parabola vs. web and text

libraries/entities/src/TextEntityItem.cpp

@@ -160,7 +160,17 @@ bool TextEntityItem::findDetailedParabolaIntersection(const glm::vec3& origin, c
     glm::vec3 position = getWorldPosition() + rotation * (dimensions * (ENTITY_ITEM_DEFAULT_REGISTRATION_POINT - getRegistrationPoint()));
 
     if (findParabolaRectangleIntersection(origin, velocity, acceleration, rotation, position, xyDimensions, parabolicDistance)) {
-        // get face and surfaceNormal
+        glm::quat inverseRot = glm::inverse(rotation);
+        glm::vec3 localVelocity = inverseRot * velocity;
+        glm::vec3 localAcceleration = inverseRot * acceleration;
+        float localIntersectionVelocityZ = localVelocity.z + localAcceleration.z * parabolicDistance;
+        if (localIntersectionVelocityZ > 0.0f) {
+            face = MIN_Z_FACE;
+            surfaceNormal = rotation * Vectors::FRONT;
+        } else {
+            face = MAX_Z_FACE;
+            surfaceNormal = rotation * -Vectors::FRONT;
+        }
         return true;
     } else {
         return false;

libraries/entities/src/WebEntityItem.cpp

@@ -137,7 +137,17 @@ bool WebEntityItem::findDetailedParabolaIntersection(const glm::vec3& origin, co
     glm::vec3 position = getWorldPosition() + rotation * (dimensions * (ENTITY_ITEM_DEFAULT_REGISTRATION_POINT - getRegistrationPoint()));
 
     if (findParabolaRectangleIntersection(origin, velocity, acceleration, rotation, position, xyDimensions, parabolicDistance)) {
-        // get face and surfaceNormal
+        glm::quat inverseRot = glm::inverse(rotation);
+        glm::vec3 localVelocity = inverseRot * velocity;
+        glm::vec3 localAcceleration = inverseRot * acceleration;
+        float localIntersectionVelocityZ = localVelocity.z + localAcceleration.z * parabolicDistance;
+        if (localIntersectionVelocityZ > 0.0f) {
+            face = MIN_Z_FACE;
+            surfaceNormal = rotation * Vectors::FRONT;
+        } else {
+            face = MAX_Z_FACE;
+            surfaceNormal = rotation * -Vectors::FRONT;
+        }
         return true;
     } else {
         return false;

libraries/shared/src/AABox.cpp

@@ -109,11 +109,6 @@ glm::vec3 AABox::getNearestVertex(const glm::vec3& normal) const {
     return result;
 }
 
-// determines whether a value is within the extents
-static bool isWithin(float value, float corner, float size) {
-    return value >= corner && value <= corner + size;
-}
-
 bool AABox::contains(const Triangle& triangle) const {
     return contains(triangle.v0) && contains(triangle.v1) && contains(triangle.v2);
 }
@@ -308,6 +303,7 @@ bool AABox::findParabolaIntersection(const glm::vec3& origin, const glm::vec3& v
     // Solve the intersection for each face of the cube.  As we go, keep track of the smallest, positive, real distance
     // that is within the bounds of the other two dimensions
     for (int i = 0; i < 3; i++) {
+        // TODO: handle case where a is 0
         a = 0.5f * acceleration[i];
         b = velocity[i];
         if (origin[i] < _corner[i]) {

libraries/shared/src/AACube.cpp

@@ -110,11 +110,6 @@ glm::vec3 AACube::getNearestVertex(const glm::vec3& normal) const {
     return result;
 }
 
-// determines whether a value is within the extents
-static bool isWithin(float value, float corner, float size) {
-    return value >= corner && value <= corner + size;
-}
-
 bool AACube::contains(const glm::vec3& point) const {
     return isWithin(point.x, _corner.x, _scale) &&
         isWithin(point.y, _corner.y, _scale) &&
@@ -304,6 +299,7 @@ bool AACube::findParabolaIntersection(const glm::vec3& origin, const glm::vec3&
     // Solve the intersection for each face of the cube.  As we go, keep track of the smallest, positive, real distance
     // that is within the bounds of the other two dimensions
     for (int i = 0; i < 3; i++) {
+        // TODO: handle case where a is 0
         a = 0.5f * acceleration[i];
         b = velocity[i];
         if (origin[i] < _corner[i]) {

libraries/shared/src/GeometryUtil.cpp

@@ -711,8 +711,42 @@ bool findRayRectangleIntersection(const glm::vec3& origin, const glm::vec3& dire
     return false;
 }
 
+// determines whether a value is within the extents
+bool isWithin(float value, float corner, float size) {
+    return value >= corner && value <= corner + size;
+}
+
+void checkPossibleParabolicIntersectionWithZPlane(float t, float& minDistance,
+    const glm::vec3& origin, const glm::vec3& velocity, const glm::vec3& acceleration, const glm::vec2& corner, const glm::vec2& scale) {
+    if (t < minDistance && t > 0.0f &&
+        isWithin(origin.x + velocity.x * t + 0.5f * acceleration.x * t * t, corner.x, scale.x) &&
+        isWithin(origin.y + velocity.y * t + 0.5f * acceleration.y * t * t, corner.y, scale.y)) {
+        minDistance = t;
+    }
+}
+
 bool findParabolaRectangleIntersection(const glm::vec3& origin, const glm::vec3& velocity, const glm::vec3& acceleration,
     const glm::quat& rotation, const glm::vec3& position, const glm::vec2& dimensions, float& parabolicDistance) {
+    glm::quat inverseRot = glm::inverse(rotation);
+    glm::vec3 localOrigin = inverseRot * (origin - position);
+    glm::vec3 localVelocity = inverseRot * velocity;
+    glm::vec3 localAcceleration = inverseRot * acceleration;
+
+    glm::vec2 localCorner = -0.5f * dimensions;
+
+    float minDistance = FLT_MAX;
+    float a = 0.5f * localAcceleration.z;
+    float b = localVelocity.z;
+    float c = localOrigin.z;
+    std::pair<float, float> possibleDistances = { FLT_MAX, FLT_MAX };
+    if (computeRealQuadraticRoots(a, b, c, possibleDistances)) {
+        checkPossibleParabolicIntersectionWithZPlane(possibleDistances.first, minDistance, localOrigin, localVelocity, localAcceleration, localCorner, dimensions);
+        checkPossibleParabolicIntersectionWithZPlane(possibleDistances.second, minDistance, localOrigin, localVelocity, localAcceleration, localCorner, dimensions);
+    }
+    if (minDistance < FLT_MAX) {
+        parabolicDistance = minDistance;
+        return true;
+    }
     return false;
 }
 

libraries/shared/src/GeometryUtil.h

@@ -183,4 +183,9 @@ void generateBoundryLinesForDop14(const std::vector<float>& dots, const glm::vec
 
 bool computeRealQuadraticRoots(float a, float b, float c, std::pair<float, float>& roots);
 
+bool isWithin(float value, float corner, float size);
+
+void checkPossibleParabolicIntersectionWithZPlane(float t, float& minDistance,
+    const glm::vec3& origin, const glm::vec3& velocity, const glm::vec3& acceleration, const glm::vec2& corner, const glm::vec2& scale);
+
 #endif // hifi_GeometryUtil_h