// -----------------------------------------------------------------------
// Modular LED Matrix X-Brace Backplate with Flush Snaps
// -----------------------------------------------------------------------
// NATIVE LANDSCAPE LAYOUT (3 columns x 2 rows)
// Select which tile to generate:
// 1 = Top Left      |  2 = Top Mid      |  3 = Top Right
// 4 = Bottom Left   |  5 = Bottom Mid   |  6 = Bottom Right
part = 1; // [1:6]

// --- Matrix Parameters ---
cellsX = 16;
cellsY = 16;
pitch = 10;

// Flat 1.6mm Z-plane for fast FDM printing
thickness = 1.6; 
brace_width = 15;
hub_diameter = 40; // Added central hub for structural integrity

// --- Frame Parameters ---
borderWidth = 10;
holeRad = 2;
inner_rim = 8; // Solid rim on interior seams for the snaps to anchor into

// --- Logic ---
hasLeft   = (part == 1 || part == 4) ? 1 : 0;
hasRight  = (part == 3 || part == 6) ? 1 : 0;
hasTop    = (part == 1 || part == 2 || part == 3) ? 1 : 0;
hasBottom = (part == 4 || part == 5 || part == 6) ? 1 : 0;

gridWidth = cellsX * pitch;
gridHeight = cellsY * pitch;

leftOffset = hasLeft * borderWidth;
bottomOffset = hasBottom * borderWidth;

totalWidth = gridWidth + (hasLeft * borderWidth) + (hasRight * borderWidth);
totalHeight = gridHeight + (hasTop * borderWidth) + (hasBottom * borderWidth);

left_rim   = hasLeft ? borderWidth : inner_rim;
right_rim  = hasRight ? borderWidth : inner_rim;
top_rim    = hasTop ? borderWidth : inner_rim;
bottom_rim = hasBottom ? borderWidth : inner_rim;

$fn = 32;

// --- Flush Puzzle Snaps (XY Plane) ---
module puzzle_tab_x() {
    // Points out to the right
    translate([0, -3, 0]) cube([3, 6, thickness]); 
    translate([3, 0, 0]) cylinder(r=4, h=thickness); 
}
module puzzle_slot_x() {
    // Cuts inwards from the left
    translate([-0.1, -3.2, -1]) cube([3.2, 6.4, thickness+2]);
    translate([3, 0, -1]) cylinder(r=4.2, h=thickness+2);
}
module puzzle_tab_y() {
    // Points downwards
    rotate([0, 0, -90]) puzzle_tab_x();
}
module puzzle_slot_y() {
    // Cuts downwards from the top
    rotate([0, 0, -90]) puzzle_slot_x();
}

difference() {
    union() {
        // Main solid frame with hollowed center
        difference() {
            cube([totalWidth, totalHeight, thickness], center=false);
            
            // Punch out the dead space
            translate([left_rim, bottom_rim, -1])
            cube([
                totalWidth - left_rim - right_rim, 
                totalHeight - top_rim - bottom_rim, 
                thickness + 2
            ]);
        }
        
        // Internal X-Braces with Central Hub
        intersection() {
            cube([totalWidth, totalHeight, thickness]);
            union() {
                // Diagonal /
                hull() {
                    translate([left_rim, bottom_rim, 0]) 
                        cylinder(d=brace_width, h=thickness);
                    translate([totalWidth - right_rim, totalHeight - top_rim, 0]) 
                        cylinder(d=brace_width, h=thickness);
                }
                // Diagonal \
                hull() {
                    translate([totalWidth - right_rim, bottom_rim, 0]) 
                        cylinder(d=brace_width, h=thickness);
                    translate([left_rim, totalHeight - top_rim, 0]) 
                        cylinder(d=brace_width, h=thickness);
                }
                // Central Hub
                translate([totalWidth/2, totalHeight/2, 0])
                    cylinder(d=hub_diameter, h=thickness);
            }
        }
        
        // Add Male Puzzle Tabs on internal mating edges
        if (!hasRight) {
            translate([totalWidth, totalHeight/3, 0]) puzzle_tab_x();
            translate([totalWidth, 2*totalHeight/3, 0]) puzzle_tab_x();
        }
        if (!hasBottom) {
            translate([totalWidth/3, 0, 0]) puzzle_tab_y();
            translate([2*totalWidth/3, 0, 0]) puzzle_tab_y();
        }
    }
    
    // Cut Female Puzzle Slots on internal mating edges
    if (!hasLeft) {
        translate([0, totalHeight/3, 0]) puzzle_slot_x();
        translate([0, 2*totalHeight/3, 0]) puzzle_slot_x();
    }
    if (!hasTop) {
        translate([totalWidth/3, totalHeight, 0]) puzzle_slot_y();
        translate([2*totalWidth/3, totalHeight, 0]) puzzle_slot_y();
    }

    // --- Mounting Holes ---
    // Left Border
    if (hasLeft) { 
        for (i = [1 : 3]) { 
            translate([borderWidth / 2, bottomOffset + (i * gridHeight/4), -1]) 
            cylinder(h=thickness + 2, r=holeRad); 
        } 
    } 
    
    // Right Border
    if (hasRight) { 
        for (i = [1 : 3]) { 
            translate([totalWidth - (borderWidth / 2), bottomOffset + (i * gridHeight/4), -1]) 
            cylinder(h=thickness + 2, r=holeRad); 
        } 
    } 

    // Top Border
    if (hasTop) { 
        for (i = [1 : 3]) { 
            translate([leftOffset + (i * gridWidth/4), totalHeight - (borderWidth / 2), -1]) 
            cylinder(h=thickness + 2, r=holeRad); 
        } 
    } 

    // Bottom Border
    if (hasBottom) { 
        for (i = [1 : 3]) { 
            translate([leftOffset + (i * gridWidth/4), borderWidth / 2, -1]) 
            cylinder(h=thickness + 2, r=holeRad); 
        } 
    } 
    
    // Central wire pass-through hole in the middle of the X
    translate([totalWidth/2, totalHeight/2, -1]) 
    cylinder(d=25, h=thickness + 2);
}