Code from slides

OpenGL laboratories 1
  • Vertex pipeline configuration
    • Assign identity matrix to matrix variable M 
      glm::mat4 M=glm::mat4(1.0f);
    • Compute view matrix V 
      glm::mat4 V=glm::lookAt(
glm::vec3(0.0f,0.0f,-5.0f),
glm::vec3(0.0f,0.0f,0.0f),
glm::vec3(0.0f,1.0f,0.0f));
    • Compute perspective projection matrix 
      glm::mat4 P=glm::perspective(50.0f*PI/180.0f, 1.0f, 1.0f, 50.0f);
    • Load model, view and projection matrices into the shader program 
      spConstant->use();//Activate shader program
glUniformMatrix4fv(spConstant->u("P"),1,false,glm::value_ptr(P));
glUniformMatrix4fv(spConstant->u("V"),1,false,glm::value_ptr(V));
glUniformMatrix4fv(spConstant->u("M"),1,false,glm::value_ptr(M));
  • Animation
    • Declaration 
      //Global variable declaration
float speed=360; //360 degrees/s
    • drawScene procedure (choose onlyu appropriate fragments) 
      void drawScene(GLFWwindow* window,float angle) {
//……
mat4 M=mat4(1.0f);
M=rotate(M,angle,vec3(0.0f,1.0f,0.0f));
//……
Models::torus.drawWire();
}
    • Main loop changes in main function 
      float angle=0;
glfwSetTime(0);
while (!glfwWindowShouldClose(window)) {
angle+=speed*glfwGetTime();
glfwSetTime(0);
drawScene(window,angle);
glfwPollEvents();
}
  • Load model, view and projection matrices into another shader program 
    spLambert->use();//Activate shader program
glUniform4f(spLambert->u("color"),0,1,0,1);
glUniformMatrix4fv(spLambert->u("P"),1,false,glm::value_ptr(P));
glUniformMatrix4fv(spLambert->u("V"),1,false,glm::value_ptr(V));
glUniformMatrix4fv(spLambert->u("M"),1,false,glm::value_ptr(M));
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OpenGL laboratories 2
  • Key processing 
    void key_callback(GLFWwindow* window, int key,
int scancode, int action, int mods){
if (action == GLFW_PRESS) {
if (key == GLFW_KEY_A) printf("A \n");
if (key == GLFW_KEY_D) printf("D \n");
if (key == GLFW_KEY_W && (mods & GLFW_MOD_ALT)!=0) printf("ALT+W\n");
}

if (action == GLFW_RELEASE) {
if (key == GLFW_KEY_W) printf("puszczone W\n");
}
}
  • key_callback procedure registration 
    glfwSetKeyCallback(window, key_callback);
OpenGL laboratories 3
  • glDrawArrays example 1 
       //Model description
   //vertex coordinate array
   float verts[]={ 
      0, 1,0,1,
     -1,-1,0,1,
      1,-1,0,1
   };
   int vertexCount=3; //Number of vertices

   //Drawing code
   spConstant->use();
   glUniformMatrix4fv(spConstant->u("P"),1,false,glm::value_ptr(P));
   glUniformMatrix4fv(spConstant->u("V"),1,false,glm::value_ptr(V));
   glUniformMatrix4fv(spConstant->u("M"),1,false,glm::value_ptr(M));
   glUniform4f(spConstant->u("color"),1,0,0,1);

   glEnableVertexAttribArray(spConstant->a("vertex"));
   glVertexAttribPointer(spConstant->a("vertex"),4,GL_FLOAT,false,0,verts);

   glDrawArrays( GL_TRIANGLES, 0, vertexCount );

   glDisableVertexAttribArray(spConstant->a("vertex"));
  • glDrawArrays example 2 
    //Model description
//Vertex coordinate array
float verts[]={
  0,4.08,0,1,     0,0,2.88,1,
  0,4.08,0,1,     2.5,0,-1.44,1,
  0,4.08,0,1,    -2.5,0,-1.44,1,
  0,0,2.88,1,    -2.5,0,-1.44,1,
  0,0,2.88,1,     2.5,0,-1.44,1,
  -2.5,0,-1.44,1, 2.5,0,-1.44,1
};
int vertexCount=12;

