module fortplot_3d_axes !! 3D axes rendering module for projecting 3D axis frames to 2D !! !! Provides clean, efficient routines for rendering 3D coordinate frames !! with proper tick marks and labels aligned to visible axis segments. use, intrinsic :: iso_fortran_env, only: wp => real64 use fortplot_context, only: plot_context use fortplot_tick_calculation, only: find_nice_tick_locations, & format_tick_value_consistent, & determine_decimal_places_from_step use fortplot_projection, only: project_3d_to_2d, get_default_view_angles implicit none private public :: draw_3d_axes ! Constants for 3D visualization - percentage of axis length for true consistency integer, parameter :: MAX_TICKS_PER_AXIS = 10 ! Constants for visually consistent tick appearance (percentages of rendered axis length) real(wp), parameter :: VISUAL_TICK_PERCENT = 0.04_wp ! Preferred tick length as 4% of rendered axis length real(wp), parameter :: VISUAL_PADDING_PERCENT = 0.06_wp ! Preferred label padding as 6% of rendered axis length real(wp), parameter :: VISUAL_Z_EXTRA_PERCENT = 0.03_wp ! Preferred extra Z-axis spacing as 3% of rendered axis length ! Hard clamps to avoid extremes (fractions of edge length) real(wp), parameter :: VISUAL_TICK_MIN = 0.01_wp real(wp), parameter :: VISUAL_TICK_MAX = 0.06_wp real(wp), parameter :: VISUAL_PADDING_MIN = 0.03_wp real(wp), parameter :: VISUAL_PADDING_MAX = 0.12_wp real(wp), parameter :: EPSILON = 1.0e-12_wp ! Numerical epsilon for divisions ! Axis identification integer, parameter :: X_AXIS = 1, Y_AXIS = 2, Z_AXIS = 3 ! Corner indices for readability integer, parameter :: & CORNER_MIN_MIN_MIN = 1, & ! (x_min, y_min, z_min) CORNER_MAX_MIN_MIN = 2, & ! (x_max, y_min, z_min) CORNER_MAX_MAX_MIN = 3, & ! (x_max, y_max, z_min) CORNER_MIN_MAX_MIN = 4, & ! (x_min, y_max, z_min) CORNER_MIN_MIN_MAX = 5, & ! (x_min, y_min, z_max) CORNER_MAX_MIN_MAX = 6, & ! (x_max, y_min, z_max) CORNER_MAX_MAX_MAX = 7, & ! (x_max, y_max, z_max) CORNER_MIN_MAX_MAX = 8 ! (x_min, y_max, z_max) contains subroutine draw_3d_axes(ctx, x_min, x_max, y_min, y_max, z_min, z_max) !! Draw complete 3D axes frame with ticks and labels !! !! This is the main entry point that handles all 3D axis rendering: !! - Projects 3D bounding box to 2D coordinates !! - Draws visible axis segments !! - Places tick marks and labels at appropriate positions class(plot_context), intent(inout) :: ctx real(wp), intent(in) :: x_min, x_max, y_min, y_max, z_min, z_max real(wp) :: corners_3d(3,8), corners_2d(2,8) real(wp) :: azim, elev, dist ! Validate input ranges if (x_max <= x_min .or. y_max <= y_min .or. z_max <= z_min) return ! Set up 3D projection call get_default_view_angles(azim, elev, dist) call create_unit_cube(corners_3d) call project_to_2d(corners_3d, azim, elev, dist, corners_2d) call scale_to_data_range(corners_2d, x_min, x_max, y_min, y_max) ! Draw the three visible axis segments call draw_axis_lines(ctx, corners_2d) ! Draw ticks and labels on each axis call draw_all_axis_ticks(ctx, corners_2d, x_min, x_max, y_min, y_max, z_min, z_max) end subroutine draw_3d_axes subroutine