From: John Tsiombikas <nuclear@mutantstargoat.com>
Date: Tue, 15 Nov 2016 05:13:25 +0000 (+0200)
Subject: do gamma correction on post if we don't have an sRGB framebuffer
X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=laserbrain_demo;a=commitdiff_plain;h=3aacec4aee795e703e8eb9d6852ca47a3be065ee

do gamma correction on post if we don't have an sRGB framebuffer
---

diff --git a/sdr/post_gamma.p.glsl b/sdr/post_gamma.p.glsl
new file mode 100644
index 0000000..6b323f8
--- /dev/null
+++ b/sdr/post_gamma.p.glsl
@@ -0,0 +1,10 @@
+uniform sampler2D tex;
+
+void main()
+{
+	const vec3 invgamma3 = vec3(1.0 / 2.2);
+	vec3 texel = texture2D(tex, gl_TexCoord[0].st).xyz;
+
+	gl_FragColor.rgb = pow(texel, invgamma3);
+	gl_FragColor.a = 1.0;
+}
diff --git a/sdr/post_gamma.v.glsl b/sdr/post_gamma.v.glsl
new file mode 100644
index 0000000..a8fb0cf
--- /dev/null
+++ b/sdr/post_gamma.v.glsl
@@ -0,0 +1,5 @@
+void main()
+{
+	gl_Position = gl_Vertex;
+	gl_TexCoord[0] = gl_MultiTexCoord0;
+}
diff --git a/src/app.cc b/src/app.cc
index d3b5657..096bf4e 100644
--- a/src/app.cc
+++ b/src/app.cc
@@ -12,6 +12,7 @@
 #include "datamap.h"
 #include "ui.h"
 #include "opt.h"
+#include "post.h"
 
 #define NEAR_CLIP	5.0
 #define FAR_CLIP	10000.0
@@ -21,6 +22,7 @@ static void draw_scene();
 long time_msec;
 int win_width, win_height;
 float win_aspect;
+bool fb_srgb;
 bool opt_gear_wireframe;
 
 static float cam_dist = 0.0;
@@ -41,7 +43,7 @@ static bool keystate[256];
 static Mat4 view_matrix, mouse_view_matrix, proj_matrix;
 static TextureSet texman;
 static Scene *scn;
-static unsigned int sdr;
+static unsigned int sdr, sdr_post_gamma;
 
 static long prev_msec;
 
@@ -69,7 +71,12 @@ bool app_init(int argc, char **argv)
 		goatvr_recenter();
 	}
 
+	int srgb_capable;
+	glGetIntegerv(GL_FRAMEBUFFER_SRGB_CAPABLE_EXT, &srgb_capable);
+	printf("Framebuffer %s sRGB-capable\n", srgb_capable ? "is" : "is not");
+	fb_srgb = srgb_capable != 0;
 	glEnable(GL_FRAMEBUFFER_SRGB);
+
 	glEnable(GL_MULTISAMPLE);
 	glEnable(GL_DEPTH_TEST);
 	glEnable(GL_CULL_FACE);
@@ -105,6 +112,10 @@ bool app_init(int argc, char **argv)
 	set_uniform_int(sdr, "texmap", 0);
 	set_uniform_int(sdr, "lightmap", 1);
 
+	if(!fb_srgb) {
+		sdr_post_gamma = create_program_load("sdr/post_gamma.v.glsl", "sdr/post_gamma.p.glsl");
+	}
+
 	glUseProgram(0);
 
 	if(opt.vr || opt.fullscreen) {
@@ -266,6 +277,10 @@ void app_display()
 
 		draw_scene();
 
+		if(!fb_srgb && sdr_post_gamma) {
+			slow_post(sdr_post_gamma);
+			glUseProgram(0);
+		}
 		app_swap_buffers();
 	}
 	assert(glGetError() == GL_NO_ERROR);
@@ -344,6 +359,13 @@ void app_keyboard(int key, bool pressed)
 			}
 			break;
 
+		case 'p':
+			if(mod & MOD_CTRL) {
+				fb_srgb = !fb_srgb;
+				show_message("gamma correction for non-sRGB framebuffers: %s\n", fb_srgb ? "off" : "on");
+			}
+			break;
+
 		case '=':
 			walk_speed *= 1.25;
 			show_message("walk speed: %g", walk_speed);
@@ -370,8 +392,9 @@ void app_mouse_button(int bn, bool pressed, int x, int y)
 
 static inline void mouse_look(int dx, int dy)
 {
-	cam_theta += dx * 0.5;
-	cam_phi += dy * 0.5;
+	float scrsz = (float)win_height;
+	cam_theta += dx * 512.0 / scrsz;
+	cam_phi += dy * 512.0 / scrsz;
 
