1 files changed, 82 insertions, 0 deletions
diff --git a/dev/MinGfx/src/gfxmath.cc b/dev/MinGfx/src/gfxmath.cc
new file mode 100644
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--- /dev/null
+++ b/dev/MinGfx/src/gfxmath.cc
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+/*
+ Copyright (c) 2017,2018 Regents of the University of Minnesota.
+ All Rights Reserved.
+ See corresponding header file for details.
+ */
+
+#include "gfxmath.h"
+
+#define _USE_MATH_DEFINES
+#include <math.h>
+#include <algorithm>
+
+#include "ray.h"
+
+
+namespace mingfx {
+    
+const float GfxMath::PI = 3.14159265359f;
+const float GfxMath::TWO_PI = 6.28318530718f;
+const float GfxMath::HALF_PI = 1.57079632679f;
+
+
+float GfxMath::Clamp(float x, float a, float b) {
+    return std::min(std::max(x, a), b);
+}    
+
+float GfxMath::ToRadians(float degrees) {
+    return degrees * GfxMath::PI / 180.0f;
+}
+
+float GfxMath::ToDegrees(float radians) {
+    return radians * 180.0f / GfxMath::PI;
+}
+
+Vector3 GfxMath::ToRadians(Vector3 degrees) {
+    return Vector3(ToRadians(degrees[0]), ToRadians(degrees[1]), ToRadians(degrees[2]));
+}
+
+Vector3 GfxMath::ToDegrees(Vector3 radians) {
+    return Vector3(ToDegrees(radians[0]), ToDegrees(radians[1]), ToDegrees(radians[2]));
+}
+    
+float GfxMath::Lerp(float a, float b, float alpha) {
+    return (1.0f-alpha)*a + alpha*b;
+}
+    
+int GfxMath::iLerp(int a, int b, float alpha) {
+    return (int)std::round((1.0f-alpha)*(float)a + alpha*(float)b);
+}
+    
+Point3 GfxMath::ScreenToNearPlane(const Matrix4 &V, const Matrix4 &P, const Point2 &ndcPoint) {
+    Matrix4 filmPtToWorld = (P*V).Inverse();
+    return filmPtToWorld * Point3(ndcPoint[0], ndcPoint[1], -1.0);
+}
+    
+    
+Point3 GfxMath::ScreenToWorld(const Matrix4 &V, const Matrix4 &P, const Point2 &ndcPoint, float zValue) {
+    Matrix4 filmPtToWorld = (P*V).Inverse();
+    float zneg1topos1 = zValue*2.0f - 1.0f;
+    return filmPtToWorld * Point3(ndcPoint[0], ndcPoint[1], zneg1topos1);
+}
+
+    
+Point3 GfxMath::ScreenToDepthPlane(const Matrix4 &V, const Matrix4 &P, const Point2 &ndcPoint, float planeDepth) {
+    Point3 pNear = ScreenToNearPlane(V, P, ndcPoint);
+    
+    Matrix4 camMat = V.Inverse();
+    Point3 eye = camMat.ColumnToPoint3(3);
+    Vector3 look = -camMat.ColumnToVector3(2);
+    
+    Ray r(eye, pNear - eye);
+    
+    Point3 p3D;
+    float t;
+    if (!r.IntersectPlane(eye + planeDepth*look, -look, &t, &p3D)) {
+        std::cerr << "filmplane2D_to_plane3D() error -- no intersection found!" << std::endl;
+    }
+    return p3D;
+}
+    
+    
+} // end namespace