From 45453d8ebc2f7960cf2e9228a1378c63fe572daf Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Tue, 13 Oct 2015 23:03:45 -0400
Subject: [PATCH] draw a cube; rotate cube over time; enable cull face

---
 app.cc | 39 +++++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/app.cc b/app.cc
index c9d730c..d35ca00 100644
--- a/app.cc
+++ b/app.cc
@@ -32,6 +32,7 @@ bool init(void)
 {
     glClearColor (0.0, 0.0, 0.0, 0.0);
     glEnable(GL_DEPTH_TEST);
+    glEnable(GL_CULL_FACE);
 #if 0
     glEnable(GL_BLEND);
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
@@ -107,6 +108,19 @@ bool init(void)
 
 static void draw_cube()
 {
+    static const struct
+    {
+        int counts;
+        float axis[3];
+    } rotations[] = {
+        {0, {0, 0, 0}},
+        {1, {1, 0, 0}},
+        {2, {1, 0, 0}},
+        {3, {1, 0, 0}},
+        {1, {0, 1, 0}},
+        {3, {0, 1, 0}},
+    };
+
     glm::mat4 modelview_backup = modelview;
 
     program->use();
@@ -116,16 +130,33 @@ static void draw_cube()
     glUniform4f(uniforms.specular, 1.0, 1.0, 1.0, 1.0);
     glUniform1f(uniforms.shininess, 150.0);
     glUniform1i(uniforms.tex, 0);
-    glUniformMatrix4fv(uniforms.modelview, 1, GL_FALSE, &modelview[0][0]);
     glUniformMatrix4fv(uniforms.projection, 1, GL_FALSE, &projection[0][0]);
-    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+
+    for (int i = 0; i < sizeof(rotations) / sizeof(rotations[0]); i++)
+    {
+        if (rotations[i].counts > 0)
+        {
+            modelview = glm::rotate(modelview_backup,
+                                    (float)(M_PI / 2.0 * rotations[i].counts),
+                                    glm::vec3(rotations[i].axis[0],
+                                              rotations[i].axis[1],
+                                              rotations[i].axis[2]));
+        }
+        glUniformMatrix4fv(uniforms.modelview, 1, GL_FALSE, &modelview[0][0]);
+        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+    }
+
+    modelview = modelview_backup;
 }
 
 void display(SDL_Window * window)
 {
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
-    modelview = glm::translate(glm::mat4(1.0), glm::vec3(0, 0, -5));
-    modelview = glm::rotate(modelview, (float)(SDL_GetTicks() / 1000.0), glm::vec3(0, 1, 0));
+    modelview = glm::lookAt(glm::vec3(-1, -8, 7),
+                            glm::vec3(0, 0, 0),
+                            glm::vec3(0, 0, 1));
+    modelview = glm::rotate(modelview, (float)(SDL_GetTicks() / 1000.0), glm::vec3(0, 0, 1));
+    modelview = glm::translate(modelview, glm::vec3(3, 0, 0));
 
     draw_cube();