WebGLRenderer: Revert to drawingbuffer sized transmissionRenderTarget (#26138)

* Revert "WebGLRenderer: Add pixelRatio to transmissionRenderTarget. (#26131)"

This reverts commit d283449222f07bc7d122d2e94d0364f1c8ac84c1.

* Revert "WebGLRenderer: Restore POT for transmission render target. (#25494)"

* WebGLRenderer: Fixed missing import.

* Clean up.

* Updated screenshots.

src/renderers/WebGLRenderer.js

@@ -25,8 +25,10 @@ import {
 import { Color } from '../math/Color.js';
 import { Frustum } from '../math/Frustum.js';
 import { Matrix4 } from '../math/Matrix4.js';
+import { Vector2 } from '../math/Vector2.js';
 import { Vector3 } from '../math/Vector3.js';
 import { Vector4 } from '../math/Vector4.js';
+import { floorPowerOfTwo } from '../math/MathUtils.js';
 import { WebGLAnimation } from './webgl/WebGLAnimation.js';
 import { WebGLAttributes } from './webgl/WebGLAttributes.js';
 import { WebGLBackground } from './webgl/WebGLBackground.js';
@@ -208,6 +210,7 @@ class WebGLRenderer {
 
 		const _projScreenMatrix = new Matrix4();
 
+		const _vector2 = new Vector2();
 		const _vector3 = new Vector3();
 
 		const _emptyScene = { background: null, fog: null, environment: null, overrideMaterial: null, isScene: true };
@@ -1334,11 +1337,11 @@ class WebGLRenderer {
 
 		function renderTransmissionPass( opaqueObjects, transmissiveObjects, scene, camera ) {
 
-			if ( _transmissionRenderTarget === null ) {
+			const isWebGL2 = capabilities.isWebGL2;
 
-				const isWebGL2 = capabilities.isWebGL2;
+			if ( _transmissionRenderTarget === null ) {
 
-				_transmissionRenderTarget = new WebGLRenderTarget( 1024 * _pixelRatio, 1024 * _pixelRatio, {
+				_transmissionRenderTarget = new WebGLRenderTarget( 1, 1, {
 					generateMipmaps: true,
 					type: extensions.has( 'EXT_color_buffer_half_float' ) ? HalfFloatType : UnsignedByteType,
 					minFilter: LinearMipmapLinearFilter,
@@ -1357,6 +1360,18 @@ class WebGLRenderer {
 
 			}
 
+			_this.getDrawingBufferSize( _vector2 );
+
+			if ( isWebGL2 ) {
+
+				_transmissionRenderTarget.setSize( _vector2.x, _vector2.y );
+
+			} else {
+
+				_transmissionRenderTarget.setSize( floorPowerOfTwo( _vector2.x ), floorPowerOfTwo( _vector2.y ) );
+
+			}
+
 			//
 
 			const currentRenderTarget = _this.getRenderTarget();