spinning triangle points

cosets/src/main.cpp

@@ -1,11 +1,62 @@
-#include<glad/glad.h>
-#include<GLFW/glfw3.h>
+#include <glad/glad.h>
+#include <GLFW/glfw3.h>
 
-#include<string>
-#include<stdio.h>
+#include <string>
+#include <iostream>
+#include <cstdio>
+
+#include <glm/mat4x4.hpp>
+#include <glm/gtc/type_ptr.hpp>
+#include <glm/gtx/string_cast.hpp>
+#include <glm/gtc/matrix_transform.hpp>
 
 using namespace std;
 
+GLint build_shader(GLenum type, const string &name, const string &src) {
+   const char *c_str = src.c_str();
+
+   auto s = glCreateShader(type);
+   glShaderSource(s, 1, &c_str, nullptr);
+   glCompileShader(s);
+
+   GLint stat;
+   glGetShaderiv(s, GL_COMPILE_STATUS, &stat);
+   if (!stat) {
+      GLint log_len;
+      glGetShaderiv(s, GL_INFO_LOG_LENGTH, &log_len);
+      char log[log_len];
+      glGetShaderInfoLog(s, log_len, nullptr, log);
+      fprintf(stderr, "SHADER LOG (%s):\n%s", name.c_str(), log);
+
+      glDeleteShader(s);
+      return 0;
+   }
+
+   return s;
+}
+
+GLint build_program(const string &name, GLint vs, GLint fs) {
+   GLint p = glCreateProgram();
+   glAttachShader(p, vs);
+   glAttachShader(p, fs);
+   glLinkProgram(p);
+
+   GLint stat;
+   glGetProgramiv(p, GL_LINK_STATUS, &stat);
+   if (!stat) {
+      GLint log_len;
+      glGetShaderiv(p, GL_INFO_LOG_LENGTH, &log_len);
+      char log[log_len];
+      glGetProgramInfoLog(p, log_len, nullptr, log);
+      fprintf(stderr, "SHADER LOG (%s):\n%s", name.c_str(), log);
+
+      glDeleteProgram(p);
+      return 0;
+   }
+
+   return p;
+}
+
 class Window {
 protected:
    GLFWwindow *_window = nullptr;
@@ -62,61 +113,19 @@ public:
 
 class CosetsWindow : public Window {
    GLint program;
-   GLuint vao;
-
-   GLint build_shader(GLenum type, const string &name, const string &src) {
-      const char *c_str = src.c_str();
-
-      auto s = glCreateShader(type);
-      glShaderSource(s, 1, &c_str, nullptr);
-      glCompileShader(s);
-
-      GLint stat;
-      glGetShaderiv(s, GL_COMPILE_STATUS, &stat);
-      if (!stat) {
-         GLint log_len;
-         glGetShaderiv(s, GL_INFO_LOG_LENGTH, &log_len);
-         char log[log_len];
-         glGetShaderInfoLog(s, log_len, nullptr, log);
-         fprintf(stderr, "SHADER LOG (%s):\n%s", name.c_str(), log);
-
-         glDeleteShader(s);
-         return 0;
-      }
-
-      return s;
-   }
-
-   GLint build_program(const string &name, GLint vs, GLint fs) {
-      GLint p = glCreateProgram();
-      glAttachShader(p, vs);
-      glAttachShader(p, fs);
-      glLinkProgram(p);
-
-      GLint stat;
-      glGetProgramiv(p, GL_LINK_STATUS, &stat);
-      if (!stat) {
-         GLint log_len;
-         glGetShaderiv(p, GL_INFO_LOG_LENGTH, &log_len);
-         char log[log_len];
-         glGetProgramInfoLog(p, log_len, nullptr, log);
-         fprintf(stderr, "SHADER LOG (%s):\n%s", name.c_str(), log);
-
-         glDeleteProgram(p);
-         return 0;
-      }
-
-      return p;
-   }
+   GLuint tri;
 
 public:
    void init() override {
       auto vs = build_shader(GL_VERTEX_SHADER, "vertex",
          "#version 400\n"
+         ""
+         "uniform mat4 proj;"
+         ""
          "void main(){"
          "  float x = gl_VertexID % 2;"
          "  float y = gl_VertexID / 2;"
-         "  gl_Position = vec4(x, y, 0, 1);"
+         "  gl_Position = proj * vec4(x, y, 0, 1);"
          "}");
 
       auto fs = build_shader(GL_FRAGMENT_SHADER, "fragment",
@@ -128,24 +137,41 @@ public:
 
       program = build_program("main", vs, fs);
 
-      glGenVertexArrays(1, &vao);
+      glGenVertexArrays(1, &tri);
    }
 
    void render() override {
       int w, h;
       getBounds(w, h);
       glViewport(0, 0, w, h);
+      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+      const glm::mat4 id = glm::mat4(1);
+      const glm::vec3 ax = glm::vec3(0, 0, 1);
+      double t = glfwGetTime();
+      float angle = (float) t;
+
+      float ar = (float) w / (float) h;
+
+      const glm::mat4 proj = glm::ortho(-ar, ar, -1.f, 1.f, -1.f, 1.f);
+      const glm::mat4 view = glm::rotate(id, angle, ax);
+      const glm::mat4 mat = proj * view;
 
-      glBindVertexArray(vao);
       glUseProgram(program);
-      glDrawArrays(GL_TRIANGLES, 0, 3);
+      glUniformMatrix4fv(0, 1, false, glm::value_ptr(mat));
+      glEnable(GL_DEPTH_TEST);
+      glEnable(GL_POINT_SMOOTH);
+      glPointSize(10.f);
+
+      glBindVertexArray(tri);
+      glDrawArrays(GL_POINTS, 0, 3);
 
       swapbuffers();
    }
 
    void deinit() override {
       glDeleteProgram(program);
-      glDeleteVertexArrays(1, &vao);
+      glDeleteVertexArrays(1, &tri);
    }
 };