New gamma correction implementation using glsl. Enabled by default on OpenGL2. Disable with -noglslgamma.

Avoids general bugginess of hardware gamma, doesn't affect the whole screen in windowed mode like HW gamma. Should fix http://sourceforge.net/p/quakespasm/bugs/5/

git-svn-id: svn+ssh://svn.code.sf.net/p/quakespasm/code/trunk@1157 af15c1b1-3010-417e-b628-4374ebc0bcbd

Author: ewasylishen

quakespasm/Quake/gl_rmain.c

@@ -103,6 +103,140 @@ cvar_t	gl_zfix = {"gl_zfix", "0", CVAR_NONE}; // QuakeSpasm z-fighting fix
 
 qboolean r_drawflat_cheatsafe, r_fullbright_cheatsafe, r_lightmap_cheatsafe, r_drawworld_cheatsafe; //johnfitz
 
+//==============================================================================
+//
+// GLSL GAMMA CORRECTION
+//
+//==============================================================================
+
+static GLuint r_gamma_texture;
+static GLuint r_gamma_program;
+
+// uniforms used in gamma shader
+static GLuint gammaLoc;
+static GLuint textureLoc;
+
+/*
+=============
+GLSLGamma_DeleteTexture
+=============
+*/
+void GLSLGamma_DeleteTexture (void)
+{
+	glDeleteTextures (1, &r_gamma_texture);
+	r_gamma_texture = 0;
+	r_gamma_program = 0; // deleted in R_DeleteShaders
+}
+
+/*
+=============
+GLSLGamma_CreateShaders
+=============
+*/
+static void GLSLGamma_CreateShaders (void)
+{
+	const GLchar *vertSource = \
+		"#version 110\n"
+		"\n"
+		"void main(void) {\n"
+		"	gl_Position = vec4(gl_Vertex.xy, 0.0, 1.0);\n"
+		"	gl_TexCoord[0] = gl_MultiTexCoord0;\n"
+		"}\n";
+
+	const GLchar *fragSource = \
+		"#version 110\n"
+		"\n"
+		"uniform sampler2D GammaTexture;\n"
+		"uniform float GammaValue;\n"
+		"\n"
+		"void main(void) {\n"
+		"	  vec4 frag = texture2D(GammaTexture, gl_TexCoord[0].xy);\n"
+		"	  gl_FragColor = vec4(pow(frag.rgb, vec3(GammaValue)), 1.0);\n"
+		"}\n";
+
+	if (!gl_glsl_gamma_able)
+		return;
+
+	r_gamma_program = GL_CreateProgram (vertSource, fragSource, 0, NULL);
+
+// get uniform locations
+	gammaLoc = GL_GetUniformLocation (&r_gamma_program, "GammaValue");
+	textureLoc = GL_GetUniformLocation (&r_gamma_program, "GammaTexture");
+}
+
+/*
+=============
+GLSLGamma_GammaCorrect
+=============
+*/
+void GLSLGamma_GammaCorrect (void)
+{
+	if (!gl_glsl_gamma_able)
+		return;
+
+	if (vid_gamma.value == 1)
+		return;
+
+// create render-to-texture texture if needed
+	if (!r_gamma_texture)
+	{
+		glGenTextures (1, &r_gamma_texture);
+		glBindTexture (GL_TEXTURE_2D, r_gamma_texture);
+	
+		glTexImage2D (GL_TEXTURE_2D, 0, GL_RGBA8, glwidth, glheight, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);
+		glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+		glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	}
+
+// create shader if needed
+	if (!r_gamma_program)
+	{
+		GLSLGamma_CreateShaders ();
+		if (!r_gamma_program)
+		{
+			Sys_Error("GLSLGamma_CreateShaders failed");
+		}
+	}
+	
+// copy the framebuffer to the texture
+	GL_DisableMultitexture();
+	glBindTexture (GL_TEXTURE_2D, r_gamma_texture);
+	glCopyTexSubImage2D (GL_TEXTURE_2D, 0, 0, 0, glx, gly, glwidth, glheight);
+
+	glClear (GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
+
+// draw the texture back to the framebuffer with a fragment shader
+	GL_UseProgramFunc (r_gamma_program);
+	GL_Uniform1fFunc (gammaLoc, vid_gamma.value);
+	GL_Uniform1iFunc (textureLoc, 0); // use texture unit 0
+
+	glDisable (GL_ALPHA_TEST);
+	glDisable (GL_DEPTH_TEST);
+
+	glViewport (glx, gly, glwidth, glheight);
+	glMatrixMode (GL_PROJECTION);
+	glLoadIdentity ();
+	glOrtho (0, 1, 1, 0, -99999, 99999);
+	glMatrixMode (GL_MODELVIEW);
+	glLoadIdentity ();
+
+	glBegin (GL_QUADS);
+	glTexCoord2f (0, 0);
+	glVertex2f (-1, -1);
+	glTexCoord2f (1, 0);
+	glVertex2f (1, -1);
+	glTexCoord2f (1, 1);
+	glVertex2f (1, 1);
+	glTexCoord2f (0, 1);
+	glVertex2f (-1, 1);
+	glEnd ();
+	
+	GL_UseProgramFunc (0);
+	
+// clear cached binding
+	GL_Bind (notexture);
+}
+
 /*
 =================
 R_CullBox -- johnfitz -- replaced with new function from lordhavoc

quakespasm/Quake/gl_screen.c

@@ -1077,6 +1077,8 @@ void SCR_UpdateScreen (void)
 
