DrawList.go

package imgui

// #include "DrawListWrapper.h"
import "C"
import "unsafe"

// DrawList is a draw-command list.
// This is the low-level list of polygons that ImGui functions are filling.
// At the end of the frame, all command lists are passed to your render function for rendering.
//
// Each ImGui window contains its own DrawList. You can use GetWindowDrawList() to access
// the current window draw list and draw custom primitives.
//
// You can interleave normal ImGui calls and adding primitives to the current draw list.
//
// All positions are generally in pixel coordinates (top-left at (0,0), bottom-right at io.DisplaySize),
// however you are totally free to apply whatever transformation matrix to want to the data
// (if you apply such transformation you'll want to apply it to ClipRect as well)
//
// Important: Primitives are always added to the list and not culled (culling is done at
// higher-level by ImGui functions), if you use this API a lot consider coarse culling your drawn objects.
type DrawList uintptr

func (list DrawList) handle() C.IggDrawList {
	return C.IggDrawList(list)
}

// Commands returns the list of draw commands.
// Typically 1 command = 1 GPU draw call, unless the command is a callback.
func (list DrawList) Commands() []DrawCommand {
	count := int(C.iggDrawListGetCommandCount(list.handle()))
	commands := make([]DrawCommand, count)
	for i := 0; i < count; i++ {
		commands[i] = DrawCommand(C.iggDrawListGetCommand(list.handle(), C.int(i)))
	}
	return commands
}

// VertexBufferLayout returns the byte sizes necessary to select fields in a vertex buffer of a DrawList.
func VertexBufferLayout() (entrySize int, posOffset int, uvOffset int, colOffset int) {
	var entrySizeArg C.size_t
	var posOffsetArg C.size_t
	var uvOffsetArg C.size_t
	var colOffsetArg C.size_t
	C.iggGetVertexBufferLayout(&entrySizeArg, &posOffsetArg, &uvOffsetArg, &colOffsetArg)
	entrySize = int(entrySizeArg)
	posOffset = int(posOffsetArg)
	uvOffset = int(uvOffsetArg)
	colOffset = int(colOffsetArg)
	return
}

// VertexBuffer returns the handle information of the whole vertex buffer.
// Returned are the handle pointer and the total byte size.
// The buffer is a packed array of vertex entries, each consisting of a 2D position vector, a 2D UV vector,
// and a 4-byte color value. To determine the byte size and offset values, call VertexBufferLayout.
func (list DrawList) VertexBuffer() (unsafe.Pointer, int) {
	var data unsafe.Pointer
	var size C.int

	C.iggDrawListGetRawVertexBuffer(list.handle(), &data, &size)

	return data, int(size)
}

// IndexBufferLayout returns the byte size necessary to select fields in an index buffer of DrawList.
func IndexBufferLayout() (entrySize int) {
	var entrySizeArg C.size_t
	C.iggGetIndexBufferLayout(&entrySizeArg)
	entrySize = int(entrySizeArg)
	return
}

// IndexBuffer returns the handle information of the whole index buffer.
// Returned are the handle pointer and the total byte size.
// The buffer is a packed array of index entries, each consisting of an integer offset.
// To determine the byte size, call IndexBufferLayout.
func (list DrawList) IndexBuffer() (unsafe.Pointer, int) {
	var data unsafe.Pointer
	var size C.int

	C.iggDrawListGetRawIndexBuffer(list.handle(), &data, &size)

	return data, int(size)
}