use perspective to enter into 3d.

src/main.cc

@@ -230,6 +230,18 @@ int main() {
 
 		shader.activate();
 
+		// the model matrix. this rotates the plane on the x axis by -55 degrees.
+		glm::mat4 model(1.0f);
+		model = glm::rotate(model, glm::radians(-55.0f), glm::vec3(1.0f, 0.0f, 0.0f));
+
+		// the view matrix. this moves the "camera" back by 3 units.
+		glm::mat4 view(1.0f);
+		view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
+
+		// the projection matrix. the fov is 45 degrees. the aspect is 800/600 (4:3). the near plane is 0.1 units. the far plane is 100 units.
+		glm::mat4 projection;
+		projection = glm::perspective(glm::radians(45.0f), 800.0f / 600.0f, 0.1f, 100.0f);
+
 		// create the identity matrix
 		glm::mat4 trans(1);
 		// translate it by this vector3
@@ -237,7 +249,9 @@ int main() {
 		// rotate by the z axis with the angle being controlled by time
 		trans = glm::rotate(trans, (float)glfwGetTime(), glm::vec3(0.0f, 0.0f, 1.0f));
 
-		shader.setMat4("transform", trans);
+		shader.setMat4("model", model);
+		shader.setMat4("view", view);
+		shader.setMat4("projection", projection);
 
 		if (!rectangleToggled) {
 			// Bind the state to use the vertexArrayObject object so OpenGL knows what to do with the verticies.

src/vertex.glsl

@@ -7,10 +7,13 @@ layout (location = 2) in vec2 aTexCoord;
 out vec3 ourColor;
 out vec2 TexCoord;
 
-uniform mat4 transform;
+uniform mat4 model;
+uniform mat4 view;
+uniform mat4 projection;
 
 void main() {
-	gl_Position = transform * vec4(aPos, 1.0);
+	// matrix multiplication goes from right to left.
+	gl_Position = projection * view * model * vec4(aPos, 1.0);
 	ourColor = aColor;
 	TexCoord = aTexCoord;
 }