 	V_UpdateBlend (); //johnfitz -- V_UpdatePalette cleaned up and renamed
 
+	GLSLGamma_GammaCorrect ();
+
 	GL_EndRendering ();
 }
 

quakespasm/Quake/gl_vidsdl.c

@@ -102,6 +102,7 @@ qboolean gl_texture_NPOT = false; //ericw
 qboolean gl_vbo_able = false; //ericw
 qboolean gl_glsl_able = false; //ericw
 GLint gl_max_texture_units = 0; //ericw
+qboolean gl_glsl_gamma_able = false; //ericw
 
 PFNGLMULTITEXCOORD2FARBPROC GL_MTexCoord2fFunc = NULL; //johnfitz
 PFNGLACTIVETEXTUREARBPROC GL_SelectTextureFunc = NULL; //johnfitz
@@ -177,6 +178,9 @@ VID_Gamma_SetGamma -- apply gamma correction
 */
 static void VID_Gamma_SetGamma (void)
 {
+	if (gl_glsl_gamma_able)
+		return;
+
 	if (draw_context && gammaworks)
 	{
 		float	value;
@@ -213,6 +217,9 @@ VID_Gamma_Restore -- restore system gamma
 */
 static void VID_Gamma_Restore (void)
 {
+	if (gl_glsl_gamma_able)
+		return;
+
 	if (draw_context && gammaworks)
 	{
 #if defined(USE_SDL2)
@@ -252,6 +259,9 @@ VID_Gamma_f -- callback when the cvar changes
 */
 static void VID_Gamma_f (cvar_t *var)
 {
+	if (gl_glsl_gamma_able)
+		return;
+
 #if USE_GAMMA_RAMPS
 	int i;
 
@@ -273,6 +283,12 @@ VID_Gamma_Init -- call on init
 */
 static void VID_Gamma_Init (void)
 {
+	Cvar_RegisterVariable (&vid_gamma);
+	Cvar_SetCallback (&vid_gamma, VID_Gamma_f);
+
+	if (gl_glsl_gamma_able)
+		return;
+
 #if defined(USE_SDL2)
 # if USE_GAMMA_RAMPS
 	gammaworks	= (SDL_GetWindowGammaRamp(draw_context, vid_sysgamma_red, vid_sysgamma_green, vid_sysgamma_blue) == 0);
@@ -293,9 +309,6 @@ static void VID_Gamma_Init (void)
 
 	if (!gammaworks)
 		Con_SafePrintf("gamma adjustment not available\n");
-
-	Cvar_RegisterVariable (&vid_gamma);
-	Cvar_SetCallback (&vid_gamma, VID_Gamma_f);
 }
 
 /*
@@ -683,6 +696,8 @@ static void VID_Restart (void)
 // memory leak.
 
 	TexMgr_DeleteTextureObjects ();
+	GLSLGamma_DeleteTexture ();
+	R_DeleteShaders ();
 
 //
 // set new mode
@@ -1096,6 +1111,19 @@ static void GL_CheckExtensions (void)
 	{
 		Con_Warning ("OpenGL version < 2, GLSL not available\n");
 	}
+	
+	// GLSL gamma
+	//
+	if (COM_CheckParm("-noglslgamma"))
+		Con_Warning ("GLSL gamma disabled at command line\n");
+	else if (gl_glsl_able && gl_texture_NPOT)
+	{
+		gl_glsl_gamma_able = true;
+	}
+	else
+	{
+		Con_Warning ("GLSL gamma not available, using hardware gamma\n");
+	}
 }
 
 /*
@@ -1168,7 +1196,6 @@ static void GL_Init (void)
 	}
 	//johnfitz
 
-	R_DeleteShaders ();
 	GLAlias_CreateShaders ();
 	GL_ClearBufferBindings ();	
 }

quakespasm/Quake/glquake.h

@@ -222,6 +222,7 @@ extern QS_PFNGLUNIFORM1FPROC GL_Uniform1fFunc;
 extern QS_PFNGLUNIFORM3FPROC GL_Uniform3fFunc;
 extern QS_PFNGLUNIFORM4FPROC GL_Uniform4fFunc;
 extern	qboolean	gl_glsl_able;
+extern	qboolean	gl_glsl_gamma_able;
 // ericw --
 
 //ericw -- NPOT texture support
@@ -376,5 +377,9 @@ void R_DrawWorld_Water (void);
 
 void GL_BindBuffer (GLenum target, GLuint buffer);
 void GL_ClearBufferBindings ();
+
+void GLSLGamma_DeleteTexture (void);
+void GLSLGamma_GammaCorrect (void);
+
 #endif	/* __GLQUAKE_H */