create_unit_cube(corners_3d) !! Create unit cube vertices in normalized [0,1]³ space real(wp), intent(out) :: corners_3d(3,8) ! Define all 8 corners of unit cube systematically corners_3d(:,CORNER_MIN_MIN_MIN) = [0.0_wp, 0.0_wp, 0.0_wp] corners_3d(:,CORNER_MAX_MIN_MIN) = [1.0_wp, 0.0_wp, 0.0_wp] corners_3d(:,CORNER_MAX_MAX_MIN) = [1.0_wp, 1.0_wp, 0.0_wp] corners_3d(:,CORNER_MIN_MAX_MIN) = [0.0_wp, 1.0_wp, 0.0_wp] corners_3d(:,CORNER_MIN_MIN_MAX) = [0.0_wp, 0.0_wp, 1.0_wp] corners_3d(:,CORNER_MAX_MIN_MAX) = [1.0_wp, 0.0_wp, 1.0_wp] corners_3d(:,CORNER_MAX_MAX_MAX) = [1.0_wp, 1.0_wp, 1.0_wp] corners_3d(:,CORNER_MIN_MAX_MAX) = [0.0_wp, 1.0_wp, 1.0_wp] end subroutine create_unit_cube subroutine project_to_2d(corners_3d, azim, elev, dist, corners_2d) !! Project 3D corners to 2D using standard viewing transformation real(wp), intent(in) :: corners_3d(3,8), azim, elev, dist real(wp), intent(out) :: corners_2d(2,8) real(wp) :: x3d(8), y3d(8), z3d(8), x2d(8), y2d(8) ! Extract coordinates for projection x3d = corners_3d(1,:) y3d = corners_3d(2,:) z3d = corners_3d(3,:) call project_3d_to_2d(x3d, y3d, z3d, azim, elev, dist, x2d, y2d) corners_2d(1,:) = x2d corners_2d(2,:) = y2d end subroutine project_to_2d subroutine scale_to_data_range(corners_2d, x_min, x_max, y_min, y_max) !! Scale projected coordinates to actual data ranges real(wp), intent(inout) :: corners_2d(2,8) real(wp), intent(in) :: x_min, x_max, y_min, y_max real(wp) :: proj_bounds(4), data_ranges(2) integer :: i ! Find projection bounds proj_bounds(1) = minval(corners_2d(1,:)) ! proj_x_min proj_bounds(2) = maxval(corners_2d(1,:)) ! proj_x_max proj_bounds(3) = minval(corners_2d(2,:)) ! proj_y_min proj_bounds(4) = maxval(corners_2d(2,:)) ! proj_y_max ! Calculate scaling factors data_ranges(1) = max(EPSILON, x_max - x_min) data_ranges(2) = max(EPSILON, y_max - y_min) ! Scale all corners do i = 1, 8 corners_2d(1,i) = x_min + (corners_2d(1,i) - proj_bounds(1)) / & max(EPSILON, proj_bounds(2) - proj_bounds(1)) * data_ranges(1) corners_2d(2,i) = y_min + (corners_2d(2,i) - proj_bounds(3)) / & max(EPSILON, proj_bounds(4) - proj_bounds(3)) * data_ranges(2) end do end subroutine scale_to_data_range subroutine draw_axis_lines(ctx, corners_2d) !! Draw the three visible axis lines forming the 3D coordinate frame class(plot_context), intent(inout) :: ctx real(wp), intent(in) :: corners_2d(2,8) ! X-axis: front bottom edge call ctx%line(corners_2d(1,CORNER_MIN_MIN_MIN), corners_2d(2,CORNER_MIN_MIN_MIN), & corners_2d(1,CORNER_MAX_MIN_MIN), corners_2d(2,CORNER_MAX_MIN_MIN)) ! Y-axis: front right edge call ctx%line(corners_2d(1,CORNER_MAX_MIN_MIN), corners_2d(2,CORNER_MAX_MIN_MIN), & corners_2d(1,CORNER_MAX_MAX_MIN), corners_2d(2,CORNER_MAX_MAX_MIN)) ! Z-axis: front left vertical call ctx%line(corners_2d(1,CORNER_MIN_MIN_MIN), corners_2d(2,CORNER_MIN_MIN_MIN), & corners_2d(1,CORNER_MIN_MIN_MAX), corners_2d(2,CORNER_MIN_MIN_MAX)) end subroutine draw_axis_lines subroutine draw_all_axis_ticks(ctx, corners_2d, x_min, x_max, y_min, y_max, z_min, z_max) !! Draw ticks and labels for all three axes class(plot_context), intent(inout) :: ctx