1 files changed, 41 insertions, 13 deletions
diff --git a/src/tutorial.cpp b/src/tutorial.cpp
index e3f7a9d..aa9baef 100644
--- a/src/tutorial.cpp
+++ b/src/tutorial.cpp
@@ -1,9 +1,12 @@
 // https://learnopengl.com/Getting-started/OpenGL
 
+// seriously consider GLFW et al.
+
 #include <iostream>
 
 #include <GL/glew.h>
-#include <GL/glut.h>
+//#include <GL/glut.h>
+#include <GL/freeglut.h>
 
 #include "TutorialConfig.h"
 
@@ -16,6 +19,9 @@ GLuint VAO1_glob;
 
 void renderScene(void) {
 
+        float seconds = glutGet(GLUT_ELAPSED_TIME) / 1000.0;
+        float greenValue = sin(seconds) / 2.0 + 0.5;
+
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
         glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
@@ -26,6 +32,8 @@ void renderScene(void) {
 	glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
 
         glUseProgram(shaderProgram_glob);
+        glUniform4f(glGetUniformLocation (shaderProgram_glob, "ourColor") , 0,greenValue,0,1);
+
         glBindVertexArray(VAO_glob);
         glDrawArrays(GL_TRIANGLES, 0, 3);
 
@@ -81,8 +89,9 @@ int main(int argc, char **argv) {
 
 	// init GLUT and create Window
 	glutInit(&argc, argv);
+        glutSetOption(GLUT_ALLOW_NEGATIVE_WINDOW_POSITION,true);
 	glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
-	glutInitWindowPosition(100,100);
+	glutInitWindowPosition(-500,600);
 	glutInitWindowSize(320,320);
 	glutCreateWindow("Lighthouse3D - GLUT Tutorial");
 	glutIdleFunc(idle);
@@ -122,20 +131,39 @@ int main(int argc, char **argv) {
               exit(1); // or handle the error in a nicer way
         }
 
+        int nrAttributes;
+        glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &nrAttributes);
+        std::cout << "Maximum nr of vertex attributes supported: " << nrAttributes << std::endl;
+
         int  success;
         char infoLog[512];
 
-        const char *vertexShaderSource = "#version 330 core\n"
-                "layout (location = 0) in vec3 aPos;\n"
-                    "void main()\n"
-                        "{\n"
-                            "   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
-                                "}\0";
-        const char *fragmentShaderSource = "#version 330 core\n"
-            "out vec4 FragColor;  void main()   {           FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);      } \0";
-
-        const char *fragmentShader1Source = "#version 330 core\n"
-            "out vec4 FragColor;  void main()   {           FragColor = vec4(1.0f, 0.0f, 0.0f, 1.0f);      } \0";
+        const char *vertexShaderSource = 
+            "#version 330 core\n"
+            "layout (location = 0) in vec3 aPos;\n"
+            "out vec4 vertexColor;\n"
+            "uniform vec4 ourColor;"
+            "void main(){"
+            "gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);"
+            "vertexColor = vec4(aPos.y,aPos.x,ourColor.y,1.0);"
+            "vertexColor = ourColor;"
+            "}\0";
+
+        const char *fragmentShaderSource =
+            "#version 330 core\n"
+            "out vec4 FragColor;"
+            "in vec4 vertexColor;"
+            "void main(){"
+            "FragColor = vertexColor;"
+            "}\0";
+
+        const char *fragmentShader1Source =
+            "#version 330 core\n"
+            "out vec4 FragColor;"
+            "in vec4 vertexColor;"
+            "void main(){"
+            "FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);"
+            "}\0";
 
         GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
         glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);