 	if(cam_phi < -90) cam_phi = -90;
 	if(cam_phi > 90) cam_phi = 90;
diff --git a/src/app.h b/src/app.h
index 02db8db..5e65394 100644
--- a/src/app.h
+++ b/src/app.h
@@ -5,6 +5,7 @@ extern long time_msec;
 extern int win_width, win_height;
 extern float win_aspect;
 extern bool opt_gear_wireframe;
+extern bool fb_srgb;
 
 enum {
 	MOD_SHIFT	= 1,
diff --git a/src/main.cc b/src/main.cc
index 01c9d12..fb8a2e2 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -41,7 +41,11 @@ int main(int argc, char **argv)
 			SDL_Quit();
 			return 1;
 		}
+		fprintf(stderr, "failed to get an sRGB framebuffer.\n");
 	}
+	int val;
+	SDL_GL_GetAttribute(SDL_GL_FRAMEBUFFER_SRGB_CAPABLE, &val);
+	printf("SDL says we %s an sRGB framebuffer\n", val ? "got" : "didn't get");
 
 	if(!(ctx = SDL_GL_CreateContext(win))) {
 		fprintf(stderr, "failed to create OpenGL context\n");
@@ -113,8 +117,11 @@ bool app_is_fullscreen()
 
 void app_grab_mouse(bool grab)
 {
-	SDL_SetWindowGrab(win, grab ? SDL_TRUE : SDL_FALSE);
-	SDL_ShowCursor(grab ? 1 : 0);
+	if(grab) {
+		SDL_WarpMouseInWindow(win, win_width / 2, win_height / 2);
+	}
+	//SDL_SetWindowGrab(win, grab ? SDL_TRUE : SDL_FALSE);
+	//SDL_ShowCursor(grab ? 1 : 0);
 	SDL_SetRelativeMouseMode(grab ? SDL_TRUE : SDL_FALSE);
 	mouse_grabbed = grab;
 }
@@ -164,7 +171,8 @@ static void process_event(SDL_Event *ev)
 
 	case SDL_MOUSEMOTION:
 		if(mouse_grabbed) {
-			app_mouse_delta(ev->motion.xrel, ev->motion.yrel);
+			// XXX xrel/yrel seems faster by default
+			app_mouse_delta(ev->motion.xrel * 0.5, ev->motion.yrel * 0.5);
 		} else {
 			app_mouse_motion(ev->motion.x * scale_factor, ev->motion.y * scale_factor);
 		}
diff --git a/src/post.cc b/src/post.cc
new file mode 100644
index 0000000..b675f5b
--- /dev/null
+++ b/src/post.cc
@@ -0,0 +1,67 @@
+#include "opengl.h"
+#include "app.h"
+
+static void update_fbtex();
+
+static unsigned int fb_tex;
+static int fb_tex_width, fb_tex_height;
+
+void slow_post(unsigned int sdr)
+{
+	update_fbtex();
+
+	glBindTexture(GL_TEXTURE_2D, fb_tex);
+	glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, win_width, win_height);
+
+	glPushAttrib(GL_ENABLE_BIT);
+	glDisable(GL_DEPTH_TEST);
+	glDisable(GL_LIGHTING);
+
+	glUseProgram(sdr);
+
+	float umax = (float)win_width / (float)fb_tex_width;
+	float vmax = (float)win_height / (float)fb_tex_height;
+
+	glBegin(GL_QUADS);
+	glTexCoord2f(0, 0);
+	glVertex2f(-1, -1);
+	glTexCoord2f(umax, 0);
+	glVertex2f(1, -1);
+	glTexCoord2f(umax, vmax);
+	glVertex2f(1, 1);
+	glTexCoord2f(0, vmax);
+	glVertex2f(-1, 1);
+	glEnd();
+
+	glPopAttrib();
+}
+
+static int next_pow2(int x)
+{
+	x--;
+	x = (x >> 1) | x;
+	x = (x >> 2) | x;
+	x = (x >> 4) | x;
+	x = (x >> 8) | x;
+	x = (x >> 16) | x;
+	return x + 1;
+}
+
+static void update_fbtex()
+{
+	if(win_width <= fb_tex_width && win_height <= fb_tex_height) {
+		return;		// nothing to do
+	}
+	if(!fb_tex) {
+		glGenTextures(1, &fb_tex);
+		glBindTexture(GL_TEXTURE_2D, fb_tex);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+	} else {
+		glBindTexture(GL_TEXTURE_2D, fb_tex);
+	}
+
+	fb_tex_width = next_pow2(win_width);
+	fb_tex_height = next_pow2(win_height);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, fb_tex_width, fb_tex_height, 0, GL_RGB, GL_UNSIGNED_BYTE, 0);
+}
diff --git a/src/post.h b/src/post.h
new file mode 100644
index 0000000..737cb02
--- /dev/null
+++ b/src/post.h
@@ -0,0 +1,6 @@
+#ifndef POST_H_
+#define POST_H_
+
+void slow_post(unsigned int sdr);
+
+#endif	// POST_H_