GL3: Square particles with cvar gl3_particle_square

if that cvar is set to 1, particles aren't rendered as nice circles, but
as squares, like in the software renderer or in Quake1.

Also documented it in cvarlist.md and fixed some typos there

src/client/refresh/gl3/gl3_main.c

@@ -96,6 +96,7 @@ cvar_t *gl_drawbuffer;
 cvar_t *gl_clear;
 cvar_t *gl3_particle_size;
 cvar_t *gl3_particle_fade_factor;
+cvar_t *gl3_particle_square;
 
 cvar_t *gl_lefthand;
 cvar_t *gl_farsee;
@@ -208,6 +209,7 @@ GL3_Register(void)
 	gl_customheight = ri.Cvar_Get("gl_customheight", "768", CVAR_ARCHIVE);
 	gl3_particle_size = ri.Cvar_Get("gl3_particle_size", "40", CVAR_ARCHIVE);
 	gl3_particle_fade_factor = ri.Cvar_Get("gl3_particle_fade_factor", "1.2", CVAR_ARCHIVE);
+	gl3_particle_square = ri.Cvar_Get("gl3_particle_square", "0", CVAR_ARCHIVE);
 
 	gl_norefresh = ri.Cvar_Get("gl_norefresh", "0", 0);
 	gl_drawentities = ri.Cvar_Get("gl_drawentities", "1", 0);
@@ -1655,6 +1657,12 @@ GL3_BeginFrame(float camera_separation)
 		GL3_UpdateUBO3D();
 	}
 
+	if(gl3_particle_square->modified)
+	{
+		gl3_particle_square->modified = false;
+		GL3_RecreateShaders();
+	}
+
 
 	/* go into 2D mode */
 

src/client/refresh/gl3/gl3_shaders.c

@@ -689,6 +689,18 @@ static const char* fragmentSrcParticles = MULTILINE_STRING(
 		}
 );
 
+static const char* fragmentSrcParticlesSquare = MULTILINE_STRING(
+
+		// it gets attributes and uniforms from fragmentCommon3D
+
+		in vec4 passColor;
+
+		void main()
+		{
+			outColor = passColor;
+		}
+);
+
 
 #undef MULTILINE_STRING
 
@@ -977,10 +989,8 @@ static void initUBOs(void)
 	gl3state.currentUBO = gl3state.uniLightsUBO;
 }
 
-qboolean GL3_InitShaders(void)
+static qboolean createShaders(void)
 {
-	initUBOs();
-
 	if(!initShader2D(&gl3state.si2D, vertexSrc2D, fragmentSrc2D))
 	{
 		R_Printf(PRINT_ALL, "WARNING: Failed to create shader program for textured 2D rendering!\n");
@@ -1053,7 +1063,14 @@ qboolean GL3_InitShaders(void)
 		R_Printf(PRINT_ALL, "WARNING: Failed to create shader program for rendering flat-colored models!\n");
 		return false;
 	}
-	if(!initShader3D(&gl3state.siParticle, vertexSrcParticles, fragmentSrcParticles))
+
+	const char* particleFrag = fragmentSrcParticles;
+	if(gl3_particle_square->value != 0.0f)
+	{
+		particleFrag = fragmentSrcParticlesSquare;
+	}
+
+	if(!initShader3D(&gl3state.siParticle, vertexSrcParticles, particleFrag))
 	{
 		R_Printf(PRINT_ALL, "WARNING: Failed to create shader program for rendering particles!\n");
 		return false;
@@ -1064,21 +1081,40 @@ qboolean GL3_InitShaders(void)
 	return true;
 }
 
-void GL3_ShutdownShaders(void)
+qboolean GL3_InitShaders(void)
+{
+	initUBOs();
+
+	return createShaders();
+}
+
+static void deleteShaders(void)
 {
 	const gl3ShaderInfo_t siZero = {0};
 	for(gl3ShaderInfo_t* si = &gl3state.si2D; si <= &gl3state.siParticle; ++si)
 	{
 		if(si->shaderProgram != 0)  glDeleteProgram(si->shaderProgram);
 		*si = siZero;
 	}
+}
+
+void GL3_ShutdownShaders(void)
+{
+	deleteShaders();
 
 	// let's (ab)use the fact that all 4 UBO handles are consecutive fields
 	// of the gl3state struct
 	glDeleteBuffers(4, &gl3state.uniCommonUBO);
 	gl3state.uniCommonUBO = gl3state.uni2DUBO = gl3state.uni3DUBO = gl3state.uniLightsUBO = 0;
 }
 
+qboolean GL3_RecreateShaders(void)
+{
+	// delete and recreate the existing shaders (but not the UBOs)
+	deleteShaders();
+	return createShaders();
+}
+
 static inline void
 updateUBO(GLuint ubo, GLsizeiptr size, void* data)
 {

src/client/refresh/gl3/header/local.h

@@ -468,6 +468,7 @@ extern void GL3_ShutdownMeshes(void);
 
 // gl3_shaders.c
 
+extern qboolean GL3_RecreateShaders(void);
 extern qboolean GL3_InitShaders(void);
 extern void GL3_ShutdownShaders(void);
 extern void GL3_UpdateUBOCommon(void);
@@ -507,6 +508,7 @@ extern cvar_t *gl_anisotropic;
 extern cvar_t *gl_lightlevel;
 extern cvar_t *gl3_overbrightbits;
 extern cvar_t *gl3_particle_fade_factor;
+extern cvar_t *gl3_particle_square;
 
 extern cvar_t *gl_modulate;
 extern cvar_t *gl_lightmap;

stuff/cvarlist.md

@@ -13,7 +13,8 @@ General:
 
 * **basedir**: Directory from which the game data is loaded. Can be used
   in startup scripts, to test binaries, etc. If not set, the directory
-  containing the binaries is used.
+  containing the binaries is used.  
+  To use this cvar, set it at startup, like `./quake2 +set basedir /path/to/quake2`
 
 * **cl_async**: If set to `1` (the default) the client is asynchronous.
   The client framerate is fixed, the renderer framerate is variable.
@@ -76,7 +77,7 @@ Graphics (all renderers):
   with an aspect ratio of 4:3, regardless what the actual windows size
   or resolution is.
 
-* **cl_gun**: Decides weather the gun is drawn. If set to `0` the gun
+* **cl_gun**: Decides whether the gun is drawn. If set to `0` the gun
   is omitted. If set to `1` the gun is only drawn if the FOV is equal
   or smaller than 90. This was the default with Vanilla Quake II. If set
   to `2` the gun is drawn regardless of the FOV. This is the default
@@ -126,8 +127,8 @@ Graphics (all renderers):
 
 * **gl_msaa_samples**: Full scene anti aliasing samples. The number of
   samples depends on the GPU driver, most drivers support at least
-  `2`, `4` and `8` samples. If an invalid value is set the value is
-  reverted the highest number of samples supported. Especially on OpenGL
+  `2`, `4` and `8` samples. If an invalid value is set, the value is
+  reverted to the highest number of samples supported. Especially on OpenGL
   3.2 anti aliasing is expensive and can lead to a huge performance hit,
   so try setting it to a lower value if your framerate is too low.
 
@@ -192,3 +193,8 @@ Graphics (GL3 only):
 * **gl3_particle_fade_factor**: "softness" of particles: higher values
   look less soft. Defaults to `1.2`.  
   A value of `10` looks similar to the GL1 particles.
+
+* **gl3_particle_square**: If set to `1`, particles are rendered as squares,
+  like in the old software renderer or Quake1. Default is `0`.
+
+