Carna::base::VertexBase Struct Reference

Defines simple-most vertex that only consists of a positional attribute. More...

#include <Vertex.h>

Inheritance diagram for Carna::base::VertexBase:

Public Member Functions
	VertexBase ()
	Initializes position to \(\left(0, 0, 0, 1\right)\).

Public Attributes
float	x
	Holds the positional x-component of this vertex.
float	y
	Holds the positional y-component of this vertex.
float	z
	Holds the positional z-component of this vertex.
float	w
	Holds the positional w-component of this vertex. This will be 1 usually.

Static Public Attributes
static const VertexAttributes	attributes
	Holds the declaration of the vertex format.

Detailed Description

Defines simple-most vertex that only consists of a positional attribute.

Custom Vertex Formats

It is easy to define custom vertex formats. The procedure is best explained with an example. Lets assume you want to define a vertex that has additional properties for normal vectors and 2D texture coordinates.

The first step is to define the missing vertex components. The VertexNormal type already provides a vertex component for normal vectors, so lets define a component for 2D texture coordinates:

struct VertexTexCoord2
{
    float u, v;
};

It is necessary that a vertex component is implemented as a POD, i.e. plain old data type. Virtual methods would mess up the memory layout. However, you might define a constructor that initializes default values, if you wanted.

The next step is to compose the vertex format:

using namespace Carna::base;
struct LightedTexturedVertex
    : public VertexBase
    , public VertexNormal
    , public VertexTexCoord2
{
    static const VertexAttributes attributes;
};

The order of the base classes is arbitrary, but it must be consistent with what comes next, namely the specification of the vertex format.

#include <vector>
using namespace Carna::base;
const VertexAttributes LightedTexturedVertex::attributes = []()->VertexAttributes
{
    using Carna::base::VertexAttribute;  // msvc++ requires us to repeat this
    std::vector< VertexAttribute > attributes;
    attributes.push_back( VertexAttribute( 0, 4, VertexAttribute::TYPE_FLOAT ) );
    attributes.push_back( VertexAttribute( 4, 4, VertexAttribute::TYPE_FLOAT ) );
    attributes.push_back( VertexAttribute( 8, 2, VertexAttribute::TYPE_FLOAT ) );
    return attributes;
}();

You should read the above like:

• Attribute 1 starts at offset 0 and has 4 components, namely the positional x, y, z, w.
• Attribute 2 starts at offset 4 and has 4 components, namely the nx, ny, nz, nw of the normal vector.
• Attribute 3 starts at offset 8 and has 2 components, namely the u, v of the texture coordinates vector.

When writing your shader, you must declare the vertex format consistently:

layout( location = 0 ) in vec4 inPosition;
layout( location = 1 ) in vec4 inNormal;
layout( location = 2 ) in vec2 inTexCoord;

Author

Leonid Kostrykin

Date

1.9.14 - 10.3.15

Definition at line 108 of file Vertex.h.

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The documentation for this struct was generated from the following file:

• include/Carna/base/Vertex.h