Render Texture

A RenderTexture lets you render a scene (or part of it) to an off-screen texture instead of the screen. This is useful for minimaps, mirrors, portals, post-processing inputs, and any effect that requires capturing rendered output.

Creating a RenderTexture

import { RenderTexture, type RenderTextureHandle } from 'esengine';

const rt: RenderTextureHandle = RenderTexture.create({
    width: 512,
    height: 512,
    depth: true,
    filter: 'linear',
});

RenderTextureOptions

Field	Type	Default	Description
width	number	—	Texture width in pixels
height	number	—	Texture height in pixels
depth	boolean	false	Attach a depth buffer
filter	'nearest' | 'linear'	'nearest'	Texture filtering mode

Rendering to Texture

Wrap your draw calls between begin() and end(). Everything rendered in between goes to the texture instead of the screen:

import { RenderTexture, Draw } from 'esengine';

RenderTexture.begin(rt, viewProjectionMatrix);

Draw.rect(0, 0, 100, 100, { r: 1, g: 0, b: 0, a: 1 });

RenderTexture.end();

The viewProjection parameter is a Float32Array containing the 4x4 view-projection matrix that defines the camera for this off-screen render pass.

Note

begin() sets the render target and viewport. end() restores the previous render target. Always call end() after begin().

Using the Result

After rendering, rt.textureId holds the GPU texture ID. Use it anywhere a texture is expected:

import { Draw, Sprite } from 'esengine';

Draw.texture(rt.textureId, 0, 0, rt.width, rt.height);

You can also assign it to a Sprite’s texture for entity-based rendering.

Depth Texture

If the RenderTexture was created with depth: true, retrieve the depth texture for effects like shadow mapping:

const depthTextureId = RenderTexture.getDepthTexture(rt);

Lifecycle

Resizing

When the target resolution changes (e.g. window resize), resize the RenderTexture:

const resized = RenderTexture.resize(rt, newWidth, newHeight);

resize() returns a new RenderTextureHandle. Use the returned handle going forward.

Releasing

Release GPU resources when the RenderTexture is no longer needed:

RenderTexture.release(rt);

API Reference

Method	Returns	Description
RenderTexture.create(options)	RenderTextureHandle	Create a new render texture
RenderTexture.begin(rt, viewProjection)	void	Begin rendering to texture
RenderTexture.end()	void	End rendering to texture
RenderTexture.getDepthTexture(rt)	number	Get depth texture ID
RenderTexture.resize(rt, width, height)	RenderTextureHandle	Resize render texture
RenderTexture.release(rt)	void	Release GPU resources

RenderTextureHandle

Field	Type	Description
textureId	number	GPU texture ID for the color attachment
width	number	Current width in pixels
height	number	Current height in pixels

Next Steps

• Custom Draw — immediate-mode drawing API
• Post-Processing — full-screen effects
• Materials & Shaders — custom shaders