///Drawing code
spConstant->use();
glUniformMatrix4fv(spConstant->u("P"),1,false,glm::value_ptr(P));
glUniformMatrix4fv(spConstant->u("V"),1,false,glm::value_ptr(V));
glUniformMatrix4fv(spConstant->u("M"),1,false,glm::value_ptr(M));
glUniform4f(spConstant->u("color"),0,1,0,1);

glEnableVertexAttribArray(spConstant->a("vertex"));
glVertexAttribPointer(spConstant->a("vertex"),4,GL_FLOAT,false,0,verts);

glDrawArrays( GL_LINES, 0, vertexCount );

glDisableVertexAttribArray(spConstant->a("vertex"));
  • glDrawArrays example 3 
    //Model description
//Vertex coordinate array
float verts[]={
  0,4.08,0,1,     0,0,2.88,1,    -2.5,0,-1.44,1,
  0,4.08,0,1,     0,0,2.88,1,     2.5,0,-1.44,1,
  0,4.08,0,1,     2.5,0,-1.44,1, -2.5,0,-1.44,1,
  2.5,0,-1.44,1, -2.5,0,-1.44,1,  0,0,2.88,1};
//Vertex color array
float colors[]={
  1,0,0,1,  1,0,0,1,  1,0,0,1,
  0,1,0,1,  0,1,0,1,  0,1,0,1,
  0,0,1,1,  0,0,1,1,  0,0,1,1,
  1,1,0,1,  1,1,0,1,  1,1,0,1};
int vertexCount=12;

//Drawing code
spColored->use();
glUniformMatrix4fv(spColored->u("P"),1,false,glm::value_ptr(P));
glUniformMatrix4fv(spColored->u("V"),1,false,glm::value_ptr(V));
glUniformMatrix4fv(spColored->u("M"),1,false,glm::value_ptr(M));

glEnableVertexAttribArray(spColored->a("vertex"));
glVertexAttribPointer(spColored->a("vertex"),4,GL_FLOAT,false,0,verts);

glEnableVertexAttribArray(spColored->a("color"));
glVertexAttribPointer(spColored->a("color"),4,GL_FLOAT,false,0,colors);

glDrawArrays( GL_TRIANGLES, 0, vertexCount );

glDisableVertexAttribArray(spColored->a("vertex"));
glDisableVertexAttribArray(spColored->a("color"));
  • glDrawElements example 
    //Model description
//Vertex coordinate array
float verts[]={
  0,4.08,0,1,     0,0,2.88,1,   -2.5,0,-1.44,1,    2.5,0,-1.44,1};
//Vertex color array
float colors[]={
  1,0,0,1,  0,1,0,1,  0,0,1,1,  1,1,0,1};
//Index array
unsigned int indexes[] ={
  0,1,2,  0,1,3,  0,2,3,  3,2,1};
int indexCount=12;
int vertexCount=4;


//Drawing code
spColored->use();
glUniformMatrix4fv(spColored->u("P"),1,false,glm::value_ptr(P));
glUniformMatrix4fv(spColored->u("V"),1,false,glm::value_ptr(V));
glUniformMatrix4fv(spColored->u("M"),1,false,glm::value_ptr(M));

glEnableVertexAttribArray(spColored->a("vertex"));
glVertexAttribPointer(spColored->a("vertex"),4,GL_FLOAT,false,0,verts);

glEnableVertexAttribArray(spColored->a("color"));
glVertexAttribPointer(spColored->a("color"),4,GL_FLOAT,false,0,colors);

glDrawElements(GL_TRIANGLES,indexCount, GL_UNSIGNED_INT,indexes);

glDisableVertexAttribArray(spColored->a("vertex"));
glDisableVertexAttribArray(spColored->a("color"));
  • Reading texture 
    GLuint tex; //Handle – global declaration

//Function for reading texture files
GLuint readTexture(char* filename) {	
  GLuint tex;	
  glActiveTexture(GL_TEXTURE0); 	

  //Read into computers memory
  std::vector<unsigned char> image;   //Allocate data structure for the image
  unsigned width, height;   //Variables, which will be set to image dimensions
  //Read image
  unsigned error = lodepng::decode(image, width, height, filename);
 
  //Import to graphics card memory
  glGenTextures(1,&tex); //Initialize a handle
  glBindTexture(GL_TEXTURE_2D, tex); //Activate the handle
  //Copy image from computers memory to graphics cards memory
  glTexImage2D(GL_TEXTURE_2D, 0, 4, width, height, 0,
    GL_RGBA, GL_UNSIGNED_BYTE, (unsigned char*) image.data());	

