Copied in "Hello Triangle" code from LearnOpenGL

src/studio/src/simulator.cpp

@@ -2,6 +2,8 @@
 #include <osi/opengl.hpp>
 #include <osi/gui.hpp>
 #include <gfx/temp_file.hpp>
+#include <glad/glad.h>
+#include <iostream>
 
 namespace studio {
 
@@ -9,8 +11,93 @@ Simulator::Simulator()
     : osi::Simulator()
 {}
 
+unsigned int shaderProgram_global;
+unsigned int VAO_global;
+
+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";
+
+    
 void Simulator::update()
 {
+    unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
+    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
+    glCompileShader(vertexShader);
+
+    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;
+    }
+    shaderProgram_global = shaderProgram; //CUSTOM
+    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);
+    VAO_global = 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); 
+
+
     // Update the state (i.e., transform objects, create/destroy objects, ... )
 }
 
@@ -19,11 +106,17 @@ void Simulator::present()
     // Present the state to the user (i.e., render objects)
 
     // For now, we just clear screen buffers and show some gui widget.
-    glClearColor(0.25f, 0.25f, 0.25f, 1.0f);
+    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
     ImGui::Begin("ImGui dialog");
 	    ImGui::Text("Hello, world!");
 	ImGui::End();
+
+    glUseProgram(shaderProgram_global);
+        glBindVertexArray(VAO_global); // 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 
+
 }
 
 }