example 2HEADmaster

1 files changed, 100 insertions, 2 deletions

diff --git a/example.cpp b/example.cpp
index 97cf5b2..8535a58 100644
--- a/example.cpp
+++ b/example.cpp
@@ -1,3 +1,4 @@
+// loosely following along learnopengl.com
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
 
@@ -10,6 +11,19 @@ void processInput(GLFWwindow *window);
 const unsigned int SCR_WIDTH = 800;
 const unsigned int SCR_HEIGHT = 600;
 
+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;\n"
+    "void main()\n"
+    "{\n"
+    "   FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
+    "}\n\0";
+
 int main()
 {
     // glfw: initialize and configure
@@ -41,7 +55,79 @@ int main()
     {
         std::cout << "Failed to initialize GLAD" << std::endl;
         return -1;
-    }    
+    }
+
+
+    // build and compile our shader program
+    // ------------------------------------
+    // vertex shader
+    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
+    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
+    glCompileShader(vertexShader);
+    // check for shader compile errors
+    int success;
+    char infoLog[512];
+    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
+    if (!success)
+    {
+        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
+        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
+    }
+    // fragment shader
+    unsigned int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
+    glCompileShader(fragmentShader);
+    // check for shader compile errors
+    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
+    if (!success)
+    {
+        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
+        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
+    }
+    // link shaders
+    unsigned int shaderProgram = glCreateProgram();
+    glAttachShader(shaderProgram, vertexShader);
+    glAttachShader(shaderProgram, fragmentShader);
+    glLinkProgram(shaderProgram);
+    // check for linking errors
+    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
+    if (!success) {
+        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
+        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
+    }
+    glDeleteShader(vertexShader);
+    glDeleteShader(fragmentShader);
+
+    // set up vertex data (and buffer(s)) and configure vertex attributes
+    // ------------------------------------------------------------------
+    float vertices[] = {
+        -0.5f, -0.5f, 0.0f, // left  
+         0.5f, -0.5f, 0.0f, // right 
+         0.0f,  0.5f, 0.0f  // top   
+    }; 
+
+    unsigned int VBO, VAO;
+    glGenVertexArrays(1, &VAO);
+    glGenBuffers(1, &VBO);
+    // bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s).
+    glBindVertexArray(VAO);
+
+    glBindBuffer(GL_ARRAY_BUFFER, VBO);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+    glEnableVertexAttribArray(0);
+
+    // note that this is allowed, the call to glVertexAttribPointer registered VBO as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind
+    glBindBuffer(GL_ARRAY_BUFFER, 0); 
+
+    // You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other
+    // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary.
+    glBindVertexArray(0); 
+
+
+    // uncomment this call to draw in wireframe polygons.
+    //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 
     // render loop
     // -----------
@@ -56,12 +142,24 @@ int main()
         glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT);
 
+        // draw our first triangle
+        glUseProgram(shaderProgram);
+        glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized
+        glDrawArrays(GL_TRIANGLES, 0, 3);
+        // glBindVertexArray(0); // no need to unbind it every time 
+ 
         // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
         // -------------------------------------------------------------------------------
         glfwSwapBuffers(window);
         glfwPollEvents();
     }
 
+    // optional: de-allocate all resources once they've outlived their purpose:
+    // ------------------------------------------------------------------------
+    glDeleteVertexArrays(1, &VAO);
+    glDeleteBuffers(1, &VBO);
+    glDeleteProgram(shaderProgram);
+
     // glfw: terminate, clearing all previously allocated GLFW resources.
     // ------------------------------------------------------------------
     glfwTerminate();
@@ -72,7 +170,7 @@ int main()
 // ---------------------------------------------------------------------------------------------------------
 void processInput(GLFWwindow *window)
 {
-    if(glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
+    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
         glfwSetWindowShouldClose(window, true);
 }