : public VertexShaderMatHelper {
public:
std::shared_ptr<SceneContext> pContext;
VSOut operator()(const Vertex& v) const
{
glm::vec4 world_pos = model * glm::vec4(v.position, 1.0f);
glm::vec3 T = glm::normalize(glm::vec3(obj_to_world_normal * glm::vec4(v.tangent, 0.0)));
glm::vec3 N = glm::normalize(glm::vec3(obj_to_world_normal * glm::vec4(v.normal, 0.0)));
glm::vec3 B = glm::normalize(glm::vec3(obj_to_world_normal * glm::vec4(v.bitangent, 0.0)));
return {
proj_view * world_pos,
world_pos,
v.texcoord,
T,
B,
N
};
}
};
class PixelShader {
public:
std::shared_ptr<SceneContext> pContext;
float qpow(float x, int n) {
float res = 1;
while (n) {
if (n & 1) {
res *= x;
}
x *= x;
n >>= 1;
}
return res;
}
glm::vec4 operator()(const VSOut& v, const VSOut& ddx, const VSOut& ddy, int modelId, int meshId)
{
glm::vec3 light_pos = pContext->light->GetPosition();
glm::vec3 light_intensity = pContext->light->GetIntensity();
glm::vec3 camera_pos = pContext->camera_pos_cache;
glm::vec3 light_dir = glm::normalize(light_pos - v.wrd_pos); // suppose point light
float d = glm::length(light_pos - v.wrd_pos);
light_intensity /= d * d;
glm::vec3 view_dir = glm::normalize(camera_pos - v.wrd_pos);
auto material_id = pContext->models[modelId]->meshes[meshId].material_idx;
auto& material = pContext->models[modelId]->materials[material_id];
glm::vec3 ka, kd, ks;
ka = material->Ka;
if (material->diffuse != nullptr)
kd = material->diffuse->Sample(v.texcoord.x, v.texcoord.y);
else
kd = material->Kd;
kd = glm::pow(kd, glm::vec3(2.2f));
if (material->specular != nullptr)
ks = material->specular->Sample(v.texcoord.x, v.texcoord.y);
else
ks = material->Ks;
glm::vec3 N;
if (material->normal != nullptr) {
N = glm::vec3(material->normal->Sample(v.texcoord.x, v.texcoord.y)) * 2.0f - 1.0f;
glm::vec3 n = glm::normalize(v.normal);
glm::vec3 t = glm::normalize(v.tangent - glm::dot(n, v.tangent) * n);
glm::vec3 b = glm::normalize(v.bitangent - glm::dot(n, v.bitangent) * n - glm::dot(t, v.bitangent) * t);
N = glm::normalize(glm::mat3(t, b, n) * N);
}
else {
N = glm::normalize(v.normal);
}
glm::vec3 ambient = ka * glm::vec3(1.0f); //ka * ambient light intensity
glm::vec3 diffuse = kd * light_intensity * std::max(0.0f, glm::dot(N, light_dir));
glm::vec3 half = glm::normalize(view_dir + light_dir);
glm::vec3 specular = ks * light_intensity * qpow(std::max(0.0f, glm::dot(N, half)), 150);
glm::vec3 color = ambient + diffuse + specular;
color = glm::pow(color, glm::vec3(1.0f / 2.2f));
color.r = std::max(0.0f, std::min(1.0f, color.r)); // Saturate
color.g = std::max(0.0f, std::min(1.0f, color.g));
color.b = std::max(0.0f, std::min(1.0f, color.b));
//return glm::vec4(N * 0.5f + 0.5f, 1.0f);
return glm::vec4(color, 1.0f);
}
};
public:
VertexShader vs;
PixelShader ps;
};
#endif // TANGENT_SPACE