Step 1: Building the Outer Walls of the House
We will start creating code from the pseudo code created earlier. The image below can be used as reference when looking at the code to generate each of the mesh objects.
In this example, the X corrdinate value will be our house length (L), the Y coordinate value will be the house width (W), and the Z coordinate value will be the wall height (H) . The image to the right should look familiar, it shows the solid that was created in the previous lesson (Creating a Cube) and is the exact same shape that would be created if the house parameters were set to the following values:
House_Length (L) = 15
House_Width (W) = 10
Wall_Height (H) = 10
We can use information to create the block that will represent the outer walls of the house.
- This section of code will define each of the faces of the outer mesh. Each face of the mesh is defined by an array of 4 points. Note: Remember the Right Hand Rule: The order in which the points are defined is critical to creating a water tight solid. The surface normal of each face should point away from the center of the object being created.
- Copy and paste the following code into the code window just below the variables and parameters that were entered in the previous step: var outer_mesh = new Mesh3D(); outer_mesh.quad([0 , 0 , 0 ], [0 , W , 0], [L, W, 0], [L, 0, 0]); //box bottom outer_mesh.quad([0 , 0 , 0 ], [L , 0 , 0], [L, 0, H], [0, 0, H]); //box front outer_mesh.quad([L , 0 , 0 ], [L , W , 0], [L, W, H], [L, 0, H]); //box right outer_mesh.quad([0 , 0 , 0 ], [0 , 0 , H], [0, W, H], [0, W, 0]); //box left outer_mesh.quad([0 , W , 0 ], [0 , W , H], [L, W, H], [L, W, 0]); //box back outer_mesh.quad([0 , 0 , H ], [L , 0 , H], [L, W, H], [0, W, H]); //box top
- In the code above you can see that instead of X, Y, and Z values we have mixed in variables that represents the value entered by the user with the sliders you saw in the introduction to this project.
Step 2: Create a Smaller Block to Hollow Out the Block
The size of the inner block essentially defines the thickness of the walls. To create a wall 1mm thick, the inner block will need to be reduced by 2mm in length and 2mm in width. This can done easily with simple math. As seen below we create a new mesh called inner_mesh and simply subtract 2 from every L and W value used when creating the outer_mesh.
Note:The image below shows the result of subtracting the inner_mesh (which we will build in this step) from the outer_mesh (which we created in the previous step). The code for the subtraction will happen later in the coding process.
- Because we want to create the new block slightly smaller than the original block we can start with a copy of the outer_mesh code from the first block. Instead of making the block the exact same size we will subtract 2 from each of the L and W values. The code to create the inner_mesh shape can be copied from the next step and pasted into the code window just below.
- Instruction image var inner_mesh = new Mesh3D(); inner_mesh.quad([0 , 0 , 0], [0 , W - 2, 0], [L - 2, W - 2, 0], [L - 2, 0 , 0]); //box bottom inner_mesh.quad([0 , 0 , 0], [L - 2, 0 , 0], [L - 2, 0 , H], [0 , 0 , H]); //box front inner_mesh.quad([L - 2, 0 , 0], [L - 2, W - 2, 0], [L - 2, W - 2, H], [L - 2, 0 , H]); //box right inner_mesh.quad([0 , 0 , 0], [0 , 0 , H], [0 , W - 2, H], [0 , W - 2, 0]); //box left inner_mesh.quad([0 , W - 2, 0], [0 , W - 2, H], [L - 2, W - 2, H], [L - 2, W - 2, 0] ); //box back inner_mesh.quad([0 , 0 , H], [L - 2, 0 , H], [L - 2, W - 2, H], [0 , W - 2, H]); //box top
Step 3: Create a Roof Shape That Can Be Placed on Top of the House
The roof is created in a similar fashion to both the inner and outer mesh, but with a triangular twist. The roof is made of 3 rectangular or quad faces and the 2 ends of the roof are triangles. Each is reflected in the lines of code shown below.
In order to create an over hang on the roof we need to make it slightly larger than the outer mesh. This can be accomplished by adding 2mm to the length and width.
The unique item in this code is the calculation that locates the points that define the peak of each triangle. To perfectly center the peak point we must use the following formula (W + 2)/2 this adds 2mm to the overall width of the roof to create the overhangs, then divides that value in half to locate the exact center of the roof.
- To create the roof we will need to define each of the faces shown in the image below.
- In the image below you will see that each line of code is defining one of the faces of the roof. There are 3 quads and 2 triangles. The next instruction includes the code that can be copied and pasted into the code interfaces.
- var roof_mesh = new Mesh3D(); roof_mesh.quad([0, 0 , 0], [0 , W + 2 , 0 ], [L + 2, W + 2 , 0 ], [L + 2, 0 , 0 ]); //roof bottom roof_mesh.quad([0, 0 , 0], [L + 2, 0 , 0 ], [L + 2, (W + 2)/2, RH], [0 , (W + 2)/2, RH]); //roof top right roof_mesh.quad([0, W + 2, 0], [0 , (W + 2)/2, RH], [L + 2, (W + 2)/2, RH], [L + 2, W + 2 , 0 ]); //roof top left roof_mesh.triangle([0 , 0, 0], [0 , (W + 2)/2, RH], [0 , W + 2 , 0 ]); //roof left tri roof_mesh.triangle([L + 2, 0, 0], [L + 2, W + 2 , 0 ], [L + 2, (W + 2)/2, RH]); //roof right tri
- Continue to the next step.
Step 4: Step Back and Review
Congratulations! You now have all the shapes you need to create the house. Since you are in the middle of coding, you can't see these shapes yet, but take a minute and review the image below.
On the left you can see what the shapes would look like if we stopped here. To make it easier to generate the shapes we started then all at the 0, 0, 0 position, so every shape currently shares a corner point with all the other shapes.
If you were building manually, without code, you would group the large and small block first to hollow out the walls, then you would group the walls with the roof. The orange shape on the right is what that final grouping would look like.....wait.....that doesn't look right.
That is because we need to position the shapes before we begin to combine them.
We will do that in the next lesson.
Note: The image below will not be seen when you are creating this section of code.They were created after the shape generator program was written as a way to show the results of adding these transforms to the code.
- Continue to the next lesson.
In the next lesson you will learn to complete the house.
Next Lesson:Completing the House