/// <summary>
/// Creates a <see cref="VertexBuffer"/> filled with <see cref="VertexPositionNormal"/> vertices forming a cylinder.
/// </summary>
/// <remarks>
/// Draw with an INDEXED TriangleList. The values to use are as follows:
/// Vertex Count = slices * (stacks + 1) + 2
/// Primitive Count = slices * (stacks + 1) * 2
/// </remarks>
/// <param name="device">The <see cref="GraphicsDevice"/> that is associated with the created cylinder.</param>
/// <param name="bottomRadius">Radius at the negative Y end. Value should be greater than or equal to 0.0f.</param>
/// <param name="topRadius">Radius at the positive Y end. Value should be greater than or equal to 0.0f.</param>
/// <param name="length">Length of the cylinder along the Y-axis.</param>
/// <param name="slices">Number of slices about the Y axis.</param>
/// <param name="stacks">Number of stacks along the Y axis.</param>
public static Shape3D CreateCylinder(GraphicsDevice device, float bottomRadius, float topRadius, float length, int slices, int stacks)
{
// if both the top and bottom have a radius of zero, just return null, because invalid
if (bottomRadius <= 0 && topRadius <= 0)
{
return(null);
}
Shape3D shape = new Shape3D();
float sliceStep = MathHelper.TwoPi / slices;
float heightStep = length / stacks;
float radiusStep = (topRadius - bottomRadius) / stacks;
float currentHeight = -length / 2;
int vertexCount = (stacks + 1) * slices + 2; //cone = stacks * slices + 1
int triangleCount = (stacks + 1) * slices * 2; //cone = stacks * slices * 2 + slices
int indexCount = triangleCount * 3;
float currentRadius = bottomRadius;
VertexPositionNormal[] vertices = new VertexPositionNormal[vertexCount];
// Start at the bottom of the cylinder
int currentVertex = 0;
vertices[currentVertex++] = new VertexPositionNormal(new Vector3(0, currentHeight, 0), Vector3.Down);
for (int i = 0; i <= stacks; i++)
{
float sliceAngle = 0;
for (int j = 0; j < slices; j++)
{
float x = currentRadius * (float)Math.Cos(sliceAngle);
float y = currentHeight;
float z = currentRadius * (float)Math.Sin(sliceAngle);
Vector3 position = new Vector3(x, y, z);
vertices[currentVertex++] = new VertexPositionNormal(position, Vector3.Normalize(position));
sliceAngle += sliceStep;
}
currentHeight += heightStep;
currentRadius += radiusStep;
}
vertices[currentVertex++] = new VertexPositionNormal(new Vector3(0, length / 2, 0), Vector3.Up);
// Create the actual vertex buffer object
shape.VertexBuffer = new VertexBuffer(device, VertexPositionNormal.SizeInBytes * vertices.Length, BufferUsage.None);
shape.VertexBuffer.SetData <VertexPositionNormal>(vertices);
shape.IndexBuffer = CreateIndexBuffer(device, vertexCount, indexCount, slices);
shape.VertexCount = vertexCount;
shape.TriangleCount = triangleCount;
shape.VertexDeclaration = new VertexDeclaration(device, VertexPositionNormal.VertexElements);
shape.VertexSizeInBytes = VertexPositionNormal.SizeInBytes;
return(shape);
}
/// <summary>
/// Creates a <see cref="VertexBuffer"/> filled with <see cref="VertexPositionNormal"/> vertices forming a sphere.
