Creating a Simple 3D Game with XNA/Adding a Sky Sphere
Creating your SkySphere Renderer
[edit | edit source]In order to render the skysphere, we will create a new rendering class similar to the one used to render the fish, but modified to allow the model to render without an armature structure in place. First, create a new class file by right clicking on your project, selecting 'Add'/'New Item' and selecting 'Class'. Change the class and file name to 'GenericModelRenderer'.
Change the default using statements to the following.
using System;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using SkinnedModel;
And ensure that the class is using the XNA namespace by affixing the class name with
: Microsoft.Xna.Framework.Game
.
Add the following class variables and constructor. public Model currentModel; public Vector3 Translation = new Vector3(0, 0, 0); public Vector3 Rotation = new Vector3(0, 0, 0); public float Scale = 1.0f;
public GenericModelRenderer(Model currentModelInput)
{
currentModel = currentModelInput;
}
Unlike the previous code, much less initialisation is required as we do not need to initialise the animation player. You'll see a similar trend with this classes equivalent to the 'ModelDraw' method.
public void ModelDraw(GraphicsDevice device, Vector3 cameraPosition, Vector3 cameraTarget, float farPlaneDistance)
{
Matrix[] transforms = new Matrix[currentModel.Bones.Count];
currentModel.CopyAbsoluteBoneTransformsTo(transforms);
// Compute camera matrices.
Matrix view = Matrix.CreateLookAt(cameraPosition, cameraTarget, Vector3.Right);
//Calculate the aspect ratio, set the aspect axis and screen zoom.
int aspectConstraint = 1; /* 0 = Maintain Vertical FOV, 1 = Conditional Aspect Ratio, 2 = Maintain Horizontal FOV */
float aspectRatio = (float)device.Viewport.Width / (float)device.Viewport.Height;
float aspectOrigin = 16.0f / 9.0f; /* Aspect ratio condition in which changes axis direction if the current display is below this. Default is 1. */
float zoomFactor = 1.0f;
switch (aspectConstraint)
{
case 1:
if (aspectRatio < aspectOrigin)
{
zoomFactor = zoomFactor * (aspectRatio / aspectOrigin);
}
break;
case 2:
zoomFactor = zoomFactor * (aspectRatio / aspectOrigin);
break;
}
Matrix projection = Matrix.CreatePerspectiveFieldOfView(2.0f * Math.Atan(Math.Tan(MathHelper.ToRadians(45.0f / 2.0f) / zoomFactor), aspectRatio, 1.0f, farPlaneDistance);
// Draw the model. A model can have multiple meshes, so loop.
foreach (ModelMesh mesh in currentModel.Meshes)
{
// This is where the mesh orientation is set, as well as our camera and projection.
foreach (BasicEffect effect in mesh.Effects)
{
effect.World = transforms[mesh.ParentBone.Index] *
Matrix.CreateRotationX(Rotation.X) *
Matrix.CreateRotationY(Rotation.Y) *
Matrix.CreateRotationZ(Rotation.Z) *
Matrix.CreateScale(Scale) *
Matrix.CreateWorld(Translation, Vector3.Forward, Vector3.Up);
effect.View = view;
effect.Projection = projection;
}
mesh.Draw();
}
}
Notice that the draw method uses the same arguments as the other fish code, can be used in more or less the same way.
Using Your Renderer
[edit | edit source]Place a new folder in your models folder called 'SkySphere', and add your model and texture. Go back into your main 'Game1' file, and add the new class variable
GenericModelRenderer SkySphere; //Your SkySphere model
.
Go into your LoadContent file, and add the following lines to initialise the class and set up the model for rendering.
currentModel = Content.Load<Model>("Models\\SkySphere\\SkyModel");
SkySphere = new GenericModelRenderer(currentModel);//Add the skysphere
And in the draw method, add the following line about the same place as your fish models draw method.
SkySphere.ModelDraw(GraphicsDevice, cameraPosition, cameraTarget, farPlaneDistance);
Render the code, and if you're set up is the same as mine, you should see a screen like this.
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You might notice this isn't quite what we need. We can adjust the position and the scale by adjusting the public variables in the SkySphere class. In my case, I added the following changes after the classes initialisation in the LoadContent() method.
SkySphere.Translation.X = 120.0f;
SkySphere.Translation.Z = 15.0f;
SkySphere.Scale = 30.0f;
Adjust to taste, and you should see a screen similar to mine here.
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