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Frustum class/box intersection testing.
This commit is contained in:
Andrzej Kapolka
parent
8be42bf305
commit
c11b739ad6
2 changed files with 165 additions and 0 deletions
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@ -315,6 +315,134 @@ QDebug& operator<<(QDebug& dbg, const Box& box) {
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return dbg.nospace() << "{type='Box', minimum=" << box.minimum << ", maximum=" << box.maximum << "}";
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}
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AxisExtents::AxisExtents(const glm::vec3& first0, const glm::vec3& first1, const glm::vec3& first2, const glm::vec3& second) :
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axis(glm::cross(first2 - first1, first0 - first1)),
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minimum(glm::dot(first1, axis)),
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maximum(glm::dot(second, axis)) {
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}
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AxisExtents::AxisExtents(const glm::vec3& axis, float minimum, float maximum) :
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axis(axis),
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minimum(minimum),
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maximum(maximum) {
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}
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Frustum::Frustum(const glm::vec3& farTopLeft, const glm::vec3& farTopRight, const glm::vec3& farBottomLeft,
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const glm::vec3& farBottomRight, const glm::vec3& nearTopLeft, const glm::vec3& nearTopRight,
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const glm::vec3& nearBottomLeft, const glm::vec3& nearBottomRight) :
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_bounds(glm::vec3(FLT_MAX, FLT_MAX, FLT_MAX), glm::vec3(-FLT_MAX, -FLT_MAX, -FLT_MAX)) {
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_vertices[0] = farBottomLeft;
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_vertices[1] = farBottomRight;
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_vertices[2] = farTopLeft;
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_vertices[3] = farTopRight;
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_vertices[4] = nearBottomLeft;
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_vertices[5] = nearBottomRight;
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_vertices[6] = nearTopLeft;
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_vertices[7] = nearTopRight;
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for (int i = 0; i < VERTEX_COUNT; i++) {
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_bounds.minimum = glm::min(_bounds.minimum, _vertices[i]);
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_bounds.maximum = glm::max(_bounds.maximum, _vertices[i]);
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}
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// compute the extents for each side
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_sideExtents[0] = AxisExtents(nearBottomLeft, nearTopLeft, nearTopRight, farBottomLeft);
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_sideExtents[1] = AxisExtents(nearBottomLeft, farBottomLeft, farTopLeft, farBottomRight);
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_sideExtents[2] = AxisExtents(nearBottomRight, nearTopRight, farTopRight, farBottomLeft);
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_sideExtents[3] = AxisExtents(nearBottomLeft, nearBottomRight, farBottomRight, farTopLeft);
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_sideExtents[4] = AxisExtents(nearTopLeft, farTopLeft, farTopRight, farBottomRight);
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// the other set of extents are derived from the cross products of the frustum and box edges
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glm::vec3 edges[] = { nearBottomRight - nearBottomLeft, nearTopLeft - nearBottomLeft, farBottomLeft - nearBottomLeft,
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farBottomRight - nearBottomRight, farTopLeft - nearTopLeft, farTopRight - nearTopRight };
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const int AXIS_COUNT = 3;
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for (uint i = 0, extentIndex = 0; i < sizeof(edges) / sizeof(edges[0]); i++) {
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for (int j = 0; j < AXIS_COUNT; j++) {
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glm::vec3 axis;
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axis[j] = 1.0f;
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glm::vec3 crossProduct = glm::cross(edges[i], axis);
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float minimum = FLT_MAX, maximum = -FLT_MAX;
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for (int k = 0; k < VERTEX_COUNT; k++) {
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float projection = glm::dot(crossProduct, _vertices[k]);
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minimum = glm::min(minimum, projection);
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maximum = glm::max(maximum, projection);
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}
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_crossProductExtents[extentIndex++] = AxisExtents(crossProduct, minimum, maximum);
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}
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}
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}
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Frustum::IntersectionType Frustum::getIntersectionType(const Box& box) const {
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// first check the bounds (equivalent to checking frustum vertices against box extents)
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if (!_bounds.intersects(box)) {
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return NO_INTERSECTION;
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}
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// check box vertices against side extents
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bool allInside = true;
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for (int i = 0; i < SIDE_EXTENT_COUNT; i++) {
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const AxisExtents& extents = _sideExtents[i];
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float firstProjection = glm::dot(box.getVertex(0), extents.axis);
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if (firstProjection < extents.minimum) {
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allInside = false;
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for (int j = 1; j < Box::VERTEX_COUNT; j++) {
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if (glm::dot(box.getVertex(j), extents.axis) >= extents.minimum) {
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goto sideContinue;
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}
