feat: rewrite to cpp + refactor into files

src/shader.cpp

@@ -0,0 +1,45 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "shader.h"
+
+GLuint compile_shader(GLenum type, const char *src) {
+    GLuint shader = glCreateShader(type);
+    glShaderSource(shader, 1, &src, NULL);
+    glCompileShader(shader);
+
+    GLint ok;
+    glGetShaderiv(shader, GL_COMPILE_STATUS, &ok);
+    if (!ok) {
+        char log[512];
+        glGetShaderInfoLog(shader, sizeof(log), NULL, log);
+        fprintf(stderr, "shader compile error: %s\n", log);
+        exit(1);
+    }
+
+    return shader;
+}
+
+GLuint create_program(const char *vs_src, const char *fs_src) {
+    GLuint vs = compile_shader(GL_VERTEX_SHADER, vs_src);
+    GLuint fs = compile_shader(GL_FRAGMENT_SHADER, fs_src);
+
+    GLuint prog = glCreateProgram();
+    glAttachShader(prog, vs);
+    glAttachShader(prog, fs);
+    glLinkProgram(prog);
+
+    GLint ok;
+    glGetProgramiv(prog, GL_LINK_STATUS, &ok);
+    if (!ok) {
+        char log[512];
+        glGetProgramInfoLog(prog, sizeof(log), NULL, log);
+        fprintf(stderr, "program link error: %s\n", log);
+        exit(1);
+    }
+
+    glDeleteShader(vs);
+    glDeleteShader(fs);
+
+    return prog;
+}