real(wp), intent(in) :: corners_2d(2,8) real(wp), intent(in) :: x_min, x_max, y_min, y_max, z_min, z_max ! Draw each axis independently using the same pattern call draw_single_axis_ticks(ctx, corners_2d, X_AXIS, x_min, x_max, x_min, x_max, y_min, y_max, z_min, z_max) call draw_single_axis_ticks(ctx, corners_2d, Y_AXIS, y_min, y_max, x_min, x_max, y_min, y_max, z_min, z_max) call draw_single_axis_ticks(ctx, corners_2d, Z_AXIS, z_min, z_max, x_min, x_max, y_min, y_max, z_min, z_max) end subroutine draw_all_axis_ticks subroutine draw_single_axis_ticks(ctx, corners_2d, axis_id, axis_min, axis_max, x_min, x_max, y_min, y_max, z_min, z_max) !! Draw ticks and labels for a single axis class(plot_context), intent(inout) :: ctx real(wp), intent(in) :: corners_2d(2,8) integer, intent(in) :: axis_id real(wp), intent(in) :: axis_min, axis_max, x_min, x_max, y_min, y_max, z_min, z_max real(wp) :: tick_values(MAX_TICKS_PER_AXIS), step_size real(wp) :: nice_min, nice_max integer :: n_ticks, decimals, corner1, corner2 ! Get nice tick locations call find_nice_tick_locations(axis_min, axis_max, 5, nice_min, nice_max, & step_size, tick_values, n_ticks) decimals = determine_decimal_places_from_step(step_size) ! Determine corner indices for this axis select case (axis_id) case (X_AXIS) corner1 = CORNER_MIN_MIN_MIN; corner2 = CORNER_MAX_MIN_MIN case (Y_AXIS) corner1 = CORNER_MAX_MIN_MIN; corner2 = CORNER_MAX_MAX_MIN case (Z_AXIS) corner1 = CORNER_MIN_MIN_MIN; corner2 = CORNER_MIN_MIN_MAX end select call draw_ticks_on_edge(ctx, corners_2d, corner1, corner2, tick_values, n_ticks, & axis_min, axis_max, x_min, x_max, y_min, y_max, z_min, z_max, decimals, axis_id) end subroutine draw_single_axis_ticks subroutine draw_ticks_on_edge(ctx, corners_2d, corner1, corner2, tick_values, n_ticks, & axis_min, axis_max, x_min, x_max, y_min, y_max, z_min, z_max, decimals, axis_id) !! Draw tick marks and labels along a specific edge with visually consistent lengths class(plot_context), intent(inout) :: ctx real(wp), intent(in) :: corners_2d(2,8) integer, intent(in) :: corner1, corner2, n_ticks, decimals, axis_id real(wp), contiguous, intent(in) :: tick_values(:) real(wp), intent(in) :: axis_min, axis_max real(wp), intent(in) :: x_min, x_max, y_min, y_max, z_min, z_max real(wp) :: tick_pos(2), tick_end(2), label_pos(2) real(wp) :: range_factor real(wp) :: edge_vec(2), edge_len, normal_vec(2), edge_mid(2), plot_center(2) real(wp) :: width_scale, height_scale, canvas_w_px, canvas_h_px real(wp) :: tick_px, pad_px, extra_px real(wp) :: tol integer :: i, j ! Buffers for two-pass layout real(wp) :: cand_label_pos(2, MAX_TICKS_PER_AXIS) logical :: cand_valid(MAX_TICKS_PER_AXIS) logical :: cand_endpoint(MAX_TICKS_PER_AXIS) character(len=32) :: cand_text(MAX_TICKS_PER_AXIS) integer :: order(MAX_TICKS_PER_AXIS) ! Phase 1: compute edge geometry call compute_edge_geometry(ctx, corners_2d, corner1, corner2, axis_id, & x_min, x_max, y_min, y_max, & edge_vec, edge_len, normal_vec, edge_mid, plot_center, & width_scale, height_scale, canvas_w_px, canvas_h_px, & tick_px, pad_px, extra_px) if (edge_len <= EPSILON) return ! Phase 2: collect tick candidates tol = 1.0e-9_wp * max(1.0_wp, abs(axis_max - axis_min)) do i = 1, n_ticks if (tick_values(i) < axis_min .or. tick_values(i) > axis_max) cycle range_factor = (tick_values(i) - axis_min) / max(EPSILON, axis_max - axis_min) tick_pos(1) = corners_2d(1,corner1) + range_factor * (corners_2d(1,corner2) - corners_2d(1,corner1)) tick_pos(2) = corners_2d(2,corner1) + range_factor * (corners_2d(2,corner2) - corners_2d(2,corner1)) call compute_tick_positions(axis_id, tick_pos, normal_vec, tick_px, pad_px, extra_px, & width_scale, height_scale, tick_end, label_pos) call ctx%line(tick_pos(1), tick_pos(2), tick_end(1), tick_end(2)) cand_valid(i) = .true. cand_label_pos(:, i) = label_pos cand_text(i) = format_tick_value_consistent(tick_values(i), decimals) cand_endpoint(i) = (abs(tick_values(i) - axis_min) <= tol) .or. & (abs(tick_values(i) - axis_max) <= tol) if (axis_id == X_AXIS .and. i == n_ticks) cand_valid(i) = .false. if (axis_id == Y_AXIS .and. i == 1) cand_valid(i) = .false. end do ! Phase 3: order candidates (endpoints first) call order_tick_candidates(n_ticks, cand_valid, cand_endpoint, order, j) ! Phase 4: greedy selection with spacing constraint call select_and_draw_labels(j, order, cand_valid, cand_label_pos, cand_text, & width_scale, height_scale, ctx) end subroutine draw_ticks_on_edge subroutine compute_edge_geometry(ctx, corners_2d, corner1, corner2, axis_id, & x_min, x_max, y_min, y_max, & edge_vec, edge_len, normal_vec, edge_mid, plot_center, & width_scale, height_scale, canvas_w_px, canvas_h_px, & tick_px, pad_px, extra_px) !! Compute edge direction, normal, and pixel-scale dimensions class(plot_context), intent(in) :: ctx real(wp), intent(in) :: corners_2d(2,8) integer, intent(in) :: corner1, corner2, axis_id real(wp), intent(in) :: x_min, x_max, y_min, y_max real(wp), intent(out) :: edge_vec(2), edge_len real(wp), intent(out) :: normal_vec(2), edge_mid(2), plot_center(2) real(wp), intent(out) :: width_scale, height_scale, canvas_w_px, canvas_h_px real(wp), intent(out) :: tick_px, pad_px, extra_px edge_vec(1) = corners_2d(1,corner2) - corners_2d(1,corner1) edge_vec(2) = corners_2d(2,corner2) - corners_2d(2,corner1) edge_len = sqrt(edge_vec(1)**2 + edge_vec(2)**2) normal_vec = [ -edge_vec(2)/edge_len, edge_vec(1)/edge_len ] edge_mid = 0.5_wp * [ corners_2d(1,corner1)+corners_2d(1,corner2), & corners_2d(2,corner1)+corners_2d(2,corner2) ] plot_center = [ sum(corners_2d(1,:))/8.0_wp, sum(corners_2d(2,:))/8.0_wp ] if ( (normal_vec(1)*(edge_mid(1)-plot_center(1)) + normal_vec(2)*(edge_mid(2)-plot_center(2))) < 0.0_wp ) then normal_vec = -normal_vec end if width_scale = ctx%get_width_scale() height_scale = ctx%get_height_scale() canvas_w_px = width_scale * (x_max - x_min) canvas_h_px = height_scale * (y_max - y_min) tick_px = max(4.0_wp, min(12.0_wp, VISUAL_TICK_PERCENT * min(canvas_w_px, canvas_h_px))) pad_px = max(6.0_wp, min(24.0_wp, VISUAL_PADDING_PERCENT * min(canvas_w_px, canvas_h_px))) extra_px = merge(max(0.0_wp, VISUAL_Z_EXTRA_PERCENT) * min(canvas_w_px, canvas_h_px), 0.0_wp, axis_id == Z_AXIS) end subroutine