From bf93695d54c19b4e7b9189874166d56379d401eb Mon Sep 17 00:00:00 2001
From: Luca Giuliano Conte <main@lugico.de>
Date: Thu, 14 Mar 2024 11:34:13 +0100
Subject: [PATCH] u01 triangle

---
 u01/Makefile |   5 +-
 u01/main.c   | 167 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 170 insertions(+), 2 deletions(-)

diff --git a/u01/Makefile b/u01/Makefile
index d91c4a1..8e1eafb 100644
--- a/u01/Makefile
+++ b/u01/Makefile
@@ -1,2 +1,5 @@
+GLEW_LIBS=$(shell pkgconf glew --libs)
+GLFW_LIBS=$(shell pkgconf glfw3 --libs)
+
 cg1: main.c
-	gcc -o cg1.exe main.c
\ No newline at end of file
+	gcc -o cg1.out main.c $(GLEW_LIBS) $(GLFW_LIBS)
\ No newline at end of file
diff --git a/u01/main.c b/u01/main.c
index 4511edc..3a42211 100644
--- a/u01/main.c
+++ b/u01/main.c
@@ -1,6 +1,171 @@
 #include <stdio.h>
 
+#include <GL/glew.h>
+#include <GLFW/glfw3.h>
+
+GLuint program;
+GLuint vao;
+
+void init(void) {
+	// create and compile vertex shader
+	const char *vertexText = 
+		"#version 330 core\n"
+		"layout (location = 0) in vec2 aPosition;\n"
+		"layout (location = 1) in vec3 aColor;\n"
+		"out vec3 vertexColor;\n"
+		"void main() {\n"
+		"  vertexColor = aColor;\n"
+		"  gl_Position = vec4(aPosition, 0.0, 1.0);\n"
+		"}\n";
+	GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
+	glShaderSource(vertexShader, 1, &vertexText, NULL);
+	glCompileShader(vertexShader);
+
+	GLint status;
+	glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &status);
+	
+	if (!status) {
+		printf("Error compiling vertex shader: ");
+		GLchar infoLog[1024];
+		glGetShaderInfoLog(vertexShader, 1024, NULL, infoLog);
+		printf("%s",infoLog);
+	}
+
+	// create and compile fragment shader
+	const char *fragmentText = 
+		"#version 330 core\n"
+		"in vec3 vertexColor;\n"
+		"void main() {\n"
+		"  gl_FragColor = vec4(vertexColor, 1.0);\n"
+		"}\n";
+	GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+	glShaderSource(fragmentShader, 1, &fragmentText, NULL);
+	glCompileShader(fragmentShader);
+
+	glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &status);
+	
+	if (!status) {
+		printf("Error compiling fragment shader: ");
+		GLchar infoLog[1024];
+		glGetShaderInfoLog(fragmentShader, 1024, NULL, infoLog);
+		printf("%s",infoLog);
+	}
+
+	// create and link shader program
+	program = glCreateProgram();
+	glAttachShader(program, vertexShader);
+	glAttachShader(program, fragmentShader);
+	glLinkProgram(program);
+
+	glGetProgramiv(program, GL_LINK_STATUS, &status);
+
+	if (!status) {
+		printf("Error linking program: ");
+		GLchar infoLog[1024];
+		glGetProgramInfoLog(program, 1024, NULL, infoLog);
+		printf("%s",infoLog);
+	}
+	glValidateProgram(program);
+
+
+	glGetProgramiv(program, GL_VALIDATE_STATUS, &status);
+
+	if (!status) {
+		printf("Error validating program: ");
+		GLchar infoLog[1024];
+		glGetProgramInfoLog(program, 1024, NULL, infoLog);
+		printf("%s",infoLog);
+	}
+
+
+	// create triangle buffer
+	GLfloat triangleVertices[] =
+		{//   X    Y
+			 0.0f, 0.5f, 1.0f, 0.0f, 0.0f,
+			-0.5f, -0.5f, 0.0f, 1.0f, 0.0f,
+			 0.5f, -0.5f, 0.0f, 0.0f, 1.0f
+		};
+	GLuint triangleVertexBufferObject;
+	glGenBuffers(1, &triangleVertexBufferObject);
+	glBindBuffer(GL_ARRAY_BUFFER, triangleVertexBufferObject);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(triangleVertices), triangleVertices, GL_STATIC_DRAW);
+	glBindBuffer(GL_ARRAY_BUFFER, 0);
+
+
+	// create vertex array object
+	glGenVertexArrays(1, &vao);
+	glBindVertexArray(vao);
+	glBindBuffer(GL_ARRAY_BUFFER, triangleVertexBufferObject);
+	glVertexAttribPointer(
+		0,
+		2,
+		GL_FLOAT,
+		GL_FALSE,
+		5 * sizeof(GLfloat),
+		0
+	);
+	glEnableVertexAttribArray(0);
+	glVertexAttribPointer(
+		1,
+		3,
+		GL_FLOAT,
+		GL_FALSE,
+		5 * sizeof(GLfloat),
+		(GLvoid*)(2 * sizeof(GLfloat))
+	);
+	glEnableVertexAttribArray(1);
+	glBindBuffer(GL_ARRAY_BUFFER, 0);
+	glBindVertexArray(0);
+
+
+
+	glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
+}
+
+void draw(void) {
+	glClear(GL_COLOR_BUFFER_BIT);
+	glUseProgram(program);
+	glBindVertexArray(vao);
+
+	glDrawArrays(GL_TRIANGLES, 0, 3);
+}
+
+void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
+	glViewport(0, 0, width, height);
+}
+
 int main(void) {
-	printf("Hello World");
+	printf("Hello World!\n");
+
+	glfwInit();
+	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
+	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+
+	GLFWwindow *window = glfwCreateWindow(800, 600, "Computergrafik 1", NULL, NULL);
+
+	if (!window) {
+		printf("Failed to create window\n");
+		glfwTerminate();
+		return -1;
+	}
+
+
+	glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
+	glfwMakeContextCurrent(window);
+
+	glewInit();
+
+	init();
+
+	while (!glfwWindowShouldClose(window)) {
+		draw();
+
+		glfwSwapBuffers(window);
+		glfwPollEvents();
+	}
+
+	glfwTerminate();
+
 	return 0;
 }
\ No newline at end of file