OpenGL moving vertices with mouse

问题

I am using legacy OpenGL and trying to move vertices around with the mouse. To test whether a vertex is clicked on I loop through all vertices and multiply them by the model and projection matrix before dividing by the w value. This works fine and is shown below:

for (Vertex *vertex : context->getMesh().vertices) {
        QVector4D vert(vertex->xPos, vertex->yPos, vertex->zPos, 1.0f);
        QVector4D transformedVert = projectionMatrix * modelMatrix * vert;
        transformedVert /= transformedVert.w();
        if ((mappedX < (transformedVert.x() + 0.1) && mappedX > (transformedVert.x() - 0.1)) &&
            (mappedY < (transformedVert.y() + 0.1) && mappedY > (transformedVert.y() - 0.1))) {
            std::cout << "SUCCESS" << std::endl;
            vertexPicked = true;
            currentVertex = vertex;
        }
    }

Then when I move the mouse I try to work backwards by first multiplying the current mouse coordinates by the same W value as in the first step and then multiplying by the inverse of the projection and model matrices. This moves the vertex around but not to where the mouse is.

  float mouseX = ((2.0f * event->x()) / width() - 1.0f);
  float mouseY = -((2.0f * event->y()) / height() - 1.0f);
  float x = (modelMatrix.inverted() * projectionMatrix.inverted() *
                (QVector4D(mouseX, mouseY, 1, 1) * (projectionMatrix * modelMatrix * QVector4D(MousePicker::currentVertex->xPos, MousePicker::currentVertex->yPos, MousePicker::currentVertex->zPos, 1)).w())).x();

  MousePicker::currentVertex->xPos = x;

I am currently only trying to change the X coordinate.

来源：https://stackoverflow.com/questions/54462354/opengl-moving-vertices-with-mouse