# ProceduralPrimitives

(Difference between revisions)

Author: Bérenger.

## Description

Use those scripts to procedurally create primitive meshes, with custom parameters. More to come later. If anyone has the code for a teapot, that'd be great. I guess it's a tiny bit more complicated though.

## Usage

The entry point of those script must be a reference to a meshfilter's mesh. The return value is that mesh filled up.

## C# - Plane

```// You can change that line to provide another MeshFilter
MeshFilter filter = gameObject.AddComponent< MeshFilter >();
Mesh mesh = filter.mesh;
mesh.Clear();

float length = 1f;
float width = 1f;
int resX = 2; // 2 minimum
int resZ = 2;

#region Vertices
Vector3[] vertices = new Vector3[ resX * resZ ];
for(int z = 0; z < resZ; z++)
{
// [ -length / 2, length / 2 ]
float zPos = ((float)z / (resZ - 1) - .5f) * length;
for(int x = 0; x < resX; x++)
{
// [ -width / 2, width / 2 ]
float xPos = ((float)x / (resX - 1) - .5f) * width;
vertices[ x + z * resX ] = new Vector3( xPos, 0f, zPos );
}
}
#endregion

#region Normals
Vector3[] normals = new Vector3[ vertices.Length ];
{
for(int i = 0; i < normals.Length; i++)
normals[i] = Vector3.up;
};
#endregion

#region UVs
Vector2[] uvs = new Vector2[ vertices.Length ];
for(int v = 0; v < resZ; v++)
{
for(int u = 0; u < resX; u++)
{
uvs[ u + v * resX ] = new Vector2( (float)u / (resX - 1), (float)v / (resZ - 1) );
}
}
#endregion

#region Triangles
int nbFaces = (resX - 1) * (resZ - 1);
int[] triangles = new int[ nbFaces * 6 ];
int t = 0;
for(int face = 0; face < nbFaces; n++ )
{
// Retrieve lower left corner from face ind
int i = face % (resX - 1) + (face / (resZ - 1) * resX);

triangles[t++] = i + resX;
triangles[t++] = i + 1;
triangles[t++] = i;

triangles[t++] = i + resX;
triangles[t++] = i + resX + 1;
triangles[t++] = i + 1;
}
#endregion

mesh.vertices = vertices;
mesh.normals = normals;
mesh.uv = uvs;
mesh.triangles = triangles;

mesh.RecalculateNormals();
mesh.RecalculateBounds();
mesh.Optimize();```

## C# - Box

```// You can change that line to provide another MeshFilter
MeshFilter filter = gameObject.AddComponent< MeshFilter >();
Mesh mesh = filter.mesh;
mesh.Clear();

float length = 1f;
float width = 1f;
float height = 1f;

#region Vertices
Vector3 p0 = new Vector3( -length * .5f,	-width * .5f, height * .5f );
Vector3 p1 = new Vector3( length * .5f, 	-width * .5f, height * .5f );
Vector3 p2 = new Vector3( length * .5f, 	-width * .5f, -height * .5f );
Vector3 p3 = new Vector3( -length * .5f,	-width * .5f, -height * .5f );

Vector3 p4 = new Vector3( -length * .5f,	width * .5f,  height * .5f );
Vector3 p5 = new Vector3( length * .5f, 	width * .5f,  height * .5f );
Vector3 p6 = new Vector3( length * .5f, 	width * .5f,  -height * .5f );
Vector3 p7 = new Vector3( -length * .5f,	width * .5f,  -height * .5f );

Vector3[] vertices = new Vector3[]
{
// Bottom
p0, p1, p2, p3,

// Left
p7, p4, p0, p3,

// Front
p4, p5, p1, p0,

// Back
p6, p7, p3, p2,

// Right
p5, p6, p2, p1,

// Top
p7, p6, p5, p4
};
#endregion

#region Normals
Vector3 up 	= Vector3.up;
Vector3 down 	= Vector3.down;
Vector3 front 	= Vector3.forward;
Vector3 back 	= Vector3.back;
Vector3 left 	= Vector3.left;
Vector3 right 	= Vector3.right;

Vector3[] normals = new Vector3[]
{
// Bottom
down, down, down, down,

// Left
left, left, left, left,

// Front
front, front, front, front,

// Back
back, back, back, back,

// Right
right, right, right, right,

// Top
up, up, up, up
};
#endregion

#region UVs
Vector2 _00 = new Vector2( 0f, 0f );
Vector2 _10 = new Vector2( 1f, 0f );
Vector2 _01 = new Vector2( 0f, 1f );
Vector2 _11 = new Vector2( 1f, 1f );

