Code Target

Texture mapping is a technique that allows us to map image data onto a triangle, thereby enabling us to increase the details and realism of our scene significantly.

A 2D texture is a matrix of data elements. One use for 2D textures is to store 2D image data, where each element in the texture stores the color of a pixel. However, this is not the only usage. For example, in an advanced technique called normal mapping, each element in the texture stores a 3D vector instead of a color. Therefore, although it is common to think of textures as storing image data, they are really more general purpose than that. A 1D texture is like a 1D array of data elements, and a 3D texture is like a 3D array of data elements. Direct3D uses a texture coordinate system that consists of a u-axis that runs horizontally to the image and a v-axis that runs vertically to the image. The coordinates, (u, v) such that 0 ≤ u, v ≤ 1, identify an element on the texture called a texel.
 
For each 3D triangle, we want to define a corresponding triangle on the texture that is to be mapped onto the 3D triangle. Let p0, p1, and p2 be the vertices of a 3D triangle with respective texture coordinates q0, q1, and q2. For an arbitrary point (x, y, z) on the 3D triangle, its texture coordinates (u, v) are found by linearly interpolating the vertex texture coordinates across the 3D triangle by the same s, t parameters.
 
(x, y, z) = p = p0 + s (p1 – p0) + t (p2 – p0) for s ≥ 0, t ≥ 0, s + t ≤ 1 then,
(u, v) = q = q0 + s(q1 – q0) + t(q2 – q0)
In this way, every point on the triangle has a corresponding texture coordinate.

 Solution:
 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using Microsoft.DirectX;
using Microsoft.DirectX.Direct3D;
namespace Gp_prac3
{
public partial class Form1 : Form
{
private Microsoft.DirectX.Direct3D.Device device;
private CustomVertex.PositionTextured[] vertex = new CustomVertex.PositionTextured[3];
private Texture texture;
public Form1()
{
InitializeComponent();
InitDevice();
}
private void InitDevice()

{
PresentParameters pp = new PresentParameters();
pp.Windowed = true;
pp.SwapEffect = SwapEffect.Discard;
device = new Device(0,DeviceType .Hardware ,this, CreateFlags.HardwareVertexProcessing, pp);
device.Transform.Projection = Matrix.PerspectiveFovLH(3.14f / 4, device.Viewport.Width / device.Viewport.Height, 1f, 1000f);
device.Transform.View = Matrix.LookAtLH(new Vector3(0, 0, 20), new Vector3(),
new Vector3(0, 1, 0));
device.RenderState.Lighting = false;
vertex[0] = new CustomVertex.PositionTextured(new Vector3(0, 0, 0), 0, 0);
vertex[1] = new CustomVertex.PositionTextured(new Vector3(5, 0, 0), 0, 1);
vertex[2] = new CustomVertex.PositionTextured(new Vector3(0, 5, 0),-1, 1);
texture=new Texture (device,new Bitmap ("E:\\TYCS\\images\\img1.jpg"), 0,
Pool.Managed );
}
private void Form1_Load(Object sender, EventArgs e)
{ }
private void Form1_Paint(Object sender, PaintEventArgs e)
{
device.Clear(ClearFlags.Target, Color.CornflowerBlue, 1, 0);
device.BeginScene();
device.SetTexture(0,texture);
device.VertexFormat = CustomVertex.PositionTextured.Format;
device.DrawUserPrimitives(PrimitiveType.TriangleList, vertex.Length / 3, vertex);
device.EndScene();
device.Present();
}
}
}

Output: