Opentk Tutorial 4---Draw Quad

 

Opentk チュートリアル 4---クワッドの描画

Opentk 튜토리얼 4---쿼드 그리기

Opentk 教學4--畫四邊形

Releate object:

Quad_VBO

Shader

How to use?

        //Window_Load

    Quad.init_shader();
    quad = new Quad();
    quad.set_color(0, 1, 0, 1f);       
    quad.set_width_height(0.5f, 0.5f);
    quad.set_xy(0.1f, 0.5f);

    //Render

   GL.Viewport(0,0,this.Size.X,this.Size.Y);
   GL.Clear(ClearBufferMask.ColorBufferBit); 
   Quad.use_shader();
   quad.draw();
   this.SwapBuffers();

    //Release

 Quad.release_shader();
 quad.release();

using OpenTK.Graphics.OpenGL4;
using OpenTK.Mathematics;
 
 
public class Quad
{
 
 
    private static Shader shader;
 
    public static void use_shader()
    {
        shader.Use();
    }
    public static void init_shader()
    {
        String vert = "#version 330\n" +
            "layout (location = 0) in  vec2 aPosition;\n"+
            "layout (location = 1) in lowp vec4 aColor;\n" +
            "out lowp vec4 color;\n" +
            "void main()" +
            "{" +
            "  color=aColor;" +
            "  gl_Position = vec4(aPosition,0.0, 1.0);" +
            "}";
 
        String frag = "#version 330\n" +
             "precision highp float;" +
            "in  lowp vec4 color;\n" +
            "out lowp vec4 FragColor;\n" +
            "void main(){" +
            "FragColor =color;"+
            "}";
 
         shader = new Shader(vert, frag);
 
 
    }
    public static void release_shader()
    {
        shader.Delete();
        shader = null;
    }
 
 
    private int vao;
    private Quad_VBO  quad_vbo;
    public Quad()
    {
        if (shader == null)
        {
            throw new Exception("Please init shader.");
        }
        quad_vbo = new Quad_VBO();
        quad_vbo.Create_vbo();
        vao = GL.GenVertexArray();
 
        GL.BindVertexArray(vao);
        GL.BindBuffer(BufferTarget.ArrayBuffer, quad_vbo.vbo);
        GL.VertexAttribPointer(0, 2, VertexAttribPointerType.Float, false, 6 * sizeof(float), 0);
        GL.EnableVertexAttribArray(0);
        GL.VertexAttribPointer(1, 4, VertexAttribPointerType.Float, false, 6 * sizeof(float), 8);
        GL.EnableVertexAttribArray(1);
        GL.BindVertexArray(0);
    }
 
    //gl_position range=(-1~1)
    public void set_xy(float x,float y)
    {
        float w = get_width();
        float h= get_height();
        quad_vbo.set_xywh(x*2-1,y*2-1,w,h);
        quad_vbo.Update_vbo();
    }
 
    public void set_width_height(float w,float h)
    {
        float x = get_x();
        float y = get_y();
        quad_vbo.set_xywh(x, y, w*2, h*2);
        quad_vbo.Update_vbo();
    }
 
    public float get_x()
    {
        return quad_vbo.vertices[0];
    }
 
    public float get_y()
    {
        return quad_vbo.vertices[1];
    }
 
    public float get_width()
    {
        return quad_vbo.vertices[6] - quad_vbo.vertices[0];
    }
    public float get_height()
    {
        return quad_vbo.vertices[13] - quad_vbo.vertices[1];
    }
 
    public Vector4 get_color()
    {
        return new Vector4(quad_vbo.vertices[2], quad_vbo.vertices[3], quad_vbo.vertices[4], quad_vbo.vertices[5]);
    }
 
    public void set_color(float r, float g, float b,float a)
    {
        quad_vbo.set_color_all(r, g, b, a);
        quad_vbo.Update_vbo();
    }
 
    public void draw()
    {
        GL.BindVertexArray(vao);
        GL.DrawArrays(PrimitiveType.TriangleFan, 0, 4);
    }
 
    public void release()
    {
        GL.DeleteVertexArray(vao);
        quad_vbo.Delete_vbo();
    }
}