static blue pulsating noise

fragment.glsl

@@ -2,8 +2,13 @@
 out vec4 FragColor;
 in vec2 uv;
 uniform vec2 WindowSize;
+uniform float time;
 
-void main()
-{
-    FragColor = vec4(gl_FragCoord.xy / WindowSize, 0.0, 1.0);
+float rand(vec2 co){
+    return fract(sin(dot(co, vec2(12.9898, 78.233))) * 43758.5453);
+}
+
+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);
 }

main.c

@@ -1,6 +1,7 @@
 #define GL_GLEXT_PROTOTYPES
 
 #include <stdio.h>
+#include <time.h> 
 #include <stdlib.h>
 #include <GL/gl.h>
 #include <SDL3/SDL.h>
@@ -51,7 +52,10 @@ GLuint load_shader(const char *path) {
     long length = ftell(handle);
     fseek(handle, 0L, SEEK_SET);
     char *string = malloc(length * sizeof(char));
-    fread(string, sizeof(char), length, handle);
+    if (!fread(string, sizeof(char), length, handle)) {
+        printf("failed to read shader file");
+        exit(1);
+    }
     fclose(handle);
 
     GLuint shader = create_shader(string);
@@ -60,7 +64,23 @@ GLuint load_shader(const char *path) {
     return shader;
 }
 
+struct timespec program_start;
+
+void init_timer() {
+    clock_gettime(CLOCK_MONOTONIC, &program_start);
+}
+
+double time_since_start() {
+    struct timespec now;
+    clock_gettime(CLOCK_MONOTONIC, &now);
+
+    return (now.tv_sec - program_start.tv_sec) +
+           (now.tv_nsec - program_start.tv_nsec) / 1e9;
+}
+
 int main() {
+    init_timer();
+
     printf("Good Morning 🍵\n");
     SDL_Init(SDL_INIT_VIDEO);
     SDL_Window* window = SDL_CreateWindow("SDL3 OpenGL Cube",
@@ -82,12 +102,11 @@ int main() {
 
     SDL_Event e;
     int running = 1;
-    float angle = 0.0;
 
     GLuint shader = load_shader("fragment.glsl"); //create_shader(fragment_shader_source);
-    glUseProgram(shader);
 
     int w, h;
+    double time;
     while (running) {
         while (SDL_PollEvent(&e)) {
             if (e.type == SDL_EVENT_QUIT) running = false;
@@ -100,14 +119,20 @@ int main() {
         // Rendorrrr
         glViewport(0, 0, w, h);
 
+        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);  // Dark gray background
+        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+        // Shader parameters.
+        glUseProgram(shader);
+        
         int uniform_WindowSize = glGetUniformLocation(shader, "WindowSize");
         glUniform2f(uniform_WindowSize, w, h);
 
-        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);  // Dark gray background
-        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-        
-        //drawCube();
-        // Front
+        time = time_since_start();
+        int uniform_time = glGetUniformLocation(shader, "time");
+        glUniform1f(uniform_time, (float)time);
+
+        // Draw quad.
         glBegin(GL_QUADS);
         glVertex2f(-1, 1);
         glVertex2f(-1,-1);
@@ -117,7 +142,6 @@ int main() {
         glEnd();
 
         SDL_GL_SwapWindow(window);
-        angle += 0.5;
     }
 
     checkGlError();