From: John Tsiombikas <nuclear@member.fsf.org>
Date: Tue, 8 Dec 2020 00:49:11 +0000 (+0200)
Subject: gamma correction fallback for -nosrgb
X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=demo_prior;a=commitdiff_plain;h=8d209f332b7ac731aae8b7b46fc3b5622b713100

gamma correction fallback for -nosrgb
---

diff --git a/libs/glew/Makefile b/libs/glew/Makefile
index 21e9e4b..353b351 100644
--- a/libs/glew/Makefile
+++ b/libs/glew/Makefile
@@ -1,7 +1,7 @@
 obj = glew.o
 alib = libglew_static.a
 
-CFLAGS = -DGLEW_STATIC
+CFLAGS = -DGLEW_STATIC -DGLEW_INCLUDE=\"glew.h\"
 
 $(alib): $(obj)
 	$(AR) rcs $@ $(obj)
diff --git a/sdr/gamma.p.glsl b/sdr/gamma.p.glsl
new file mode 100644
index 0000000..a37f189
--- /dev/null
+++ b/sdr/gamma.p.glsl
@@ -0,0 +1,8 @@
+uniform sampler2D tex;
+
+void main()
+{
+	vec3 texel = texture2D(tex, gl_TexCoord[0].st).rgb;
+	vec3 col = pow(texel, vec3(1.0 / 2.2));
+	gl_FragColor = vec4(col, 1.0);
+}
diff --git a/sdr/gamma.v.glsl b/sdr/gamma.v.glsl
new file mode 100644
index 0000000..4c3c8ef
--- /dev/null
+++ b/sdr/gamma.v.glsl
@@ -0,0 +1,5 @@
+void main()
+{
+	gl_Position = gl_Vertex;
+	gl_TexCoord[0] = gl_MultiTexCoord0 * vec4(1.0, -1.0, 1.0, 1.0);
+}
diff --git a/src/demo.c b/src/demo.c
index d0b1127..97da536 100644
--- a/src/demo.c
+++ b/src/demo.c
@@ -2,6 +2,9 @@
 #include "opengl.h"
 #include "demo.h"
 #include "part.h"
+#include "post.h"
+#include "sdr.h"
+#include "opt.h"
 
 void reg_whitted(void);
 
@@ -9,6 +12,9 @@ int win_width, win_height;
 float win_aspect;
 long time_msec;
 
+static int reshape_pending;
+static unsigned int fbtex;
+static unsigned int sdr_gamma;
 
 int demo_init(void)
 {
@@ -23,6 +29,18 @@ int demo_init(void)
 	glEnable(GL_FRAMEBUFFER_SRGB);
 	glEnable(GL_MULTISAMPLE);
 
+	glGenTextures(1, &fbtex);
+	glBindTexture(GL_TEXTURE_2D, fbtex);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+	if(win_width) {
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, win_width, win_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+	}
+
+	if(!(sdr_gamma = create_program_load("sdr/gamma.v.glsl", "sdr/gamma.p.glsl"))) {
+		fprintf(stderr, "Warning: failed to load the gamma correction shader\n");
+	}
+
 	reg_whitted();
 
 	for(i=0; i<num_parts; i++) {
@@ -40,6 +58,13 @@ void demo_cleanup(void)
 {
 	int i;
 
+	if(sdr_gamma) {
+		glDeleteProgram(sdr_gamma);
+	}
+	if(fbtex) {
+		glDeleteTextures(1, &fbtex);
+	}
+
 	for(i=0; i<num_parts; i++) {
 		parts[i]->destroy();
 	}
@@ -49,6 +74,13 @@ void demo_display(void)
 {
 	long part_time;
 
+	if(reshape_pending) {
+		/* reshape fbtex */
+		glBindTexture(GL_TEXTURE_2D, fbtex);
+		glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, win_width, win_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+		reshape_pending = 1;
+	}
+
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 	if(!cur_part) return;
@@ -75,10 +107,21 @@ void demo_display(void)
 		prev_part = 0;
 		cur_part->draw(part_time);
 	}
+
+	/* no-srgb gamma correction fallback */
+	if(!opt.srgb) {
+		glBindTexture(GL_TEXTURE_2D, fbtex);
+		glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, win_width, win_height);
+
+		glUseProgram(sdr_gamma);
+		overlay(fbtex, win_aspect, 1.0);
+	}
 }
 
 void demo_reshape(int x, int y)
 {
+	reshape_pending = 1;
+
 	win_width = x;
 	win_height = y;
 	win_aspect = (float)x / (float)y;