Let dynamic lights render with r_depthShaders 0

This allows identifying problems with the depth-based light culling.

Author: slipher

src/engine/renderer/tr_backend.cpp

@@ -1212,10 +1212,22 @@ void RB_RunVisTests( )
 
 static void RenderDepthTiles()
 {
-	// 1st step
 	GL_State( GLS_DEPTHTEST_DISABLE );
 	GL_Cull( CT_TWO_SIDED );
 
+	if ( !r_depthShaders.Get() )
+	{
+		// put max range so depth-based planes will always pass in lighttile
+		// setting to 99999 worked on my machines but is technically not allowed by the spec
+		// ARB_color_buffer_float lets you set values outside of [0, 1] but we use
+		// a different extension ARB_texture_float to get float color buffer
+		R_BindFBO( tr.depthtile2FBO );
+		glClearColor( /*max*/ 99999.f, /*min*/ 0.0f, 0.0f, 0.0f );
+		glClear( GL_COLOR_BUFFER_BIT );
+		return;
+	}
+
+	// 1st step
 	R_BindFBO( tr.depthtile1FBO );
 	GL_Viewport( 0, 0, tr.depthtile1FBO->width, tr.depthtile1FBO->height );
 	GL_Scissor( 0, 0, tr.depthtile1FBO->width, tr.depthtile1FBO->height );

src/engine/renderer/tr_local.h

@@ -2683,6 +2683,7 @@ enum
 	extern Cvar::Modified<Cvar::Cvar<std::string>> r_textureMode;
 	extern cvar_t *r_offsetFactor;
 	extern cvar_t *r_offsetUnits;
+	extern Cvar::Cvar<bool> r_depthShaders;
 
 	extern cvar_t *r_physicalMapping;
 	extern cvar_t *r_specularExponentMin;

src/engine/renderer/tr_shader.cpp

@@ -83,9 +83,8 @@ static Cvar::Cvar<float> r_portalDefaultRange(
 	"r_portalDefaultRange", "Default portal range", Cvar::NONE, 1024);
 
 // This can be turned off to debug problems with depth shaders.
-// Almost everything can be rendered correctly without them, except real-time lights
-// (since light tiles are populated using the depth buffer).
-static Cvar::Cvar<bool> r_depthShaders(
+// Things should generally render identically (albeit slower) without them.
+Cvar::Cvar<bool> r_depthShaders(
 	"r_depthShaders", "use depth pre-pass shaders", Cvar::CHEAT, true);
 
 /*