public override void OnLoad(GameState state)
{
base.OnLoad(state);
//a vertex buffer is an array of vertices within video memory
//
//In this test we allocate a VertexBuffer directly. However, for performance in-game we use a Pool<VertexBuffer>
//to request/release VertexBuffers. Pooling vertexbuffers allows us to recycle buffers rather than wasting time
//destroying and allocating them.
VertexBuffer buffer = VertexBuffer.Allocate();
//in order for openGL to know the size and structure of our vertex components, we associate
//an array of VertexAttributes to our buffer. each element of the array specifies a component
//of a vertex within the buffer.
AttributedVertexBuffer aBuffer = new AttributedVertexBuffer(buffer, Util.vector2Attributes);
//for vertex types defined within the engine, the VertexAttribute array that describes the struct layout
//is specified as a static variable on the struct named vAttributes. Util class
//holds vertex attributes for OpenTK types
//
//in the future it would be nice if this step is automatically handled somewhere in the engine. Unfortunately,
//since interfaces cannot have static members we would have to use reflection libraries to auto-generate VertexAttributes.
//we use a loader to load vertices into an vertex buffer.
VertexLoader <Vector2> loader = new VertexLoader <Vector2>(BufferUsageHint.DynamicDraw, aBuffer);
//For VertexLoader, we must manually specify attributes for the buffer. However, higher-level loaders
//such as SpriteLoader will automatically associate attributes to the buffer.
//
//the "dynamic draw" usage hint tells openGL that we only intend to write data to the buffer.
//the usage hint only affects the performance of the buffer, not its behavior.
//add a triangle.
loader.AddVertexSet(
PrimitiveType.Triangles,
new[] {
new Vector2(0, 0), //for simple position vertices, we use Vector2 struct from OpenTK library.
new Vector2(0, 1), //
new Vector2(1, 1) //for textured vertices we would use the engine's TexturedVertex2 struct
});
//add a second triangle
loader.AddVertexSet(
PrimitiveType.Triangles,
new[] {
new Vector2(0, 0),
new Vector2(0, -1),
new Vector2(-1, -1)
});
//once all the vertices have been added to the loader, we load the vertex buffer
loadedVertexSets = loader.Load();
//The result is an enumeration of VertexSet objects, which represents
//a drawable set of vertices within the vertex buffer.
//In this test, a VertexSet represents a single 2D triangle.
}
public override void OnLoad(GameState state)
{
base.OnLoad(state);
//a vertex buffer is an array of vertices within video memory
//
//In this test we allocate a VertexBuffer directly. However, for performance in-game we use a Pool<VertexBuffer>
//to request/release VertexBuffers. Pooling vertexbuffers allows us to recycle buffers rather than wasting time
//destroying and allocating them.
VertexBuffer buffer = VertexBuffer.Allocate();
//in order for openGL to know the size and structure of our vertex components, we associate
//an array of VertexAttributes to our buffer. each element of the array specifies a component
//of a vertex within the buffer.
AttributedVertexBuffer aBuffer = new AttributedVertexBuffer(buffer, Util.vector2Attributes);
//for vertex types defined within the engine, the VertexAttribute array that describes the struct layout
//is specified as a static variable on the struct named vAttributes. Util class
//holds vertex attributes for OpenTK types
//
//in the future it would be nice if this step is automatically handled somewhere in the engine. Unfortunately,
//since interfaces cannot have static members we would have to use reflection libraries to auto-generate VertexAttributes.
//we use a loader to load vertices into an vertex buffer.
VertexLoader<Vector2> loader = new VertexLoader<Vector2>(BufferUsageHint.DynamicDraw, aBuffer);
//For VertexLoader, we must manually specify attributes for the buffer. However, higher-level loaders
//such as SpriteLoader will automatically associate attributes to the buffer.
//
//the "dynamic draw" usage hint tells openGL that we only intend to write data to the buffer.
//the usage hint only affects the performance of the buffer, not its behavior.
//add a triangle.
loader.AddVertexSet(
PrimitiveType.Triangles,
new[] {
new Vector2(0, 0), //for simple position vertices, we use Vector2 struct from OpenTK library.
new Vector2(0, 1), //
new Vector2(1, 1) //for textured vertices we would use the engine's TexturedVertex2 struct
});
//add a second triangle
loader.AddVertexSet(
PrimitiveType.Triangles,
new[] {
new Vector2(0, 0),
new Vector2(0, -1),
new Vector2(-1, -1)
});
//once all the vertices have been added to the loader, we load the vertex buffer
loadedVertexSets = loader.Load();
//The result is an enumeration of VertexSet objects, which represents
//a drawable set of vertices within the vertex buffer.
//In this test, a VertexSet represents a single 2D triangle.
}
