kemena::kOffscreenRenderer Class Reference

Renders to an offscreen FBO for thumbnails, previews, and image export. More...

#include <koffscreenrenderer.h>

Public Member Functions
	kOffscreenRenderer (int width=256, int height=256)
	Construct the renderer and allocate its offscreen FBO.
	~kOffscreenRenderer ()
	Destroy the renderer and release all GPU resources (FBO, textures, shaders).
void	resize (int newWidth, int newHeight)
	Resize the offscreen buffer.
void	setBackgroundColor (kVec4 color)
	Set the background clear color and alpha (default: opaque dark grey).
kVec4	getBackgroundColor () const
	Get the current background clear color and alpha.
void	render (kWorld *world, kScene *scene, kCamera *camera)
	Render the full scene to the offscreen buffer.
void	renderMesh (kMesh *mesh, kCamera *camera=nullptr)
	Render a single mesh to the offscreen buffer.
void	renderMeshWithMaterial (kMesh *mesh, kCamera *camera=nullptr)
	Render a mesh using its assigned material shader and uniforms.
uint32_t	getTexture () const
	GPU texture ID of the current render result.
int	getWidth () const
	Get the output texture width in pixels.
int	getHeight () const
	Get the output texture height in pixels.
bool	saveToFile (const kString &filePath) const
	Save the current render result to an image file.

Detailed Description

Renders to an offscreen FBO for thumbnails, previews, and image export.

Usage:

kOffscreenRenderer offscreen(256, 256);
 
// Full scene render from a custom camera
offscreen.render(world, scene, &myCamera);
 
// Single mesh with auto-framed camera
offscreen.renderMesh(mesh);
 
// Use as ImGui thumbnail
ImGui::Image((ImTextureID)(uintptr_t)offscreen.getTexture(), {256, 256});
 
// Save to file
offscreen.saveToFile("thumbnail.png");

Constructor & Destructor Documentation

kOffscreenRenderer()

kemena::kOffscreenRenderer::kOffscreenRenderer	(	int	width = 256,
		int	height = 256 )

Construct the renderer and allocate its offscreen FBO.

Parameters

width	Output texture width in pixels.
height	Output texture height in pixels.

~kOffscreenRenderer()

kemena::kOffscreenRenderer::~kOffscreenRenderer

(

)

Destroy the renderer and release all GPU resources (FBO, textures, shaders).

Member Function Documentation

getBackgroundColor()

kVec4 kemena::kOffscreenRenderer::getBackgroundColor ( ) const

inline

Get the current background clear color and alpha.

Returns

The RGBA background color.

getHeight()

int kemena::kOffscreenRenderer::getHeight ( ) const

inline

Get the output texture height in pixels.

Returns

Buffer height.

getTexture()

uint32_t kemena::kOffscreenRenderer::getTexture ( ) const

inline

GPU texture ID of the current render result.

Pass directly to ImGui::Image as (ImTextureID)(uintptr_t)getTexture(). Valid until the next resize() call.

getWidth()

int kemena::kOffscreenRenderer::getWidth ( ) const

inline

Get the output texture width in pixels.

Returns

Buffer width.

render()

void kemena::kOffscreenRenderer::render	(	kWorld *	world,
		kScene *	scene,
		kCamera *	camera )

Render the full scene to the offscreen buffer.

Uses the provided camera for view/projection. All scene lights, materials, and textures are applied. Shadows are not included.

Parameters

world	World (used only for skinning state, may be nullptr).
scene	Scene to render.
camera	Camera defining the viewpoint.

renderMesh()

void kemena::kOffscreenRenderer::renderMesh	(	kMesh *	mesh,
		kCamera *	camera = nullptr )

Render a single mesh to the offscreen buffer.

If camera is nullptr, a camera is auto-positioned to frame the mesh's world AABB from a 3/4 view angle.

A simple three-point directional light setup is used. The mesh's own material and shader are applied if present.

Parameters

mesh	Mesh to render (must be loaded and have a material).
camera	Override camera, or nullptr for auto-framing.

renderMeshWithMaterial()

void kemena::kOffscreenRenderer::renderMeshWithMaterial	(	kMesh *	mesh,
		kCamera *	camera = nullptr )

Render a mesh using its assigned material shader and uniforms.

Unlike renderMesh(), which uses the built-in preview shader, this method binds the mesh's own kMaterial and kShader so that material properties (diffuse, metallic, textures, etc.) are visible in the result. A simple sun light is injected so the result is shaded.

The mesh must have a material with a compiled shader; if not, nothing is drawn.

Parameters

mesh	Mesh to render.
camera	Override camera, or nullptr for auto-framing.

resize()

void kemena::kOffscreenRenderer::resize	(	int	newWidth,
		int	newHeight )

Resize the offscreen buffer.

Destroys and recreates the FBO. Any previous render result is lost.

Parameters

newWidth	New output texture width in pixels.
newHeight	New output texture height in pixels.

saveToFile()

bool kemena::kOffscreenRenderer::saveToFile

(

const kString &

filePath

)

const

Save the current render result to an image file.

The format is determined by the file extension: .png — lossless, recommended .jpg — lossy, smaller .bmp — uncompressed .tga — uncompressed with alpha

Parameters

filePath

Destination path including extension.

Returns

true on success.

setBackgroundColor()

void kemena::kOffscreenRenderer::setBackgroundColor ( kVec4 color )

inline

Set the background clear color and alpha (default: opaque dark grey).

Set alpha to 0 for a fully transparent background — useful when compositing the thumbnail over other UI elements.

Parameters

color

RGBA clear color in linear/normalized [0,1] components.

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

• Source/include/koffscreenrenderer.h