initial commit

3 files changed, 280 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5e55c3f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.o
+compute-test
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..cb1ae8e
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,17 @@
+CFLAGS=-std=c11 -W -Wall -pedantic -O2
+APP=compute-test
+LIBS=-lglfw -lGLEW -lGL
+OBJS=main.o
+
+.PHONY=all clean test
+
+all: $(APP)
+
+$(APP): $(OBJS)
+	$(CC) -o $(APP) $(OBJS) $(LIBS)
+
+clean:
+	$(RM) $(OBJS) $(APP)
+
+test: $(APP)
+	./$(APP)
diff --git a/main.c b/main.c
new file mode 100644
index 0000000..22266db
--- /dev/null
+++ b/main.c
@@ -0,0 +1,261 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <GL/glew.h>
+#include <GLFW/glfw3.h>
+
+#define UNUSED(a) ((void) (a))
+
+static const float
+verts[] = {
+  -0.5,  0.5, 0,
+   0.5,  0.5, 0,
+   0.0, -0.5, 0,
+};
+
+static const char *
+vs_src = 
+  "#version 320 es\n"
+  "\n"
+  "layout (location = 0) in mediump vec3 pos;\n"
+  "\n"
+  "void main() {\n"
+  "  gl_Position = vec4(pos.x, pos.y, pos.z, 1);\n"
+  "}\n";
+
+static const char *
+fs_src = 
+  "#version 320 es\n"
+  "\n"
+  "out mediump vec4 color;\n"
+  "\n"
+  "uniform mediump float time;\n"
+  "\n"
+  "void main() {\n"
+  "  color = vec4(0.5f + 0.5 * sin(time * 3.141), 0, 0, 1);\n"
+  "}\n";
+
+static void
+error_cb(
+  const int code,
+  const char *text
+) {
+  UNUSED(code);
+  fprintf(stderr, "GLFW Error: %s\n", text);
+}
+
+static void
+key_cb(
+  GLFWwindow *win,
+  int key,
+  int code,
+  int action,
+  int mods
+) {
+  UNUSED(code);
+  UNUSED(mods);
+
+  if (action == GLFW_RELEASE && key == GLFW_KEY_ESCAPE)
+    glfwSetWindowShouldClose(win, GLFW_TRUE);
+}
+
+static void
+framebuffer_size_cb(
+  GLFWwindow *win,
+  const int width,
+  const int height
+) {
+  UNUSED(win);
+
+  fprintf(stderr, "width = %d, height = %d\n", width, height);
+  glViewport(0, 0, width, height);
+}
+
+static void drop_cb(
+  GLFWwindow *win,
+  const int num_paths,
+  const char ** paths
+) {
+  UNUSED(win);
+
+  for (int i = 0; i < num_paths; i++) {
+    fprintf(stderr, "drop path: %s\n", paths[i]);
+  }
+}
+
+static GLuint
+compile_shader(
+  const GLenum type,
+  const char *src
+) {
+  // create shader
+  GLuint r = glCreateShader(type);
+
+  // compile shader
+  glShaderSource(r, 1, &src, NULL);
+  glCompileShader(r);
+
+  // check for error
+  GLint ok;
+  glGetShaderiv(r, GL_COMPILE_STATUS, &ok);
+  if (!ok) {
+    GLchar log[1024];
+    glGetShaderInfoLog(r, sizeof(log), NULL, log);
+    fprintf(stderr, "Shader Compile Error: %s\n", log);
+    exit(EXIT_FAILURE);
+  }
+
+  // return result
+  return r;
+}
+
+static GLuint
+link_render_program(
+  const char * const vs_src,
+  const char * const fs_src
+) {
+  // create program
+  GLuint r = glCreateProgram();
+
+  // compile shaders
+  GLuint vs = compile_shader(GL_VERTEX_SHADER, vs_src),
+         fs = compile_shader(GL_FRAGMENT_SHADER, fs_src);
+
+  // attach shaders
+  glAttachShader(r, vs);
+  glAttachShader(r, fs);
+
+  // link program
+  glLinkProgram(r);
+
+  // check link status
+  GLint ok;
+  glGetProgramiv(r, GL_LINK_STATUS, &ok);
+  if (!ok) {
+    GLchar log[1024];
+    glGetProgramInfoLog(r, sizeof(log), NULL, log);
+    fprintf(stderr, "Program Link Error: %s\n", log);
+    exit(EXIT_FAILURE);
+  }
+
+  // delete shaders 
+  glDeleteShader(vs);
+  glDeleteShader(fs);
+
+  // return result
+  return r;
+}
+
+#if 0
+static GLuint
+link_compute_program(
+  const char * const cs_src
+) {
+  // create program
+  GLuint r = glCreateProgram();
+
+}
+#endif
+
+static GLFWwindow *
+init(void) {
+  // init glfw
+  glfwSetErrorCallback(error_cb);
+  if (!glfwInit())
+    exit(EXIT_FAILURE);
+
+  // set api to GLES 3.2
+  glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);
+  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
+
+  // create window
+  GLFWwindow *win = glfwCreateWindow(640, 480, "Compute Test", NULL, NULL);
+  if (!win) {
+    exit(EXIT_FAILURE);
+  }
+
+  // set gl context
+  glfwMakeContextCurrent(win);
+
+  // init glew
+  // (do this immediately after setting context)
+  GLenum err = glewInit();
+  if (err != GLEW_OK) {
+    fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
+    exit(EXIT_FAILURE);
+  }
+
+  // set swap interval
+  // (after context init)
+  glfwSwapInterval(1);
+
+  // bind event handlers
+  // (after context init)
+  glfwSetKeyCallback(win, key_cb);
+  glfwSetFramebufferSizeCallback(win, framebuffer_size_cb);
+  glfwSetDropCallback(win, drop_cb);
+
+  // return window
+  return win;
+}
+
+int main(int argc, char *argv[]) {
+  UNUSED(argc);
+  UNUSED(argv);
+
+  GLFWwindow *win = init();
+
+  // generate vertex array
+  GLuint vao;
+  glGenVertexArrays(1, &vao);
+  glBindVertexArray(vao);
+
+  // generate vertex buffer
+  GLuint vbo;
+  glGenBuffers(1, &vbo);
+  glBindBuffer(GL_ARRAY_BUFFER, vbo);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(verts), verts, GL_STATIC_DRAW);
+
+  glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*) 0);
+  glEnableVertexAttribArray(0);
+
+  // unbind vao
+  glBindVertexArray(0);
+
+  // link program
+  GLuint prog = link_render_program(vs_src, fs_src);
+  GLint u_time = glGetUniformLocation(prog, "time");
+
+  // main loop
+  while (!glfwWindowShouldClose(win)) {
+    // clear screen
+    glClearColor(0, 0, 0, 1);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    // use program, set uniform
+    glUseProgram(prog);
+    glUniform1f(u_time, glfwGetTime());
+
+    // draw
+    glBindVertexArray(vao);
+    glDrawArrays(GL_TRIANGLES, 0, 3);
+    glBindVertexArray(0);
+
+    // swap buffer
+    glfwSwapBuffers(win);
+
+    // handle events
+    glfwPollEvents();
+    // glfwWaitEvents();
+  }
+
+  // destroy window
+  glfwDestroyWindow(win);
+
+  // fini glfw
+  glfwTerminate();
+
+  // return success
+  return EXIT_SUCCESS;
+}