1 files changed, 115 insertions, 0 deletions
diff --git a/src/illuminate/reflect.cpp b/src/illuminate/reflect.cpp
new file mode 100644
index 0000000..c7fea98
--- /dev/null
+++ b/src/illuminate/reflect.cpp
@@ -0,0 +1,115 @@
+//
+// Created by Michael Foiani on 11/4/23.
+//
+
+#include "raytracer/raytracer.h"
+
+// helper that reflects vectors
+glm::vec3 reflectVector(
+        glm::vec3 incidentDir,
+        glm::vec3 normal)
+{
+    return incidentDir - 2.f * glm::dot(incidentDir, normal) * normal;
+}
+
+glm::vec4 RayTracer::reflect(
+        glm::vec3 intersectionWorld,
+        glm::vec3 normalWorld,
+        glm::vec3 incidentDir,
+        const RenderShapeData &shape,
+        const RayTraceScene &scene,
+        int depth)
+{
+    auto material = shape.primitive.material;
+    // check if the material is reflective
+    if (material.cReflective == glm::vec4(0.f))
+    {
+        return glm::vec4(0.f);
+    }
+    auto reflectedDir = reflectVector(incidentDir, normalWorld);
+
+    // shoot a ray from the intersection point in the reflected direction
+    auto reflectColors = getPixelFromRay(glm::vec4(intersectionWorld + .001f * reflectedDir, 1.f), glm::vec4(reflectedDir, 0.f), scene, depth + 1);
+    return scene.getGlobalData().ks * material.cReflective * reflectColors;
+}
+
+// EXTRA CREDIT -> refracting
+
+// TRUE REFRACTING
+// get the reflection coefficient from fresnel's equations
+bool REAL_REFRACTING = false;
+float fresnels(
+        float currentMediumIor,
+        float otherMediumIor,
+        float cosAngleIncident,
+        float cosAngleTransmitted)
+{
+    float rPerp = (currentMediumIor * cosAngleIncident - otherMediumIor * cosAngleTransmitted) /
+                  (currentMediumIor * cosAngleIncident + otherMediumIor * cosAngleTransmitted);
+    rPerp *= rPerp;
+    float rPara = (otherMediumIor * cosAngleIncident - currentMediumIor * cosAngleTransmitted) /
+                  (otherMediumIor * cosAngleIncident + currentMediumIor * cosAngleTransmitted);
+    rPara *= rPara;
+    return (rPerp + rPara) / 2.f;
+}
+
+// Your refracting
+glm::vec4 RayTracer::refract(
+        glm::vec3  intersectionWorld,
+        glm::vec3  normalWorld,
+        glm::vec3  incidentDir,
+        const RenderShapeData& shape,
+        const RayTraceScene &scene,
+        int depth
+)
+{
+    auto material = shape.primitive.material;
+    // check if the material is transparent
+    if (material.cTransparent == glm::vec4(0.f))
+    {
+        return glm::vec4(0.f);
+    }
+
+    // apply snells law to find the sin of refracted angle (squared)
+    incidentDir = glm::normalize(incidentDir);
+    float cosAngleIncident = glm::dot(incidentDir, normalWorld);
+    float currentMediumIor = mediumIor;
+    float otherMediumIor = material.ior;
+
+    if (cosAngleIncident < 0)
+    {
+        // outside the object
+        cosAngleIncident = -cosAngleIncident;
+    }
+    else
+    {
+        // inside the object, invert the normal and swap the Iors
+        normalWorld = -normalWorld;
+        std::swap(currentMediumIor, otherMediumIor);
+    }
+
+    float iorRatio = currentMediumIor / otherMediumIor;
+    float sinAngleTransmittedSquared = iorRatio * iorRatio * (1 - cosAngleIncident * cosAngleIncident);
+    if (sinAngleTransmittedSquared > 1.f) // total internal reflection, not considered
+    {
+        return glm::vec4(0.f);
+    }
+
+    auto cosAngleTransmitted = glm::sqrt(1 - sinAngleTransmittedSquared);
+
+    // compute refracted ray according to snell's law
+    auto refractedDir = glm::normalize(
+            incidentDir * iorRatio
+            + (iorRatio * cosAngleIncident - cosAngleTransmitted) * normalWorld);
+
+    // send a ray in the refracted direction to get the colors
+    auto refractedColors = getPixelFromRay(
+            glm::vec4(intersectionWorld + .001f * refractedDir, 1.f),
+            glm::vec4(refractedDir, 0.f),
+            scene,
+            depth + 1);
+
+    float fresnel = fresnels(currentMediumIor, otherMediumIor, cosAngleIncident, cosAngleTransmitted);
+    auto color = scene.getGlobalData().kt * material.cTransparent * refractedColors * (1 - fresnel);
+    return color;
+}
+\ No newline at end of file