Fix tonemapping availability check

Author: VReaperV

src/engine/renderer/tr_backend.cpp

@@ -3361,14 +3361,15 @@ void RB_CameraPostFX()
 
 	gl_cameraEffectsShader->SetUniform_InverseGamma( 1.0 / r_gamma->value );
 
-	if ( r_highPrecisionRendering.Get() ) {
+	const bool tonemap = r_tonemap.Get() && r_highPrecisionRendering.Get() && glConfig2.textureFloatAvailable;
+	if ( tonemap ) {
 		vec4_t tonemapParms { r_tonemapContrast.Get(), r_tonemapHighlightsCompressionSpeed.Get() };
 		ComputeTonemapParams( tonemapParms[0], tonemapParms[1], r_tonemapHDRMax.Get(),
 			r_tonemapDarkAreaPointHDR.Get(), r_tonemapDarkAreaPointLDR.Get(), tonemapParms[2], tonemapParms[3] );
 		gl_cameraEffectsShader->SetUniform_TonemapParms( tonemapParms );
 		gl_cameraEffectsShader->SetUniform_TonemapExposure( r_tonemapExposure.Get() );
 	}
-	gl_cameraEffectsShader->SetUniform_Tonemap( r_highPrecisionRendering.Get() && r_tonemap.Get() );
+	gl_cameraEffectsShader->SetUniform_Tonemap( tonemap );
 
 	// This shader is run last, so let it render to screen instead of
 	// tr.mainFBO