Add light to texture

In this example we add light to a textured cube, we also calculate the normal for each cube surface. You will notice that the shading is flat and this because we define only one normal vertex for the surface. To achieve smooth shading you must define normal for all polygon vertices using openGL.
cpp code

#include <stdlib.h>
#include <GL/glut.h>
#include<math.h>
 #include<windows.h>
#include "RgbImage.h"
GLfloat xRotated, yRotated, zRotated;
GLuint	texture[3];			// Storage For One Texture ( NEW )
GLfloat qaGreen[] = {0.0, 1.0, 0.0, 1.0}; //Green Color
GLfloat qaWhiteAM[] = {1.0, 1.0, 1.0, 1.0}; //White Ambient Material Color
GLfloat qaWhiteDF[] = {1.0, 1.0, 1.0, 1.0}; //White Diffuse Material Color
GLfloat qaWhite[] = {1.0, 1.0, 1.0, 1.0}; //White Color
GLfloat NormalX=0;
GLfloat NormalY=0;
GLfloat NormalZ=0;

    // Set lighting intensity and color
GLfloat qaAmbientLight[]    = {0.2, 0.2, 0.2, 1.0};// Whilte Ambient Light
GLfloat qaDiffuseLight[]    = {1, 0.9, 1, 1.0}; // Whilte Diffuse Light
GLfloat qaSpecularLight[]    = {1.0, 1.0, 1.0, 1.0}; // White Specular Light
 
    // Light source position
GLfloat qaLightPosition[]    = {3, 0, 0, 0};
/*
* Read a texture map from a BMP bitmap file.
*/
void CalcNormal(GLfloat point1_x,GLfloat point1_y,GLfloat point1_z,GLfloat point2_x,GLfloat 


point2_y,GLfloat point2_z,GLfloat point3_x,GLfloat point3_y,GLfloat point3_z)
 {
	  // Calculate vectors
	  GLfloat value1_x = point2_x - point1_x;
	  GLfloat value1_y = point2_y - point1_y;
	  GLfloat value1_z = point2_z - point1_z;
	 
	  GLfloat value2_x = point3_x - point1_x;
	  GLfloat value2_y = point3_y - point1_y;
	  GLfloat value2_z = point3_z - point1_z;
  
  	// Get cross product of vectors
  	NormalX = (value1_y * value2_z) - (value2_y * value1_z);
	NormalY = (value1_z * value2_x) - (value2_z * value1_x);
  	NormalZ = (value1_x * value2_y) - (value2_x * value1_y);

	// Normalise final vector
  	float vLen = sqrt( (NormalX * NormalX) + (NormalY * NormalY) + (NormalZ * NormalZ) );

	NormalX = (float)NormalX/vLen;
	NormalY = (float)NormalY/vLen;
  	NormalZ = (float)NormalZ/vLen;
 
	 
 }
void initLighting()
{

    // Enable lighting
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);

     // Set lighting intensity and color
      glLightfv(GL_LIGHT0, GL_AMBIENT, qaAmbientLight);
      glLightfv(GL_LIGHT0, GL_DIFFUSE, qaDiffuseLight);
      glLightfv(GL_LIGHT0, GL_SPECULAR, qaSpecularLight);
    
    // Set the light position
      glLightfv(GL_LIGHT0, GL_POSITION, qaLightPosition);

}
void loadTextureFromFile(char *filename,int index)
{   
   glClearColor (0.0, 0.0, 0.0, 0.0);
  
   glEnable(GL_DEPTH_TEST);

   RgbImage theTexMap( filename );

  glGenTextures(1, &texture[index]);					// Create The Texture
   glBindTexture(GL_TEXTURE_2D, texture[index]);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 
 
		// Typical Texture Generation Using Data From The Bitmap
	
		glTexImage2D(GL_TEXTURE_2D, 0, 3, theTexMap.GetNumCols(), theTexMap.GetNumRows(), 1, GL_RGB, GL_UNSIGNED_BYTE, theTexMap.ImageData() );

}

/*
* Draw the texture in the OpenGL graphics window
*/
void drawScene(void)
{
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glEnable(GL_TEXTURE_2D);
  	
   glLoadIdentity();
   glTranslatef(0.0,0.0,-5);
  
      glLightfv(GL_LIGHT0, GL_POSITION, qaLightPosition);


  glPushMatrix();
  
	glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, qaWhiteAM);
    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, qaWhiteDF);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, qaWhite);
    glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, 20);

     glRotatef(yRotated, 0, 1, 0);
	 glRotatef(zRotated, 0, 0, 1);
  glBindTexture(GL_TEXTURE_2D, texture[0]);
  glBegin(GL_QUADS);
		// Front Face
      
