p

fragment.glsl

@@ -1,6 +1,5 @@
 #version 330 core
 out vec4 FragColor;
-in vec2 uv;
 uniform vec2 WindowSize;
 uniform float time;
 
@@ -8,7 +7,28 @@ float rand(vec2 co){
     return fract(sin(dot(co, vec2(12.9898, 78.233))) * 43758.5453);
 }
 
+float cell_size = 0.1;
+
 void main() {
-    float glob = rand(gl_FragCoord.xy / WindowSize + time);
-    FragColor = vec4(glob * (sin(time)/2 + 0.5), glob, 1.0, 1.0); //vec4(gl_FragCoord.xy / WindowSize, 0.0, 1.0);
+    // We'll make origin in the top-left.
+    vec2 uv = gl_FragCoord.xy / WindowSize;
+    uv.y = 1.0 - uv.y;
+    vec2 grid_edge_offset = mod(uv, cell_size);
+    // c: corner
+    vec2 c_tl = uv - grid_edge_offset;
+    vec2 c_tr = uv - grid_edge_offset + vec2(cell_size, 0);
+    vec2 c_bl = uv - grid_edge_offset + vec2(0,         cell_size);
+    vec2 c_br = uv - grid_edge_offset + vec2(cell_size, cell_size);
+    // random vectors
+    vec2 c_tl_ran = rand(c_tl);
+    vec2 c_tr_ran = rand(c_tr);
+    vec2 c_bl_ran = rand(c_bl);
+    vec2 c_br_ran = rand(c_br);
+    // offset vectors
+    vec2 c_tl_off = c_tl - uv;
+    vec2 c_tr_off = c_tr - uv;
+    vec2 c_bl_off = c_bl - uv;
+    vec2 c_br_off = c_br - uv;
+
+    FragColor = 
 }

main.c

@@ -13,8 +13,9 @@ void checkGlError() {
     }
 }
 
+/// returns 0 if failed.
 GLuint compile_shader(GLuint type, const char *src) {
-    GLuint id = glCreateShader(GL_FRAGMENT_SHADER);
+    GLuint id = glCreateShader(type);
     glShaderSource(id, 1, &src, 0);
     glCompileShader(id);
 
@@ -34,16 +35,19 @@ GLuint compile_shader(GLuint type, const char *src) {
     return id;
 }
 
+/// returns 0 if failed.
 GLuint create_shader(const char *fragment_src) {
     GLuint program = glCreateProgram();
     GLuint fragment_shader = compile_shader(GL_FRAGMENT_SHADER, fragment_src);
-
-    glAttachShader(program, fragment_shader);
-    glLinkProgram(program);
-    glValidateProgram(program);
-    glDeleteShader(fragment_shader);
-
-    return program;
+    if (!(fragment_shader == 0)) {
+        glAttachShader(program, fragment_shader);
+        glLinkProgram(program);
+        glValidateProgram(program);
+        glDeleteShader(fragment_shader);
+        return program;
+    } else {
+        return 0;
+    }
 }
 
 GLuint load_shader(const char *path) {
@@ -60,6 +64,21 @@ GLuint load_shader(const char *path) {
 
     GLuint shader = create_shader(string);
 
+    if (shader == 0) {
+        // print file
+        int line_count = 1;
+        printf("%i\t", line_count);
+        line_count++;
+        for (int i = 0; i < length; i++) {
+            printf("%c", string[i]);
+            if (string[i] == '\n') {
+                printf("%i\t", line_count);
+                line_count++;
+            }
+        }
+        printf("\n");
+    }
+
     free(string);
     return shader;
 }

pulsating-noise.glsl

@@ -0,0 +1,17 @@
+#version 330 core
+out vec4 FragColor;
+uniform vec2 WindowSize;
+uniform float time;
+
+float rand(vec2 co){
+    return fract(sin(dot(co, vec2(12.9898, 78.233))) * 43758.5453);
+}
+
+float cell_size = 0.1;
+
+void main() {
+    vec2 uv = gl_FragCoord.xy / WindowSize;
+    // grid
+    float glob = rand(uv + time);
+    FragColor = vec4(glob * (sin(time)/2 + 0.5), glob, 1.0, 1.0); //vec4(gl_FragCoord.xy / WindowSize, 0.0, 1.0);
+}