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//
// Created by Michael Foiani on 11/4/23.
//
#include "raytracer/raytracer.h"
glm::vec2 getUVCube(glm::vec4 pObject) {
float u = -1.f,v = -1.f;
if (RayTracer::floatEquals(pObject.y, -.5f)) // neg y, bottom face
{
u = pObject.x + 0.5f;
v = pObject.z + 0.5f;
}
else if (RayTracer::floatEquals(pObject.y, .5f)) // pos y, top face
{
u = pObject.x + 0.5f;
v = .5f - pObject.z; // flip z
}
else if (RayTracer::floatEquals(pObject.x, -.5f)) // neg x, left face
{
u = pObject.z + 0.5f;
v = pObject.y + 0.5f;
}
else if (RayTracer::floatEquals(pObject.x, .5f)) // pos x, right face
{
u = .5f - pObject.z; // flip z
v = pObject.y + 0.5f;
}
else if (RayTracer::floatEquals(pObject.z, -.5f)) // neg z, back face
{
u = .5f - pObject.x; // flip x
v = pObject.y + 0.5f;
}
else if (RayTracer::floatEquals(pObject.z, .5f)) // pos z, front face
{
u = pObject.x + 0.5f;
v = pObject.y + 0.5f;
}
return {u, v};
}
glm::vec2 getUVCone(glm::vec4 pObject) {
float u, v;
// three cases -> 1) top cap, 2) bottom cap, 3) conical side
if (RayTracer::floatEquals(pObject.y, -.5f)) // 1) bottom cap
{
u = pObject.x + 0.5f;
v = pObject.z + 0.5f;
}
else if (RayTracer::floatEquals(pObject.y, .5f)) // 2) top cap
{
u = pObject.x + 0.5f;
v = 0.5f - pObject.z; // flip z
}
else // case 3) conical face
{
// get u from theta zpos and xpos
float theta = glm::atan(pObject.x, pObject.z);
u = (theta + 1.5 * M_PI) / (2 * M_PI);
// get v from ypos, trivial
v = pObject.y + 0.5f;
}
return {u, v};
}
glm::vec2 getUVCylinder(glm::vec4 pObject) {
float u, v;
// three cases -> top cap, bottom cap, cylindrical side
if (RayTracer::floatEquals(pObject.y, -.5f)) // 1) bottom cap
{
u = pObject.x + 0.5f;
v = pObject.z + 0.5f;
}
else if (RayTracer::floatEquals(pObject.y, .5f)) // 2) top cap
{
u = pObject.x + 0.5f;
v = 0.5f - pObject.z; // flip z
}
else // case 3) cylindrical face
{
// get u from theta zpos and xpos
float theta = glm::atan(pObject.x, pObject.z);
u = (theta + 1.5 * M_PI) / (2 * M_PI);
// get v from ypos and origin
v = pObject.y + 0.5f;
}
return {u, v};
}
glm::vec2 getUVMesh(glm::vec4 pObject) {
return glm::vec2(-1.f);
}
glm::vec2 getUVSphere(glm::vec4 pObject) {
float u = -1.f,v = -1.f;
// get u from theta between xpos and zpos
// get u from theta zpos and xpos
float theta = glm::atan(pObject.x, pObject.z);
u = (theta + 1.5 * M_PI) / (2 * M_PI);
// get v from phi from ypos and origin
float height = pObject.y/.5f;
height = std::clamp(height, -1.f, 1.f);
float phi = glm::asin(height);
v = phi / M_PI + .5f;
return {u, v};
}
glm::vec4 RayTracer::interpolateTexture(
glm::vec4 pObject,
const RenderShapeData &shape,
glm::vec4 illuminationToInterpolate)
{
auto material = shape.primitive.material;
if (!material.textureMap.isUsed)
{
// return if no texture
return illuminationToInterpolate;
}
// determine uv based on shape
glm::vec2 uv;
switch (shape.primitive.type)
{
case PrimitiveType::PRIMITIVE_CUBE:
uv = getUVCube(pObject);
break;
case PrimitiveType::PRIMITIVE_CONE:
uv = getUVCone(pObject);
break;
case PrimitiveType::PRIMITIVE_CYLINDER:
uv = getUVCylinder(pObject);
break;
case PrimitiveType::PRIMITIVE_SPHERE:
uv = getUVSphere(pObject);
break;
case PrimitiveType::PRIMITIVE_MESH:
uv = getUVMesh(pObject);
break;
}
float u = uv.x, v = uv.y;
if (u == -1.f) {
return illuminationToInterpolate;
}
// map u,v to texture image
TextureData textureData = material.textureData;
if (textureData.data == nullptr) {
return illuminationToInterpolate;
}
int m = material.textureMap.repeatU;
int c = (int) glm::floor(u * m * textureData.width) % textureData.width;
if (c >= textureData.width) {
c = textureData.width - 1;
}
int n = material.textureMap.repeatV;
int r = (int) glm::floor((1-v) * n * textureData.height) % textureData.height;
if (r >= textureData.height) {
r = textureData.height - 1;
}
RGBA texture = textureData.data[r * textureData.width + c];
// interpolate the texture color with the illumination
float blend = shape.primitive.material.blend;
glm::vec4 blended = blend * (glm::vec4(texture.r, texture.g, texture.b, texture.a) / 255.f)
+ (1.f - blend) * illuminationToInterpolate;
return blended;
}
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