/// <summary>
/// Create a sphere.
/// </summary>
/// <param name="radius">
/// A <see cref="Single"/> that specifies the radius of the sphere.
/// </param>
/// <param name="slices">
/// A <see cref="Int32"/> that specifies the number of horizontal subdivisions of the sphere.
/// </param>
/// <param name="stacks">
/// A <see cref="Int32"/> that specifies the number of vertical subdivisions of the sphere.
/// </param>
/// <returns>
/// It returns a <see cref="VertexArrayObject"/> defining the following semantics:
/// - Positions
/// - Normals
/// </returns>
public static VertexArrayObject CreateSphere(float radius, int slices, int stacks)
{
VertexArrayObject vertexArray = new VertexArrayObject();
// Vertex generation
Vertex3f[] position, normal;
ushort[] indices;
int vertexCount;
GenerateSphere(radius, slices, stacks, out position, out normal, out indices, out vertexCount);
// Buffer definition
ArrayBufferObject <Vertex3f> positionBuffer = new ArrayBufferObject <Vertex3f>(BufferObjectHint.StaticCpuDraw);
positionBuffer.Create(position);
vertexArray.SetArray(positionBuffer, VertexArraySemantic.Position);
ArrayBufferObject <Vertex3f> normalBuffer = new ArrayBufferObject <Vertex3f>(BufferObjectHint.StaticCpuDraw);
normalBuffer.Create(normal);
vertexArray.SetArray(normalBuffer, VertexArraySemantic.Normal);
ElementBufferObject <ushort> elementBuffer = new ElementBufferObject <ushort>(BufferObjectHint.StaticCpuDraw);
elementBuffer.Create(indices);
vertexArray.SetElementArray(PrimitiveType.TriangleStrip, elementBuffer);
return(vertexArray);
}
/// <summary>
/// Ensure that all required resources are created.
/// </summary>
/// <param name="ctx">
/// The <see cref="GraphicsContext"/> used for allocating resources.
/// </param>
public override void Create(GraphicsContext ctx)
{
CheckCurrentContext(ctx);
if (ArrayIndices.Exists(ctx) == false)
{
ArrayIndices.Create(ctx);
}
}
/// <summary>
///
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="dx"></param>
/// <param name="dy"></param>
/// <returns></returns>
public static VertexArrayObject CreatePlane(float x, float y, float z, uint dx, uint dy)
{
VertexArrayObject vertexArray = new VertexArrayObject();
// Vertex generation
Vertex3f[] position = new Vertex3f[(dx + 1) * (dy + 1)];
float x2 = x / 2.0f, y2 = y / 2.0f;
float vdx = x / dx, vdy = y / dy;
int vidx = 0;
for (float vy = -y2; vy <= y2; vy += vdy)
{
for (float vx = -x2; vx <= x2; vx += vdx)
{
Debug.Assert(vidx < position.Length);
position[vidx++] = new Vertex3f(vx, vy, z);
}
}
// Elements generation
List <uint> indices = new List <uint>();
uint vstride = dx + 1;
for (uint i = 0; i < dy; i++)
{
uint yoffset = i * vstride;
// Triangle strip start
indices.Add(yoffset + vstride);
for (uint ix = 0; ix < dx; ix++)
{
uint xoffset = yoffset + ix;
indices.Add(xoffset);
indices.Add(xoffset + vstride + 1);
}
indices.Add(yoffset + vstride - 1);
if (Gl.CurrentExtensions.PrimitiveRestart == false)
{
throw new NotImplementedException();
}
else
{
indices.Add(uint.MaxValue);
}
}
// Buffer definition
ArrayBufferObject <Vertex3f> positionBuffer = new ArrayBufferObject <Vertex3f>(BufferObjectHint.StaticCpuDraw);
positionBuffer.Create(position);
vertexArray.SetArray(positionBuffer, VertexArraySemantic.Position);
ElementBufferObject <uint> elementBuffer = new ElementBufferObject <uint>(BufferObjectHint.StaticCpuDraw);
elementBuffer.Create(indices.ToArray());
elementBuffer.RestartIndexEnabled = Gl.CurrentExtensions.PrimitiveRestart;
vertexArray.SetElementArray(PrimitiveType.TriangleStrip, elementBuffer);
return(vertexArray);
}