/// </summary>
/// <remarks>
/// Draw with an INDEXED TriangleList. The values to use are as follows:
/// Vertex Count = slices * (stacks - 1) + 2
/// Primitive Count = slices * (stacks - 1) * 2
/// </remarks>
/// <param name="device">The <see cref="GraphicsDevice"/> that is associated with the created sphere.</param>
/// <param name="radius">Radius of the sphere. This value should be greater than or equal to 0.0f.</param>
/// <param name="slices">Number of slices about the Y axis.</param>
/// <param name="stacks">Number of stacks along the Y axis. Should be 2 or greater. (stack of 1 is just a cylinder)</param>
public static Shape3D CreateSphere(GraphicsDevice device, float radius, int slices, int stacks)
{
Shape3D shape = new Shape3D();
float sliceStep = MathHelper.TwoPi / slices;
float stackStep = MathHelper.Pi / stacks;
int vertexCount = slices * (stacks - 1) + 2;
int triangleCount = slices * (stacks - 1) * 2;
int indexCount = triangleCount * 3;
VertexPositionNormal[] sphereVertices = new VertexPositionNormal[vertexCount];
int currentVertex = 0;
sphereVertices[currentVertex++] = new VertexPositionNormal(new Vector3(0, -radius, 0), Vector3.Down);
float stackAngle = MathHelper.Pi - stackStep;
for (int i = 0; i < stacks - 1; i++)
{
float sliceAngle = 0;
for (int j = 0; j < slices; j++)
{
//NOTE: y and z were switched from normal spherical coordinates because the sphere is "oriented" along the Y axis as opposed to the Z axis
float x = (float)(radius * Math.Sin(stackAngle) * Math.Cos(sliceAngle));
float y = (float)(radius * Math.Cos(stackAngle));
float z = (float)(radius * Math.Sin(stackAngle) * Math.Sin(sliceAngle));
Vector3 position = new Vector3(x, y, z);
sphereVertices[currentVertex++] = new VertexPositionNormal(position, Vector3.Normalize(position));
sliceAngle += sliceStep;
}
stackAngle -= stackStep;
}
sphereVertices[currentVertex++] = new VertexPositionNormal(new Vector3(0, radius, 0), Vector3.Up);
// Create the actual vertex buffer
shape.VertexBuffer = new VertexBuffer(device, VertexPositionNormal.SizeInBytes * sphereVertices.Length, BufferUsage.None);
shape.VertexBuffer.SetData <VertexPositionNormal>(sphereVertices);
shape.IndexBuffer = CreateIndexBuffer(device, vertexCount, indexCount, slices);
shape.VertexCount = vertexCount;
shape.TriangleCount = triangleCount;
shape.VertexDeclaration = new VertexDeclaration(device, VertexPositionNormal.VertexElements);
shape.VertexSizeInBytes = VertexPositionNormal.SizeInBytes;
return(shape);
}
/// <summary>
/// Creates a <see cref="VertexBuffer"/> filled with <see cref="VertexPositionNormal"/> vertices forming a box.
/// </summary>
/// <remarks>Always draw using a non-indexed TriangleList of 12 primitives.</remarks>
/// <param name="device">The <see cref="GraphicsDevice"/> that is associated with the created box.</param>
/// <param name="width">Width of the box, along the x-axis.</param>
/// <param name="height">Height of the box, along the y-axis.</param>
/// <param name="depth">Depth of the box, along the z-axis.</param>
public static Shape3D CreateBox(GraphicsDevice device, float width, float height, float depth)
{
Shape3D shape = new Shape3D();
// Because the box is centered at the origin, need to divide by two to find the + and - offsets
width = width / 2.0f;
height = height / 2.0f;
depth = depth / 2.0f;
VertexPositionNormal[] cubeVertices = new VertexPositionNormal[36];
Vector3 topLeftFront = new Vector3(-width, height, depth);
Vector3 bottomLeftFront = new Vector3(-width, -height, depth);
Vector3 topRightFront = new Vector3(width, height, depth);
Vector3 bottomRightFront = new Vector3(width, -height, depth);
Vector3 topLeftBack = new Vector3(-width, height, -depth);
Vector3 topRightBack = new Vector3(width, height, -depth);
Vector3 bottomLeftBack = new Vector3(-width, -height, -depth);
Vector3 bottomRightBack = new Vector3(width, -height, -depth);
Vector3 frontNormal = new Vector3(0.0f, 0.0f, 1.0f);
Vector3 backNormal = new Vector3(0.0f, 0.0f, -1.0f);
Vector3 topNormal = new Vector3(0.0f, 1.0f, 0.0f);
Vector3 bottomNormal = new Vector3(0.0f, -1.0f, 0.0f);
Vector3 leftNormal = new Vector3(-1.0f, 0.0f, 0.0f);
Vector3 rightNormal = new Vector3(1.0f, 0.0f, 0.0f);
// Front face.