Vector2[] uvs = new Vector2[]
{
// Bottom
_11, _01, _00, _10,

// Left
_11, _01, _00, _10,

// Front
_11, _01, _00, _10,

// Back
_11, _01, _00, _10,

// Right
_11, _01, _00, _10,

// Top
_11, _01, _00, _10,
};
#endregion

#region Triangles
int[] triangles = new int[]
{
// Bottom
3, 1, 0,
3, 2, 1,

// Left
3 + 4 * 1, 1 + 4 * 1, 0 + 4 * 1,
3 + 4 * 1, 2 + 4 * 1, 1 + 4 * 1,

// Front
3 + 4 * 2, 1 + 4 * 2, 0 + 4 * 2,
3 + 4 * 2, 2 + 4 * 2, 1 + 4 * 2,

// Back
3 + 4 * 3, 1 + 4 * 3, 0 + 4 * 3,
3 + 4 * 3, 2 + 4 * 3, 1 + 4 * 3,

// Right
3 + 4 * 4, 1 + 4 * 4, 0 + 4 * 4,
3 + 4 * 4, 2 + 4 * 4, 1 + 4 * 4,

// Top
3 + 4 * 5, 1 + 4 * 5, 0 + 4 * 5,
3 + 4 * 5, 2 + 4 * 5, 1 + 4 * 5,

};
#endregion

mesh.vertices = vertices;
mesh.normals = normals;
mesh.uv = uvs;
mesh.triangles = triangles;

mesh.RecalculateNormals();
mesh.RecalculateBounds();
mesh.Optimize();```

## C# - Cone (in progress)

```MeshFilter filter = gameObject.AddComponent<MeshFilter>();
Mesh mesh = filter.mesh;
mesh.Clear();

float height = 1f;
int nbSides = 18;
int nbHeightSeg = 1;

int nbVerticesCap = nbSides + 1;
#region Vertices

// bottom + top + sides
Vector3[] vertices = new Vector3[nbVerticesCap + nbVerticesCap + nbSides * nbHeightSeg * 2];
int vert = 0;
float _2pi = Mathf.PI * 2f;

// Bottom cap
vertices[vert++] = new Vector3(0f, 0f, 0f);
while( vert <= nbSides )
{
float rad = (float)vert / nbSides * _2pi;
vert++;
}

// Top cap
vertices[vert++] = new Vector3(0f, height, 0f);
while (vert <= nbSides * 2 + 1)
{
float rad = (float)(vert - nbSides - 1)  / nbSides * _2pi;
vert++;
}

// Sides
int v = 0;
while (vert <= nbSides * 2 + nbSides * 2 + 1)
{
float rad = (float)v / nbSides * _2pi;
vert+=2;
v++;
}
#endregion

/*#region Normals
Vector3 up = Vector3.up;
Vector3 down = Vector3.down;
Vector3 front = Vector3.forward;
Vector3 back = Vector3.back;
Vector3 left = Vector3.left;
Vector3 right = Vector3.right;

Vector3[] normals = new Vector3[]
{
};
#endregion

#region UVs
Vector2 _00 = new Vector2(0f, 0f);
Vector2 _10 = new Vector2(1f, 0f);
Vector2 _01 = new Vector2(0f, 1f);
Vector2 _11 = new Vector2(1f, 1f);

Vector2[] uvs = new Vector2[]
{
};
#endregion*/

#region Triangles
int nbTriangles = nbSides + nbSides + nbSides*2;
int[] triangles = new int[nbTriangles * 3 + 3];

// Bottom cap
int tri = 0;
int i = 0;
while (tri < nbSides - 1)
{
triangles[ i ] = 0;
triangles[ i+1 ] = tri + 1;
triangles[ i+2 ] = tri + 2;
tri++;
i += 3;
}
triangles[i] = 0;
triangles[i + 1] = tri + 1;
triangles[i + 2] = 1;
tri++;
i += 3;

// Top cap
//tri++;
while (tri < nbSides*2)
{
triangles[ i ] = tri + 2;
triangles[i + 1] = tri + 1;
triangles[i + 2] = nbVerticesCap;
tri++;
i += 3;
}

triangles[i] = nbVerticesCap + 1;
triangles[i + 1] = tri + 1;
triangles[i + 2] = nbVerticesCap;
tri++;
i += 3;
tri++;
//i += 3;

// Sides
while (tri < nbTriangles - 1)
{
triangles[ i ] = tri + 2;
triangles[ i+1 ] = tri + 1;
triangles[ i+2 ] = tri + 0;
tri++;
i += 3;

triangles[ i ] = tri + 1;
triangles[ i+1 ] = tri + 2;
triangles[ i+2 ] = tri + 0;
tri++;
i += 3;
}

triangles[i] = nbVerticesCap * 2;
triangles[i + 1] = tri+1;
triangles[i + 2] = tri + 0;
tri++;
i += 3;

triangles[i] = tri;
triangles[i + 1] = nbVerticesCap * 2;
triangles[i + 2] = nbVerticesCap * 2 + 1;
tri++;
#endregion

mesh.vertices = vertices;
//mesh.normals = normals;
//mesh.uv = uvs;
mesh.triangles = triangles;

mesh.RecalculateNormals();
mesh.RecalculateBounds();
mesh.Optimize();```