# 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 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; face++ )
{
// 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.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 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.uv = uvs;
mesh.triangles = triangles;

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

## C# - Cone

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

float height = 1f;
int nbSides = 18;
int nbHeightSeg = 1; // Not implemented yet

int nbVerticesCap = nbSides + 1;
#region Vertices

// bottom + top + sides
Vector3[] vertices = new Vector3[nbVerticesCap + nbVerticesCap + nbSides * nbHeightSeg * 2 + 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 <= vertices.Length - 4 )
{
float rad = (float)v / nbSides * _2pi;
vert+=2;
v++;
}
vertices[vert] = vertices[ nbSides * 2 + 2 ];
vertices[vert + 1] = vertices[nbSides * 2 + 3 ];
#endregion

#region UVs
Vector2[] uvs = new Vector2[vertices.Length];

// Bottom cap
int u = 0;
uvs[u++] = new Vector2(0.5f, 0.5f);
while (u <= nbSides)
{
float rad = (float)u / nbSides * _2pi;
uvs[u] = new Vector2(Mathf.Cos(rad) * .5f + .5f, Mathf.Sin(rad) * .5f + .5f);
u++;
}

// Top cap
uvs[u++] = new Vector2(0.5f, 0.5f);
while (u <= nbSides * 2 + 1)
{
float rad = (float)u / nbSides * _2pi;
uvs[u] = new Vector2(Mathf.Cos(rad) * .5f + .5f, Mathf.Sin(rad) * .5f + .5f);
u++;
}

// Sides
int u_sides = 0;
while (u <= uvs.Length - 4 )
{
float t = (float)u_sides / nbSides;
uvs[u] = new Vector3(t, 1f);
uvs[u + 1] = new Vector3(t, 0f);
u += 2;
u_sides++;
}
uvs[u] = new Vector2(1f, 1f);
uvs[u + 1] = new Vector2(1f, 0f);
#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++;

// Sides
while( tri <= nbTriangles )
{
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;
}
#endregion

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

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