/// <summary>
/// 顶点属性Buffer。描述顶点的位置或颜色或UV等各种属性。
/// <para>每个<see cref="VertexAttributeBuffer<T>"/>仅描述其中一个属性。</para>
/// <para>Vertex Buffer Object that describes vertex' property(position, color, uv coordinate, etc.).</para>
/// <para>Each <see cref="VertexAttributeBuffer<T>"/> describes only 1 property.</para>
/// <para>Note: If <typeparamref name="T"/> matches one of this.Config's value, then (Ptr.ByteLength / (Ptr.DataSize * Ptr.DataTypeByteLength)) equals (Ptr.Length).</para>
/// <para><typeparamref name="T"/> is type of element of this array in application level.</para>
/// </summary>
/// <param name="varNameInVertexShader">此顶点属性VBO对应于vertex shader中的哪个in变量？<para>Mapping variable's name in vertex shader.</para></param>
/// <param name="config">This <paramref name="config"/> decides parameters' values in glVertexAttribPointer(attributeLocation, size, type, false, 0, IntPtr.Zero);
/// </param>
/// <param name="usage"></param>
/// <param name="instancedDivisor">0: not instanced. 1: instanced divisor is 1.</param>
/// <param name="patchVertexes">How many vertexes makes a patch? No patch if <paramref name="patchVertexes"/> is 0.</param>
public VertexAttributeBuffer(string varNameInVertexShader, VertexAttributeConfig config, BufferUsage usage, uint instancedDivisor = 0, int patchVertexes = 0)
: base(usage)
{
this.VarNameInVertexShader = varNameInVertexShader;
this.Config = config;
this.InstancedDivisor = instancedDivisor;
this.PatchVertexes = patchVertexes;
}
/// <summary>
/// Vertex' attribute buffer's pointer.
/// </summary>
/// <param name="varNameInVertexShader">此顶点属性VBO对应于vertex shader中的哪个in变量？<para>Mapping variable's name in vertex shader.</para></param>
/// <param name="bufferId">用glGenBuffers()得到的VBO的Id。<para>Id got from glGenBuffers();</para></param>
/// <param name="config">This <paramref name="config"/> decides parameters' values in glVertexAttribPointer(attributeLocation, size, type, false, 0, IntPtr.Zero);
/// </param>
/// <param name="length">此VBO含有多个个元素？<para>How many elements?</para></param>
/// <param name="byteLength">此VBO中的数据在内存中占用多少个字节？<para>How many bytes in this buffer?</para></param>
/// <param name="instancedDivisor">0: not instanced. 1: instanced divisor is 1.</param>
/// <param name="patchVertexes">How many vertexes makes a patch? No patch if <paramref name="patchVertexes"/> is 0.</param>
internal VertexAttributeBufferPtr(string varNameInVertexShader,
uint bufferId, VertexAttributeConfig config, int length, int byteLength,
uint instancedDivisor = 0, int patchVertexes = 0)
: base(bufferId, length, byteLength)
{
if (glVertexAttribPointer == null)
{
glVertexAttribPointer = OpenGL.GetDelegateFor <OpenGL.glVertexAttribPointer>();
glEnableVertexAttribArray = OpenGL.GetDelegateFor <OpenGL.glEnableVertexAttribArray>();
glVertexAttribDivisor = OpenGL.GetDelegateFor <OpenGL.glVertexAttribDivisor>();
glPatchParameteri = OpenGL.GetDelegateFor <OpenGL.glPatchParameteri>();
glPatchParameterfv = OpenGL.GetDelegateFor <OpenGL.glPatchParameterfv>();
}
this.VarNameInVertexShader = varNameInVertexShader;
this.Config = config;
this.InstancedDivisor = instancedDivisor;
this.PatchVertexes = patchVertexes;
}
/// <summary>
/// Gets parameter values for glVertexAttribPointer() and glEnable/DisableVertexAttribArray().
