From ebb66ddbb17a3b82f7632a07fa4db60223b9e55a Mon Sep 17 00:00:00 2001
From: jvech <jmvalenciae@unal.edu.co>
Date: Wed, 17 Aug 2022 07:11:39 -0500
Subject: feat: Hello Triangle Done

---
 src/main.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 93 insertions(+), 12 deletions(-)

(limited to 'src/main.c')

diff --git a/src/main.c b/src/main.c
index 948932e..2d296a8 100644
--- a/src/main.c
+++ b/src/main.c
@@ -8,22 +8,38 @@
 
 #include "main.h"
 
-static void sysError(const char *msg);
+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"
+"}\0";
+
+float vertices[] = {
+    -0.5f, -0.5f, 0.0f,
+    0.5f, -0.5f, 0.0f,
+    0.0f, 0.5f, 0.0f
+};
+
+//static void sysError(const char *msg);
 static void userError(const char *msg, const char *detail);
 static void glfw_size_callback(GLFWwindow *window, int width, int height);
 static void processInput(GLFWwindow *window, struct Background *c);
-
-void
-sysError(const char *msg)
-{
-    perror(msg);
-    exit(1);
-}
+static void checkGLSuccess(unsigned int compiledShader, unsigned int shaderStep);
 
 void 
 userError(const char *msg, const char *detail)
 {
-    fprintf(stderr, "%s : %s\n", msg, detail);
+    fprintf(stderr, "%s: %s\n", msg, detail);
     exit(1);
 }
 
@@ -48,6 +64,34 @@ processInput(GLFWwindow *window, struct Background *c)
     } 
 }
 
+void 
+checkGLSuccess(unsigned int shaderBinary, unsigned int shaderStep)
+{
+    int success;
+    char infoLog[512];
+    switch (shaderStep) {
+        case 0:
+            glGetShaderiv(shaderBinary, GL_COMPILE_STATUS, &success);
+            if (!success) {
+                glGetShaderInfoLog(shaderBinary, 512, NULL, infoLog);
+                userError("glCompileShader() ERROR", infoLog);
+            }
+            break;
+
+        case 1:
+            glGetProgramiv(shaderBinary, GL_LINK_STATUS, &success);
+
+            if (!success) {
+                glGetProgramInfoLog(shaderBinary, 512, NULL, infoLog);
+                userError("glLinkProgram() ERROR", infoLog);
+            }
+            break;
+
+        default:
+            break;
+    }
+}
+
 int main()
 {
     GLFWwindow *window;
@@ -76,15 +120,52 @@ int main()
 
     struct Background colors = {.R = 0.0, .G = 0.0, .B = 0.0, .A = 0.0};
 
+    unsigned int VBO, VAO;
+    glGenVertexArrays(1, &VAO);
+    glBindVertexArray(VAO);
+
+    glGenBuffers(1, &VBO);
+    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);
+
+    unsigned int vertexShader, fragmentShader, shaderProgram;
+    vertexShader = glCreateShader(GL_VERTEX_SHADER);
+    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
+    glCompileShader(vertexShader);
+    checkGLSuccess(vertexShader, 0);
+    printf("Vertex Compiled\n");
+
+    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
+    glCompileShader(fragmentShader);
+    checkGLSuccess(fragmentShader, 0);
+    printf("Fragment Compiled\n");
+
+    shaderProgram = glCreateProgram();
+    glAttachShader(shaderProgram, vertexShader);
+    glAttachShader(shaderProgram, fragmentShader);
+    glLinkProgram(shaderProgram);
+    checkGLSuccess(shaderProgram, 1);
+
+    glDeleteShader(vertexShader);
+    glDeleteShader(fragmentShader);
+
     while (!glfwWindowShouldClose(window)) {
-        glClear(GL_COLOR_BUFFER_BIT);
+        processInput(window, &colors);
+
         glClearColor(colors.R, colors.G, colors.B, colors.A);
+        glClear(GL_COLOR_BUFFER_BIT);
+
+        glUseProgram(shaderProgram);
+        glBindVertexArray(VAO);
+        glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+        glDrawArrays(GL_TRIANGLES, 0, 3);
 
-        processInput(window, &colors);
         glfwSwapBuffers(window);
         glfwPollEvents();
     }
-
     glfwTerminate();
     return 0;
 }
-- 
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