new directory for 4d vector math

1 files changed, 30 insertions, 0 deletions

diff --git a/src/4dvecops/vectoroperations.cpp b/src/4dvecops/vectoroperations.cpp
new file mode 100644
index 0000000..d41dad3
--- /dev/null
+++ b/src/4dvecops/vectoroperations.cpp
@@ -0,0 +1,30 @@
+#include "raytracer/raytracer.h"
+
+// vector operations on 4d vectors,
+// reference: https://hollasch.github.io/ray4/Four-Space_Visualization_of_4D_Objects.html#chapter5
+
+glm::vec4 cross4(
+        glm::vec4 u,
+        glm::vec4 v,
+        glm::vec4 w) {
+    float a = (v[0] * w[1]) - (v[1] * w[0]);
+    float b = (v[0] * w[2]) - (v[2] * w[0]);
+    float c = (v[0] * w[3]) - (v[3] * w[0]);
+    float d = (v[1] * w[2]) - (v[2] * w[1]);
+    float e = (v[1] * w[3]) - (v[3] * w[1]);
+    float f = (v[2] * w[3]) - (v[3] * w[2]);
+
+    glm::vec4 result;
+    result[0] = (u[1] * f) - (u[2] * e) + (u[3] * d);
+    result[1] = -(u[0] * f) + (u[2] * c) - (u[3] * b);
+    result[2] = (u[0] * e) - (u[1] * c) + (u[3] * a);
+    result[3] = -(u[0] * d) + (u[1] * b) - (u[2] * a);
+
+    return result;
+}
+
+glm::vec4 dot4(
+        glm::vec4 u,
+        glm::vec4 v) {
+    return {u[0] * v[0], u[1] * v[1], u[2] * v[2], u[3] * v[3]};
+}
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