From ee0c5a43c122991f1ae51a4c0870d1d6675f3533 Mon Sep 17 00:00:00 2001
From: kdx <kikoodx@paranoici.org>
Date: Mon, 22 May 2023 00:43:59 +0200
Subject: random dithering

---
 src/fragment.glsl | 21 ++++++++++++---------
 src/main.c        |  3 ++-
 src/vertex.glsl   |  3 +++
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/src/fragment.glsl b/src/fragment.glsl
index edeccab..e233466 100644
--- a/src/fragment.glsl
+++ b/src/fragment.glsl
@@ -2,23 +2,26 @@
 out vec4 FragColor;
 
 in vec2 texCoord;
+in float randOffset;
 
 uniform sampler2D texture0;
 uniform sampler2D texture1;
 
+/* thank you internet i guess 
+ * note: this has terrible distribution, not sure if i care */
+float
+rand(vec2 co){
+	return fract(sin(dot(co.xy ,vec2(12.9898,78.233))+randOffset) * 43758.5453);
+}
+
 void
 main()
 {
 	vec4 col = mix(texture(texture0, texCoord),
 	               texture(texture1, texCoord), 0.2);
-	col.r = (col.r < 0.5) ? 0.0 : 1.0;
-	col.g = (col.g < 0.5) ? 0.0 : 1.0;
-	col.b = (col.b < 0.5) ? 0.0 : 1.0;
-	if (col.r == 1.0 && col.g == 1.0)
-		col.rgb = vec3(1.0, 1.0, 0.0);
-	else if (col.r == 1.0)
-		col.rgb = vec3(0.0, 1.0, 1.0);
+	float gray = 0.2989 * col.r + 0.5870 * col.g + 0.1140 * col.b;
+	if (gray + rand(texCoord) - 0.5 < 0.5)
+		FragColor = vec4(vec3(0.0), 1.0);
 	else
-		col.rgb = vec3(1.0, 0.0, 1.0);
-	FragColor = col;
+		FragColor = vec4(1.0);
 }
diff --git a/src/main.c b/src/main.c
index e8f14d7..69a2d8e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -136,12 +136,13 @@ main([[maybe_unused]] int argc, [[maybe_unused]] char **argv)
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, GL_LINEAR);
 
 	while (!glfwWindowShouldClose(window)) {
-		glClearColor(1.0f, 0.0f, 1.0f, 1.0f);
+		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
 		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 		shader_use(&shader);
 		glUniform1i(shader_uniform_location(&shader, "texture0"), 0);
 		glUniform1i(shader_uniform_location(&shader, "texture1"), 1);
+		glUniform1f(shader_uniform_location(&shader, "randOffset"), rand() / (float)rand());
 		glActiveTexture(GL_TEXTURE0);
 		glBindTexture(GL_TEXTURE_2D, texture.id);
 		glActiveTexture(GL_TEXTURE1);
diff --git a/src/vertex.glsl b/src/vertex.glsl
index 0a6f24e..9083749 100644
--- a/src/vertex.glsl
+++ b/src/vertex.glsl
@@ -1,8 +1,10 @@
 #version 330 core
 layout (location = 0) in vec3 aPos;
 layout (location = 1) in vec2 aTexCoord;
+layout (location = 2) in float randOffset;
 
 out vec2 texCoord;
+out float fragRandOffset;
 
 uniform mat4 model;
 uniform mat4 view;
@@ -14,4 +16,5 @@ main()
 {
 	gl_Position = projection * view * model * transform * vec4(aPos, 1.0);
 	texCoord = aTexCoord;
+	fragRandOffset = randOffset;
 }
-- 
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