		CalcNormal(-1.0f, -1.0f,  1.0f, 1.0f, -1.0f,  1.0f,-1.0f,  1.0f,  1.0f);
		glNormal3f(NormalX,NormalY,NormalZ);
		glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);
		glTexCoord2f(2.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);
		glTexCoord2f(2.0f, 2.0f); glVertex3f( 1.0f,  1.0f,  1.0f);
		glTexCoord2f(0.0f, 2.0f); glVertex3f(-1.0f,  1.0f,  1.0f);
		// Back Face
		CalcNormal(-1.0f, -1.0f, -1.0f,-1.0f,  1.0f, -1.0f, 1.0f, -1.0f, -1.0f);
		 glNormal3f(NormalX,NormalY,NormalZ);
       
		glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
		glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);
		glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);
		glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
  glEnd();
   
 
  glBindTexture(GL_TEXTURE_2D, texture[1]);
  glBegin(GL_QUADS);
		// Top Face
		//glBindTexture(GL_TEXTURE_2D, texture[1]);
  	    CalcNormal( -1.0f,  1.0f, -1.0f,-1.0f,  1.0f,  1.0f,1.0f,  1.0f, -1.0f);
        glNormal3f(NormalX,NormalY,NormalZ);
		glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);
		glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,  1.0f,  1.0f);
		glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,  1.0f,  1.0f);
		glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);
		// Bottom Face
		 CalcNormal(-1.0f, -1.0f, -1.0f,1.0f, -1.0f, -1.0f,-1.0f, -1.0f,  1.0f);
	    glNormal3f(NormalX,NormalY,NormalZ);
		glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
		glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
		glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);
		glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);
		// Right face
		  CalcNormal(  1.0f, -1.0f, -1.0f, 1.0f,  1.0f, -1.0f,1.0f, -1.0f,  1.0f);
		 glNormal3f(NormalX,NormalY,NormalZ);
		glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f);
		glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f,  1.0f, -1.0f);
		glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,  1.0f,  1.0f);
		glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f,  1.0f);
  glEnd();
      

 
  glBindTexture(GL_TEXTURE_2D, texture[2]);
	glBegin(GL_QUADS);
		// Left Face
		 glBindTexture(GL_TEXTURE_2D, texture[2]);
	   CalcNormal(-1.0f, -1.0f, -1.0f,-1.0f, -1.0f,  1.0f,-1.0f,  1.0f, -1.0f);
	    glNormal3f(NormalX,NormalY,NormalZ);
		glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f);
		glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f,  1.0f);
		glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f,  1.0f,  1.0f);
		glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f,  1.0f, -1.0f);
	glEnd();
  glPopMatrix();


   glFlush();
   glDisable(GL_TEXTURE_2D);
  
}

void resizeWindow(int x, int y)
{
 if (y == 0 || x == 0) return;  //Nothing is visible then, so return
    //Set a new projection matrix
    glMatrixMode(GL_PROJECTION);  
    glLoadIdentity();
    //Angle of view:40 degrees
    //Near clipping plane distance: 0.5
    //Far clipping plane distance: 20.0
     
    gluPerspective(40.0,(GLdouble)x/(GLdouble)y,0.5,20.0);
    glMatrixMode(GL_MODELVIEW);
    glViewport(0,0,x,y);  //Use the whole window for rendering
}

void keyboard (unsigned char key, int x, int y)
{
   switch (key) {
      case 27:
         exit(0);
         break;
      default:
         break;
   }
}

char* filename[] = {"./salt_on_spoon.bmp","./win030.bmp","./win044.bmp"};

void idleFunc(void)
{
 
     yRotated += 0.01;
     zRotated += 0.01;
    drawScene();
}
int main(int argc, char** argv)
{
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
   glutInitWindowSize(240, 240);
   glutInitWindowPosition(100, 100);
   glutCreateWindow(argv[0]);
   for ( int  i=0;i<3;i++)
   {
	  loadTextureFromFile(filename[i],i);
   }
   initLighting();
   glutDisplayFunc(drawScene);
   glutReshapeFunc(resizeWindow);
   glutKeyboardFunc(keyboard);
     glutIdleFunc(idleFunc);
   glutMainLoop();
   return 0;
}

You will find missing files for reading the texture image in the previous example

Code:

http://www.codemiles.com/c-opengl-examples/using-many-textures-t9272.html


Attachments

LightTexture.png (46.85 KiB) Viewed 9331 times