Ever heard of Buffer Streaming

src/main.c

@@ -17,13 +17,23 @@ int main(int argc, char *argv[]) {
 
 	glfwSetKeyCallback(window, &key_pressed);
 
-	float vertices[] = {
+	const float triangle[] = {
 		//pos					// ColorIndecies     //Texture coordnites
 		-0.5f, -0.5f, 0.0f, 	1.0f, 1.0f, 1.0f,	0.0f, 0.0f,
 	 	 0.5f, -0.5f, 0.0f, 	1.0f, 1.0f, 1.0f,	1.0f, 0.0f,
 		 0.0f,  0.5f, 0.0f, 	1.0f, 1.0f, 1.0f,	0.5f, 1.0f
 	};
 
+	const float square[] = {
+		-0.5f, -0.5f, 0.0f, 	1.0f, 1.0f, 1.0f,	0.0f, 0.0f,
+	 	 0.5f, -0.5f, 0.0f, 	1.0f, 1.0f, 1.0f,	1.0f, 0.0f,
+		 0.5f,  0.5f, 0.0f, 	1.0f, 1.0f, 1.0f,	1.0f, 1.0f,	
+		-0.5f,  0.5f, 0.0f,		1.0f, 1.0f, 1.0f,	0.0f, 1.0f,
+	};
+	const unsigned int indices[] = {
+		0, 1 ,2,
+		0, 2, 3
+	};
 	
 	// CreateShader
 	char* vertex1 = "assets/shaders/vertex4.glsl\0";
@@ -32,15 +42,15 @@ int main(int argc, char *argv[]) {
 	shader1 = createShader(vertex1, fragment1);
 
 	// Initialise VBO and VAO
-	unsigned int VAO, VBO;
+	unsigned int VAO, VBO, EBO;
 	glGenVertexArrays(1, &VAO);
 	glGenBuffers(1, &VBO);
-	//unsigned int EBO;
+	glGenBuffers(1, &EBO);
-	//glGenBuffers(1, &EBO);
 
 	glBindVertexArray(VAO);
 	glBindBuffer(GL_ARRAY_BUFFER, VBO);
-	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(square), NULL, GL_STATIC_DRAW);
+
 	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0 );
 	glEnableVertexAttribArray(0);
 	glVertexAttribPointer(1, 3,GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3*sizeof(float)));
@@ -48,28 +58,62 @@ int main(int argc, char *argv[]) {
 	glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
 	glEnableVertexAttribArray(2);
 
+	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
+	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_DYNAMIC_DRAW);
+
+	float *buffer = glMapBuffer(GL_ARRAY_BUFFER, GL_READ_WRITE);
+	memcpy(buffer, triangle, sizeof(triangle));
+	glUnmapBuffer(GL_ARRAY_BUFFER);
+	
 	// Create Texture
 	unsigned int texture;
 	texture = createTexture("assets/textures/wall.jpg");
 
+	unsigned int transformLoc = glGetUniformLocation(shader1, "transform");
+
 	mat4x4 transform;
 	mat4x4_identity(transform);
-
+	bool toogle=false;
+	float prev_time=0, dt=0, timer=0, time=0;
 	while(!glfwWindowShouldClose(window)) {
+		time = glfwGetTime();
+		dt = time - prev_time;
+		prev_time = time;
 
-		glClearColor(0.6f, 0.0f, 0.8f, 0.0f);
+//		printf("dt: %f \n",dt*1000);
+
+		timer += dt;
+		if(timer>= 1.5f){
+			timer=0;
+			buffer = glMapBuffer(GL_ARRAY_BUFFER, GL_READ_WRITE);	
+			if (toogle){
+				memcpy(buffer, triangle,sizeof(triangle));
+				buffer[16]=0.5f;
+			} else {
+				memcpy(buffer, square, sizeof(square));
+				buffer[16]=0.0f;
+			}
+
+			printf("%f ", buffer[16]);
+			glUnmapBuffer(GL_ARRAY_BUFFER);
+			toogle = !toogle;
+		}
+
+		glClearColor(0.6f, 0.0f, 0.7f, 0.0f);
 		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 		glUseProgram(shader1);
-		glActiveTexture(GL_TEXTURE0);
 		glBindTexture(GL_TEXTURE_2D, texture);
 		glBindVertexArray(VAO);
 
 		mat4x4_translate(transform, pos[0], pos[1], pos[2]);
-		unsigned int transformLoc = glGetUniformLocation(shader1, "transform");
 		glUniformMatrix4fv(transformLoc, 1, GL_FALSE, *transform);
 
-		glDrawArrays(GL_TRIANGLES, 0, 3);
+		if(toogle){
+			glDrawArrays(GL_TRIANGLES, 0, 3);
+		} else {
+			glDrawElements(GL_TRIANGLES, 6,GL_UNSIGNED_INT, 0);
+		}
 		
 		glfwSwapBuffers(window);
 		glfwPollEvents();