diff --git a/Makefile b/Makefile
index 5c94d91..5f778f1 100644
--- a/Makefile
+++ b/Makefile
@@ -87,6 +87,7 @@ clean:
 MAIN_OBJS = \
 	src/main.o \
 	src/glad.o \
+	src/opengl.o \
 	$(patsubst %.glsl,%.glsl.o,$(wildcard src/shader/*.glsl)) \
 	$(GLFW)
 
diff --git a/src/main.c b/src/main.c
index d6999c4..fdf432d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,9 +7,13 @@
 #include "shader/vertex_color.fp.glsl.h"
 #include "shader/vertex_color.vp.glsl.h"
 
+#include "opengl.h"
+
 static int vp_width = 800;
 static int vp_height = 600;
 
+typedef unsigned int uint;
+
 void framebuffer_size_callback(GLFWwindow* window, int width, int height)
 {
   glViewport(0, 0, width, height);
@@ -59,16 +63,17 @@ int main()
   // buffer initialization
   //////////////////////////////////////////////////////////////////////
 
-  /*
-  unsigned int triangle_vertex_buffer = make_buffer(GL_ARRAY_BUFFER,
-                                                    triangle_vertex_buffer_data,
-                                                    (sizeof (triangle_vertex_buffer_data)));
-  */
+  uint triangle_vertex_buffer = make_buffer(GL_ARRAY_BUFFER,
+                                            triangle_vertex_buffer_data,
+                                            (sizeof (triangle_vertex_buffer_data)));
 
-  /*
-  vertex_color.program = compile_shaders("src/vertex_color.vp.glsl",
-                                         "src/vertex_color_fp_render.fp.glsl");
-  */
+  uint vertex_color_program = compile_shader(src_shader_vertex_color_vp_glsl_start,
+                                             src_shader_vertex_color_vp_glsl_size,
+                                             src_shader_vertex_color_fp_glsl_start,
+                                             src_shader_vertex_color_fp_glsl_size);
+  glUseProgram(vertex_color_program);
+  uint vertex_color_attrib_position = glGetAttribLocation(vertex_color_program, "position");
+  uint vertex_color_attrib_color = glGetAttribLocation(vertex_color_program, "color");
 
   //////////////////////////////////////////////////////////////////////
   // main loop
@@ -82,6 +87,29 @@ int main()
   while(!glfwWindowShouldClose(window)) {
     if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
       glfwSetWindowShouldClose(window, true);
+
+    glBindBuffer(GL_ARRAY_BUFFER, triangle_vertex_buffer);
+    glVertexAttribPointer(vertex_color_attrib_position,
+                          3,
+                          GL_FLOAT,
+                          GL_FALSE,
+                          (sizeof (float)) * 6,
+                          (void*)0
+                          );
+    glVertexAttribPointer(vertex_color_attrib_color,
+                          3,
+                          GL_FLOAT,
+                          GL_FALSE,
+                          (sizeof (float)) * 6,
+                          (void*)(3 * 4)
+                          );
+    glEnableVertexAttribArray(vertex_color_attrib_position);
+    glEnableVertexAttribArray(vertex_color_attrib_color);
+
+    glDrawArrays(GL_TRIANGLES, 0, 3);
+
+    glfwSwapBuffers(window);
+    glfwPollEvents();
   }
 
   glfwTerminate();
diff --git a/src/opengl.c b/src/opengl.c
index 5d71057..b41cd3d 100644
--- a/src/opengl.c
+++ b/src/opengl.c
@@ -1,58 +1,62 @@
-unsigned int compile_shader(const char * vp_path, const char * fp_path)
+#include <stddef.h>
+#include <stdio.h>
+
+#include "glad/glad.h"
+
+unsigned int compile_shader(const void * vp,
+                            const int vp_length,
+                            const void * fp,
+                            const int fp_length)
 {
-  void * vertexShaderSource = read_file(vp_path);
-  unsigned int vertexShader;
-  vertexShader = glCreateShader(GL_VERTEX_SHADER);
-  glShaderSource(vertexShader, 1, (const char **)&vertexShaderSource, NULL);
-  glCompileShader(vertexShader);
+  unsigned int vertex_shader;
+  vertex_shader = glCreateShader(GL_VERTEX_SHADER);
+  glShaderSource(vertex_shader, 1, (const char **)&vp, &vp_length);
+  glCompileShader(vertex_shader);
   {
     int  success;
-    char infoLog[512];
-    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
+    char info_log[512];
+    glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
     if(!success) {
-      glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
-      printf("vertex shader compile failed:\n%s\n", infoLog);
-    }
-  }
-  free(vertexShaderSource);
-
-  void * fragmentShaderSource = read_file(fp_path);
-  unsigned int fragmentShader;
-  fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
-  glShaderSource(fragmentShader, 1, (const char **)&fragmentShaderSource, NULL);
-  glCompileShader(fragmentShader);
-  {
-    int  success;
-    char infoLog[512];
-    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
-    if(!success) {
-      glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
-      printf("fragment shader compile failed:\n%s\n", infoLog);
-    }
-  }
-  free(fragmentShaderSource);
-
-  unsigned int shaderProgram;
-  shaderProgram = glCreateProgram();
-
-  glAttachShader(shaderProgram, vertexShader);
-  glAttachShader(shaderProgram, fragmentShader);
-  glLinkProgram(shaderProgram);
-
-  {
-    int  success;
-    char infoLog[512];
-    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
-    if(!success) {
-      glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
-      printf("program link failed:\n%s\n", infoLog);
+      glGetShaderInfoLog(vertex_shader, 512, NULL, info_log);
+      fprintf(stderr, "vertex shader compile failed:\n%s\n", info_log);
     }
   }
 
-  glDeleteShader(vertexShader);
-  glDeleteShader(fragmentShader);
+  unsigned int fragment_shader;
+  fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
+  glShaderSource(fragment_shader, 1, (const char **)&fp, &fp_length);
+  glCompileShader(fragment_shader);
+  {
+    int  success;
+    char info_log[512];
+    glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);
+    if(!success) {
+      glGetShaderInfoLog(fragment_shader, 512, NULL, info_log);
+      fprintf(stderr, "fragment shader compile failed:\n%s\n", info_log);
+    }
+  }
 
-  return shaderProgram;
+  unsigned int shader_program;
+  shader_program = glCreateProgram();
+
+  glAttachShader(shader_program, vertex_shader);
+  glAttachShader(shader_program, fragment_shader);
+  glLinkProgram(shader_program);
+
+  {
+    int  success;
+    char info_log[512];
+    glGetProgramiv(shader_program, GL_LINK_STATUS, &success);
+    if(!success) {
+      glGetProgramInfoLog(shader_program, 512, NULL, info_log);
+      fprintf(stderr, "program link failed:\n%s\n", info_log);
+    }
+  }
+
+  glDeleteShader(vertex_shader);
+  glDeleteShader(fragment_shader);
+
+  return shader_program;
 }
 
 int make_buffer(unsigned int target,
diff --git a/src/opengl.h b/src/opengl.h
new file mode 100644
index 0000000..3bbaed1
--- /dev/null
+++ b/src/opengl.h
@@ -0,0 +1,8 @@
+unsigned int compile_shader(const void * vp,
+                            const size_t vp_length,
+                            const void * fp,
+                            const size_t fp_length);
+
+int make_buffer(unsigned int target,
+                const void * data,
+                size_t size);