compute_edge_geometry subroutine compute_tick_positions(axis_id, tick_pos, normal_vec, tick_px, pad_px, extra_px, & width_scale, height_scale, tick_end, label_pos) !! Compute tick end point and label position for a single tick integer, intent(in) :: axis_id real(wp), intent(in) :: tick_pos(2), normal_vec(2) real(wp), intent(in) :: tick_px, pad_px, extra_px real(wp), intent(in) :: width_scale, height_scale real(wp), intent(out) :: tick_end(2), label_pos(2) if (axis_id == Z_AXIS) then tick_end(1) = tick_pos(1) + sign(1.0_wp, normal_vec(1)) * (tick_px / max(EPSILON, width_scale)) tick_end(2) = tick_pos(2) label_pos(1) = tick_end(1) + sign(1.0_wp, normal_vec(1)) * ((pad_px + extra_px) / max(EPSILON, width_scale)) label_pos(2) = tick_pos(2) else tick_end(1) = tick_pos(1) tick_end(2) = tick_pos(2) + sign(1.0_wp, normal_vec(2)) * (tick_px / max(EPSILON, height_scale)) label_pos(1) = tick_pos(1) label_pos(2) = tick_end(2) + sign(1.0_wp, normal_vec(2)) * ((pad_px + extra_px) / max(EPSILON, height_scale)) end if end subroutine compute_tick_positions subroutine order_tick_candidates(n_ticks, cand_valid, cand_endpoint, order, n_ordered) !! Order tick candidates: endpoints first, then others integer, intent(in) :: n_ticks logical, intent(in) :: cand_valid(:), cand_endpoint(:) integer, intent(out) :: order(:) integer, intent(out) :: n_ordered integer :: i, j j = 0 do i = 1, n_ticks if (cand_valid(i) .and. cand_endpoint(i)) then j = j + 1 order(j) = i end if end do do i = 1, n_ticks if (cand_valid(i) .and. .not. cand_endpoint(i)) then j = j + 1 order(j) = i end if end do n_ordered = j end subroutine order_tick_candidates subroutine select_and_draw_labels(n_ordered, order, cand_valid, cand_label_pos, cand_text, & width_scale, height_scale, ctx) !! Greedy label selection with pixel-spacing constraint integer, intent(in) :: n_ordered integer, intent(in) :: order(MAX_TICKS_PER_AXIS) logical, intent(in) :: cand_valid(MAX_TICKS_PER_AXIS) real(wp), intent(in) :: cand_label_pos(2, MAX_TICKS_PER_AXIS) character(len=32), intent(in) :: cand_text(MAX_TICKS_PER_AXIS) real(wp), intent(in) :: width_scale, height_scale class(plot_context), intent(inout) :: ctx real(wp) :: last_drawn_px(2) logical :: have_last real(wp) :: dxp, dyp, dist_px integer :: i have_last = .false. do i = 1, n_ordered if (.not. cand_valid(order(i))) cycle if (.not. have_last) then call ctx%text(cand_label_pos(1,order(i)), cand_label_pos(2,order(i)), & trim(adjustl(cand_text(order(i))))) last_drawn_px = [ cand_label_pos(1,order(i))*width_scale, & cand_label_pos(2,order(i))*height_scale ] have_last = .true. else dxp = cand_label_pos(1,order(i))*width_scale - last_drawn_px(1) dyp = cand_label_pos(2,order(i))*height_scale - last_drawn_px(2) dist_px = sqrt(dxp*dxp + dyp*dyp) if (dist_px >= 22.0_wp) then call ctx%text(cand_label_pos(1,order(i)), cand_label_pos(2,order(i)), & trim(adjustl(cand_text(order(i))))) last_drawn_px = [ cand_label_pos(1,order(i))*width_scale, & cand_label_pos(2,order(i))*height_scale ] end if end if end do end subroutine select_and_draw_labels ! ...existing code... end module fortplot_3d_axes