/// </summary>
/// <param name="config"></param>
/// <param name="locationCount"></param>
/// <param name="dataSize"></param>
/// <param name="dataType"></param>
/// <param name="stride"></param>
/// <param name="startOffsetUnit"></param>
public static void Parse(this VertexAttributeConfig config, out int locationCount, out int dataSize, out uint dataType, out int stride, out int startOffsetUnit)
{
locationCount = 1;
//dataSize = 0;
//dataType = 0;
stride = 0;
startOffsetUnit = 0;
switch (config)
{
case VertexAttributeConfig.Byte:
dataSize = 1;
dataType = OpenGL.GL_BYTE;
break;
case VertexAttributeConfig.BVec2:
dataSize = 2;
dataType = OpenGL.GL_BYTE;
break;
case VertexAttributeConfig.BVec3:
dataSize = 3;
dataType = OpenGL.GL_BYTE;
break;
case VertexAttributeConfig.BVec4:
dataSize = 4;
dataType = OpenGL.GL_BYTE;
break;
case VertexAttributeConfig.Int:
dataSize = 1;
dataType = OpenGL.GL_INT;
break;
case VertexAttributeConfig.IVec2:
dataSize = 2;
dataType = OpenGL.GL_INT;
break;
case VertexAttributeConfig.IVec3:
dataSize = 3;
dataType = OpenGL.GL_INT;
break;
case VertexAttributeConfig.IVec4:
dataSize = 4;
dataType = OpenGL.GL_INT;
break;
case VertexAttributeConfig.UInt:
dataSize = 1;
dataType = OpenGL.GL_UNSIGNED_INT;
break;
case VertexAttributeConfig.UVec2:
dataSize = 2;
dataType = OpenGL.GL_UNSIGNED_INT;
break;
case VertexAttributeConfig.UVec3:
dataSize = 3;
dataType = OpenGL.GL_UNSIGNED_INT;
break;
case VertexAttributeConfig.UVec4:
dataSize = 4;
dataType = OpenGL.GL_UNSIGNED_INT;
break;
case VertexAttributeConfig.Float:
dataSize = 1;
dataType = OpenGL.GL_FLOAT;
break;
case VertexAttributeConfig.Vec2:
dataSize = 2;
dataType = OpenGL.GL_FLOAT;
break;
case VertexAttributeConfig.Vec3:
dataSize = 3;
dataType = OpenGL.GL_FLOAT;
break;
case VertexAttributeConfig.Vec4:
dataSize = 4;
dataType = OpenGL.GL_FLOAT;
break;
case VertexAttributeConfig.Double:
dataSize = 1;
dataType = OpenGL.GL_DOUBLE;
break;
case VertexAttributeConfig.DVec2:
dataSize = 2;
dataType = OpenGL.GL_DOUBLE;
break;
case VertexAttributeConfig.DVec3:
dataSize = 3;
dataType = OpenGL.GL_DOUBLE;
break;
case VertexAttributeConfig.DVec4:
dataSize = 4;
dataType = OpenGL.GL_DOUBLE;
break;
case VertexAttributeConfig.Mat2:
locationCount = 2;
dataSize = 2;
dataType = OpenGL.GL_FLOAT;
stride = Marshal.SizeOf(typeof(mat2));
startOffsetUnit = Marshal.SizeOf(typeof(vec2));
break;
case VertexAttributeConfig.Mat3:
locationCount = 3;
dataSize = 3;
dataType = OpenGL.GL_FLOAT;
stride = Marshal.SizeOf(typeof(mat3));
startOffsetUnit = Marshal.SizeOf(typeof(vec3));
break;
case VertexAttributeConfig.Mat4:
locationCount = 4;
dataSize = 4;
dataType = OpenGL.GL_FLOAT;
stride = Marshal.SizeOf(typeof(mat4));
startOffsetUnit = Marshal.SizeOf(typeof(vec4));
break;
default:
throw new System.NotImplementedException();
}
}