cubeVertices[1] = new VertexPositionNormal(topLeftFront, frontNormal);
cubeVertices[0] = new VertexPositionNormal(bottomLeftFront, frontNormal);
cubeVertices[2] = new VertexPositionNormal(topRightFront, frontNormal);
cubeVertices[4] = new VertexPositionNormal(bottomLeftFront, frontNormal);
cubeVertices[3] = new VertexPositionNormal(bottomRightFront, frontNormal);
cubeVertices[5] = new VertexPositionNormal(topRightFront, frontNormal);
// Back face.
cubeVertices[7] = new VertexPositionNormal(topLeftBack, backNormal);
cubeVertices[6] = new VertexPositionNormal(topRightBack, backNormal);
cubeVertices[8] = new VertexPositionNormal(bottomLeftBack, backNormal);
cubeVertices[10] = new VertexPositionNormal(bottomLeftBack, backNormal);
cubeVertices[9] = new VertexPositionNormal(topRightBack, backNormal);
cubeVertices[11] = new VertexPositionNormal(bottomRightBack, backNormal);
// Top face.
cubeVertices[13] = new VertexPositionNormal(topLeftFront, topNormal);
cubeVertices[12] = new VertexPositionNormal(topRightBack, topNormal);
cubeVertices[14] = new VertexPositionNormal(topLeftBack, topNormal);
cubeVertices[16] = new VertexPositionNormal(topLeftFront, topNormal);
cubeVertices[15] = new VertexPositionNormal(topRightFront, topNormal);
cubeVertices[17] = new VertexPositionNormal(topRightBack, topNormal);
// Bottom face.
cubeVertices[19] = new VertexPositionNormal(bottomLeftFront, bottomNormal);
cubeVertices[18] = new VertexPositionNormal(bottomLeftBack, bottomNormal);
cubeVertices[20] = new VertexPositionNormal(bottomRightBack, bottomNormal);
cubeVertices[22] = new VertexPositionNormal(bottomLeftFront, bottomNormal);
cubeVertices[21] = new VertexPositionNormal(bottomRightBack, bottomNormal);
cubeVertices[23] = new VertexPositionNormal(bottomRightFront, bottomNormal);
// Left face.
cubeVertices[25] = new VertexPositionNormal(topLeftFront, leftNormal);
cubeVertices[24] = new VertexPositionNormal(bottomLeftBack, leftNormal);
cubeVertices[26] = new VertexPositionNormal(bottomLeftFront, leftNormal);
cubeVertices[28] = new VertexPositionNormal(topLeftBack, leftNormal);
cubeVertices[27] = new VertexPositionNormal(bottomLeftBack, leftNormal);
cubeVertices[29] = new VertexPositionNormal(topLeftFront, leftNormal);
// Right face.
cubeVertices[31] = new VertexPositionNormal(topRightFront, rightNormal);
cubeVertices[30] = new VertexPositionNormal(bottomRightFront, rightNormal);
cubeVertices[32] = new VertexPositionNormal(bottomRightBack, rightNormal);
cubeVertices[34] = new VertexPositionNormal(topRightBack, rightNormal);
cubeVertices[33] = new VertexPositionNormal(topRightFront, rightNormal);
cubeVertices[35] = new VertexPositionNormal(bottomRightBack, rightNormal);
// Create the actual vertex buffer
shape.VertexBuffer = new VertexBuffer(device, VertexPositionNormal.SizeInBytes * cubeVertices.Length, BufferUsage.None);
shape.VertexBuffer.SetData <VertexPositionNormal>(cubeVertices);
shape.VertexCount = 36;
shape.TriangleCount = 12;
shape.VertexDeclaration = new VertexDeclaration(device, VertexPositionNormal.VertexElements);
shape.VertexSizeInBytes = VertexPositionNormal.SizeInBytes;
return(shape);
}
