Function GetAxesParameters

implot3d.cpp:1228–1326

Function to get axes parameters which can then be used later down the line

// Function to get axes parameters which can then be used later down the line
void GetAxesParameters(const ImPlot3DPlot& plot, bool* active_faces, ImVec2* corners_pix, ImPlot3DPoint* corners, int& plane_2d,
                       int axis_corners[3][2]) {
    // Get plot parameters
    const ImPlot3DQuat& rotation = plot.Rotation;
    ImPlot3DPoint range_min = plot.RangeMin();
    ImPlot3DPoint range_max = plot.RangeMax();

    // Compute active faces
    ComputeActiveFaces(active_faces, rotation, plot.Axes, &plane_2d);
    bool is_2d = plane_2d != -1;

    // Compute box corners in plot space
    ComputeBoxCorners(corners, range_min, range_max);

    // Compute box corners in pixel space
    ComputeBoxCornersPix(plot, corners_pix, corners);

    // Compute axes start and end corners (given current rotation)
    if (is_2d) {
        int face = plane_2d + 3 * active_faces[plane_2d]; // Face of the 2D plot
        int common_edges[2] = {-1, -1};                   // Edges shared by the 3 faces

        // Find the common edges between the 3 faces
        for (int i = 0; i < 4; i++) {
            int edge = face_edges[face][i];
            for (int j = 0; j < 2; j++) {
                int axis = (plane_2d + 1 + j) % 3;
                int face_idx = axis + active_faces[axis] * 3;
                for (int k = 0; k < 4; k++) {
                    if (face_edges[face_idx][k] == edge) {
                        common_edges[j] = edge;
                        break;
                    }
                }
            }
        }

        // Get corners from 2 edges (origin is the corner in common)
        int origin_corner = -1;
        int x_corner = -1;
        int y_corner = -1;
        for (int i = 0; i < 2; i++)
            for (int j = 0; j < 2; j++)
                if (edges[common_edges[0]][i] == edges[common_edges[1]][j]) {
                    origin_corner = edges[common_edges[0]][i];
                    x_corner = edges[common_edges[0]][!i];
                    y_corner = edges[common_edges[1]][!j];
                }

        // Swap x and y if they are flipped
        ImVec2 x_vec = corners_pix[x_corner] - corners_pix[origin_corner];
        ImVec2 y_vec = corners_pix[y_corner] - corners_pix[origin_corner];
        if (y_vec.x > x_vec.x)
            ImSwap(x_corner, y_corner);

        // Check which 3d axis the 2d axis refers to
        ImPlot3DPoint origin_3d = corners[origin_corner];
        ImPlot3DPoint x_3d = (corners[x_corner] - origin_3d).Normalized();