Loading Vertex Data

Generating some sample vertex data

struct Vector3;
struct Vector4;
 
struct Vertex
{
    Vector3 position;
    Vector4 color;
}
 
{
    // Create a triangle using three vertexes.
    Vertex vertexData[] = {
        // Position       , Color
        { Vector3(0, 0, 0), Vector4(1, 0, 0, 1) }, // Red
        { Vector3(1, 0, 0), Vector4(0, 1, 0, 1) }, // Green
        { Vector3(1, 1, 0), Vector4(0, 0, 1, 1) }, // Blue
    };
    
    ...
}

Describing our vertex data

When loading vertex data to the graphics device it is necessary to describe the properties of the data so it may be interpreted correctly by the input assembler.

#include <Rendering/VertexFormat.h>
 
{
    // Each vertex consists of two elements, a position and a color.
    // First we describe the position element.
    VertexElement positionElement = {
        0,                                 // There is zero bytes offset in the structure before a position element
        DataFormat::Float,                 // We use floating point data for our coordinates
        3,                                 // We use three components, x, y, z, for the position.
        ElementSemantic::Position,         // The intended use of this element is as a position.
        0                                  // It is the first element using the position semantic.
    };
    
    // Then we describe the color element.
    VertexElement colorElement = {
        3 * sizeof(float),                 // There are three floats, the position element, preceding the color element in our vertex structure.
        DataFormat::Float,                 // We use floating point data for our colors.
        4,                                 // We have four components, rgba, for our color.
        ElementSemantic::Color,            // The intended use of this element is coloring.
        0                                  // It is the first element using the color semantic.
    };
 
    // Create a new vertex format to hold our element descriptions.
    VertexFormat vertexFormat;
    vertexFormat.elements.push_back(positionElement);
    vertexFormat.elements.push_back(colorElement);
    
    ...
}

Loading the vertex data.

#include <Rendering/IBuffers.h>
 
{
    ...
    
    // Get a pointer to the buffer management interface. The device must be initialized previously.
    auto buffers = device->getBuffers();
    
    // Load our vertex data into a new vertex buffer.
    auto vertexBufferHandle = buffers->loadVertexBuffer(
        vertexData,  // Pointer to our vertex data in memory
        3,           // The number of vertexes in our data set.
        vertexFormat // Description of a vertex in the buffer.
    );
    
    if (HandleIsValid(vertexBufferHandle)) {
        // Success!
    }
    
    ...
}