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}
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return NO_INTERSECTION;
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} else if (firstProjection > extents.maximum) {
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allInside = false;
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for (int j = 1; j < Box::VERTEX_COUNT; j++) {
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if (glm::dot(box.getVertex(j), extents.axis) <= extents.maximum) {
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goto sideContinue;
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}
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}
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return NO_INTERSECTION;
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} else if (allInside) {
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for (int j = 1; j < Box::VERTEX_COUNT; j++) {
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float projection = glm::dot(box.getVertex(j), extents.axis);
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if (projection < extents.minimum || projection > extents.maximum) {
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allInside = false;
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goto sideContinue;
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}
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}
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}
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sideContinue: ;
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}
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if (allInside) {
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return CONTAINS_INTERSECTION;
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}
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// check box vertices against cross product extents
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for (int i = 0; i < CROSS_PRODUCT_EXTENT_COUNT; i++) {
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const AxisExtents& extents = _crossProductExtents[i];
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float firstProjection = glm::dot(box.getVertex(0), extents.axis);
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if (firstProjection < extents.minimum) {
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for (int j = 1; j < Box::VERTEX_COUNT; j++) {
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if (glm::dot(box.getVertex(j), extents.axis) >= extents.minimum) {
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goto crossProductContinue;
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}
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}
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return NO_INTERSECTION;
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} else if (firstProjection > extents.maximum) {
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for (int j = 1; j < Box::VERTEX_COUNT; j++) {
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if (glm::dot(box.getVertex(j), extents.axis) <= extents.maximum) {
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goto crossProductContinue;
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}
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}
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return NO_INTERSECTION;
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}
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crossProductContinue: ;
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}
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return PARTIAL_INTERSECTION;
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}
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QMetaObjectEditor::QMetaObjectEditor(QWidget* parent) : QWidget(parent) {
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QVBoxLayout* layout = new QVBoxLayout();
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layout->setContentsMargins(QMargins());
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@ -65,6 +65,43 @@ Box operator*(const glm::mat4& matrix, const Box& box);
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QDebug& operator<<(QDebug& out, const Box& box);
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/// Represents the extents along an axis.
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class AxisExtents {
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public:
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glm::vec3 axis;
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float minimum;
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float maximum;
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/// Creates a set of extents given three points on the first plane and one on the second.
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AxisExtents(const glm::vec3& first0, const glm::vec3& first1, const glm::vec3& first2, const glm::vec3& second);
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AxisExtents(const glm::vec3& axis = glm::vec3(), float minimum = 0.0f, float maximum = 0.0f);
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};
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/// A simple pyramidal frustum for intersection testing.
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class Frustum {
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public:
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Frustum(const glm::vec3& farTopLeft, const glm::vec3& farTopRight, const glm::vec3& farBottomLeft,
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const glm::vec3& farBottomRight, const glm::vec3& nearTopLeft, const glm::vec3& nearTopRight,
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const glm::vec3& nearBottomLeft, const glm::vec3& nearBottomRight);
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enum IntersectionType { NO_INTERSECTION, PARTIAL_INTERSECTION, CONTAINS_INTERSECTION };
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IntersectionType getIntersectionType(const Box& box) const;
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private:
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static const int VERTEX_COUNT = 8;
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static const int SIDE_EXTENT_COUNT = 5;
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static const int CROSS_PRODUCT_EXTENT_COUNT = 18;
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glm::vec3 _vertices[VERTEX_COUNT];
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Box _bounds;
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AxisExtents _sideExtents[SIDE_EXTENT_COUNT];
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AxisExtents _crossProductExtents[CROSS_PRODUCT_EXTENT_COUNT];
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};
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/// Editor for meta-object values.
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class QMetaObjectEditor : public QWidget {
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Q_OBJECT
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