Going 3D

Object Mesh

I want to define a structure that holds the information of the geometry of the 3D object. Something like a blueprint to draw as many objects of that geometry. Normally, this type of structure is called a Mesh. It contains all the information that defines the shape of the 3D object.

Quad Mesh

A Quad is a rectangular object that is flat in one of the 3D axes. Think of it as a plane. The Quad is nothing more that 2 triangles together and can be expressed with 6 vertices.

// 6 vertices with size 3 each
float vertices[6*3] = {
    -0.5f, -0.5f, 0.0f,
    0.5f,  -0.5f, 0.0f,
    0.5f,  0.5f,  0.0f,
    0.5f,  0.5f,  0.0f,
    -0.5f, 0.5f,  0.0f,
    -0.5f, -0.5f, 0.0f,
};

And the mesh object would look something like this:

struct QuadMesh {
    float vertices[18];
    uint32_t numVertices;
    uint32_t vertexSize;
};

// Function that constructs a QuadMesh
QuadMesh CreateQuadMesh() {
    QuadMesh mesh = {
        .vertices{
            -0.5f, -0.5f, 0.0f,
            0.5f,  -0.5f, 0.0f,
            0.5f,  0.5f,  0.0f,
            0.5f,  0.5f,  0.0f,
            -0.5f, 0.5f,  0.0f,
            -0.5f, -0.5f, 0.0f,
        },
        .numVertices = 6,
        .vertexSize = 3,
    };

    return mesh;
}

Here I have also created a constructor function that creates a QuadMesh. I also want to add a function that draws a QuadMesh. This function will call the Renderer_DrawTriangles method that we have been using.

void Renderer_DrawQuad(Renderer *r, Vec3 position, Vec3 rotation, Vec3 scale,
                       ColorRGBA color) {
    if (r == nullptr) {
        return;
    }

    QuadMesh mesh = CreateQuadMesh();

    Renderer_DrawTriangles(r, mesh.vertices, mesh.numVertices, mesh.vertexSize,
                           position, rotation, scale, color);
}

Cube Mesh

I can also do the same for a 3D Cube object. A cube is composed of 6 faces (Quads).

CubeMesh CreateCubeMesh() {
    CubeMesh mesh = {
        .vertices{
            -0.5f, -0.5f, -0.5f,
            0.5f,  -0.5f, -0.5f,
            0.5f,  0.5f,  -0.5f,
            0.5f,  0.5f,  -0.5f,
            -0.5f, 0.5f,  -0.5f,
            -0.5f, -0.5f, -0.5f,

            -0.5f, -0.5f, 0.5f, 
            0.5f,  -0.5f, 0.5f, 
            0.5f,  0.5f,  0.5f, 
            0.5f,  0.5f,  0.5f, 
            -0.5f, 0.5f,  0.5f, 
            -0.5f, -0.5f, 0.5f, 

            -0.5f, 0.5f,  0.5f, 
            -0.5f, 0.5f,  -0.5f,
            -0.5f, -0.5f, -0.5f,
            -0.5f, -0.5f, -0.5f,
            -0.5f, -0.5f, 0.5f, 
            -0.5f, 0.5f,  0.5f, 

            0.5f,  0.5f,  0.5f, 
            0.5f,  0.5f,  -0.5f,
            0.5f,  -0.5f, -0.5f,
            0.5f,  -0.5f, -0.5f,
            0.5f,  -0.5f, 0.5f, 
            0.5f,  0.5f,  0.5f, 

            -0.5f, -0.5f, -0.5f,
            0.5f,  -0.5f, -0.5f,
            0.5f,  -0.5f, 0.5f, 
            0.5f,  -0.5f, 0.5f, 
            -0.5f, -0.5f, 0.5f, 
            -0.5f, -0.5f, -0.5f,

            -0.5f, 0.5f,  -0.5f,
            0.5f,  0.5f,  -0.5f,
            0.5f,  0.5f,  0.5f, 
            0.5f,  0.5f,  0.5f, 
            -0.5f, 0.5f,  0.5f, 
            -0.5f, 0.5f,  -0.5f,
        },
        .numVertices = 36,
        .vertexSize = 3,
    };

    return mesh;
}

And the function that draws a cube:

void Renderer_DrawCube(Renderer *r, Vec3 position, Vec3 rotation, Vec3 scale,
                       ColorRGBA color) {
    if (r == nullptr) {
        return;
    }

    CubeMesh mesh = CreateCubeMesh();

    Renderer_DrawTriangles(r, mesh.vertices, mesh.numVertices, mesh.vertexSize,
                           position, rotation, scale, color);
}
Camera Edge Functions
Squared Wave SVG