Simple implementation of Unity graphics

Unity is a popular game engine that supports various graphics effects. In Unity, we can use various techniques to achieve amazing graphics effects. This article will introduce some commonly used Unity graphics technologies, and provide related codes and algorithms.

transparency

Transparency refers to how opaque an object is. In Unity, we can control the transparency of an object by changing the alpha channel value of the material. Suppose we have a plane and a translucent red sphere is placed on it. Here is a sample code that demonstrates how to achieve this effect:

using UnityEngine;

public class TransparentDemo : MonoBehaviour
{
    public Material material; //材质球

    void OnRenderObject() //当渲染对象时调用
    {
        material.SetPass(0); //设置渲染使用的材质球的第0个pass
        GL.PushMatrix(); //压入矩阵堆栈
        GL.MultMatrix(transform.localToWorldMatrix); //将本地坐标系转换为世界坐标系
        DrawSphere(); //绘制球体
        GL.PopMatrix(); //从矩阵堆栈中弹出矩阵
    }

    void DrawSphere()
    {
        GL.Begin(GL.TRIANGLES); //开始绘制三角形

        GL.Color(new Color(1.0f, 0.0f, 0.0f, 0.5f)); //设置颜色，其中前三个参数代表颜色的RGB值，最后一个参数代表颜色的透明度

        for (int i = 0; i < 360; i++)
        {
            float x = Mathf.Sin(i * Mathf.Deg2Rad); //通过正弦函数获取x坐标
            float z = Mathf.Cos(i * Mathf.Deg2Rad); //通过余弦函数获取z坐标
            GL.Vertex3(x, 0, z); //绘制顶点，其中y坐标为0
        }
        GL.End(); //结束绘制
    }
}

This code creates a plane and a translucent red ball. In the OnRenderObject method, we set the material of the object and draw the translucent ball using GL library functions.

shadow

Unity supports casting and receiving shadows, which is very important for realistic scenes. In Unity, we can set the light source to produce real-time shadows. We can also set objects to receive real-time shadows. Here is a code sample that demonstrates how to implement shadows in Unity:

using UnityEngine;

public class ShadowDemo : MonoBehaviour
{
    public Light light; //灯光
    public Material material; //材质球

    void OnRenderObject() //当渲染对象时调用
    {
        Matrix4x4 proj = light.projectionMatrix; //获取投影矩阵
        Matrix4x4 view = light.worldToCameraMatrix * transform.localToWorldMatrix; //获取视图矩阵
        Matrix4x4 vp = proj * view; //将投影矩阵和视图矩阵相乘得到最终的变换矩阵
        material.SetMatrix("_LightVP", vp); //将变换矩阵传入材质球的"_LightVP"参数中
    }
}

This code creates a light and an object. In the OnRenderObject method, we set the material of the object, and use the matrix calculation method to calculate the view matrix and projection matrix of the light, so as to achieve the shadow effect.

reflection

Unity supports reflection, which is very important to achieve high-quality scenes. In Unity, we can use reflection textures to simulate the reflection effect of the environment around the object. Here is a code sample that demonstrates how to implement reflection in Unity:

using UnityEngine;

public class ReflectionDemo : MonoBehaviour
{
    public Camera reflectionCamera; //反射相机

    void OnWillRenderObject() //当渲染对象将要被渲染时调用
    {
        //将反射相机的位置和朝向设置为当前物体的位置和朝向
        reflectionCamera.transform.position = transform.position;
        reflectionCamera.transform.rotation = Quaternion.LookRotation(transform.forward, transform.up);

        //计算反射平面的法向量和距离
        Vector4 reflectionPlane = new Vector4(transform.up.x, transform.up.y, transform.up.z, -Vector3.Dot(transform.up, transform.position));

        //计算反射矩阵
        Matrix4x4 reflection = Matrix4x4.zero;
        CalculateReflectionMatrix(ref reflection, reflectionPlane);

        //将反射矩阵和主相机的视图矩阵相乘得到反射相机的视图矩阵
        reflectionCamera.worldToCameraMatrix = Camera.main.worldToCameraMatrix * reflection;

        GL.SetRevertBackfacing(true); //设置渲染面剔除反向面
        reflectionCamera.Render(); //渲染反射到的场景
        GL.SetRevertBackfacing(false); //恢复渲染面剔除设置

        //将反射纹理传入材质球的"_ReflectionTex"参数中
        GetComponent<Renderer>().sharedMaterial.SetTexture("_ReflectionTex", reflectionCamera.targetTexture);
    }

    void CalculateReflectionMatrix(ref Matrix4x4 reflectionMat, Vector4 plane)
    {
        //计算反射矩阵的各个元素
        reflectionMat.m00 = (1.0f - 2.0f * plane[0] * plane[0]);
        reflectionMat.m01 = (-2.0f * plane[0] * plane[1]);
        reflectionMat.m02 = (-2.0f * plane[0] * plane[2]);
        reflectionMat.m03 = 0.0f;

        reflectionMat.m10 = (-2.0f * plane[1] * plane[0]);
        reflectionMat.m11 = (1.0f - 2.0f * plane[1] * plane[1]);
        reflectionMat.m12 = (-2.0f * plane[1] * plane[2]);
        reflectionMat.m13 = 0.0f;

        reflectionMat.m20 = (-2.0f * plane[2] * plane[0]);
        reflectionMat.m21 = (-2.0f * plane[2] * plane[1]);
        reflectionMat.m22 = (1.0f - 2.0f * plane[2] * plane[2]);
        reflectionMat.m23 = 0.0f;

        reflectionMat.m30 = (-2.0f * plane[3] * plane[0]);
        reflectionMat.m31 = (-2.0f * plane[3] * plane[1]);
        reflectionMat.m32 = (-2.0f * plane[3] * plane[2]);
        reflectionMat.m33 = 1.0f;
    }
}

This code creates a reflection camera and an object. In the OnWillRenderObject method, we set the position and rotation of the reflection camera, and use the matrix calculation method to calculate the reflection matrix to achieve the reflection effect.

Summarize

This article introduces some commonly used Unity graphics techniques, including transparency, shadows and reflections. All of the above examples are accompanied by associated code and algorithms. By mastering these techniques, you can achieve amazing graphics in Unity.

Simple implementation of Unity graphics

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