  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);	

  return tex;
} 

//Reading and import of a concrete image, include in initOpenGLProgram
tex=readTexture("bricks.png");

//Remove texture from graphics card memory, include in freeOpenGLProgram
glDeleteTextures(1,&tex);
  • Drawing of a textured model 
    //Model description
//Vertex coordinate array
float verts[]={
  1.0f,-1.0f,0.0f,1.0f, //A
 -1.0f, 1.0f,0.0f,1.0f, //B
 -1.0f,-1.0f,0.0f,1.0f, //C

  1.0f,-1.0f,0.0f,1.0f, //A
  1.0f, 1.0f,0.0f,1.0f, //D
 -1.0f, 1.0f,0.0f,1.0f, //B
};

//TExturing coordinate array
float texCoords[]={
  1.0f, 0.0f,	//A
  0.0f, 1.0f,    //B
  0.0f, 0.0f,    //C

  1.0f, 0.0f,    //A
  1.0f, 1.0f,    //D
  0.0f, 1.0f,    //B
};

//Number of vertices
int vertexCount=6;

//Drawing code
spTextured->use();
glUniformMatrix4fv(spTextured->u("P"),1,false,glm::value_ptr(P));
glUniformMatrix4fv(spTextured->u("V"),1,false,glm::value_ptr(V));
glUniformMatrix4fv(spTextured->u("M"),1,false,glm::value_ptr(M));

glEnableVertexAttribArray(spTextured->a("vertex"));
glVertexAttribPointer(spTextured->a("vertex"),4,GL_FLOAT,false,0,verts);

glEnableVertexAttribArray(spTextured->a("texCoord"));
glVertexAttribPointer(spTextured->a("texCoord"),2,GL_FLOAT,false,0,texCoords);

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,tex);
glUniform1i(spLambertTextured->u("tex"),0);

glDrawArrays( GL_TRIANGLES, 0, vertexCount );

glDisableVertexAttribArray(spTextured->a("vertex"));
glDisableVertexAttribArray(spTextured->a("texCoord"));
  • Drawing of textured and shaded model 
    //Model description
//Vertex coordinate array
float verts[]={
  1.0f,-1.0f,0.0f,1.0f, //A
 -1.0f, 1.0f,0.0f,1.0f, //B
 -1.0f,-1.0f,0.0f,1.0f, //C

  1.0f,-1.0f,0.0f,1.0f, //A
  1.0f, 1.0f,0.0f,1.0f, //D
 -1.0f, 1.0f,0.0f,1.0f}; //B
//Texturing coordinate array
float texCoords[]={
  1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, //ABC
  1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, //ADB
};
//Normal vector array
float normals[]={
  0.0f,0.0f,1.0f,0.0f, //A
  0.0f,0.0f,1.0f,0.0f, //B
  0.0f,0.0f,1.0f,0.0f, //C

  0.0f,0.0f,1.0f,0.0f, //A
  0.0f,0.0f,1.0f,0.0f, //D
  0.0f,0.0f,1.0f,0.0f, //B
};

//Number of vertices
int vertexCount=6;

//Drawing code
glEnableVertexAttribArray(spLambertTextured->a("vertex"));
glVertexAttribPointer(spLambertTextured->a("vertex"),4,GL_FLOAT,false,0,verts);

glEnableVertexAttribArray(spLambertTextured->a("normal"));
glVertexAttribPointer(spLambertTextured->a("normal"),4,GL_FLOAT,false,0,normals);

glEnableVertexAttribArray(spLambertTextured->a("texCoord"));
glVertexAttribPointer(spLambertTextured->a("texCoord"),2,GL_FLOAT,false,0,texCoords);

glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D,tex);
glUniform1i(spLambertTextured->u("tex"),0);

glDrawArrays( GL_TRIANGLES, 0, vertexCount );
glDisableVertexAttribArray(spLambertTextured->a("vertex"));
glDisableVertexAttribArray(spLambertTextured->a("normal"));
glDisableVertexAttribArray(spLambertTextured->a("texCoord"));
OpenGL laboratories 6
  • Reading texture 
    GLuint tex0; //Handle – global declaration

//Function for reading texture files
GLuint readTexture(const char* filename) {	
  GLuint tex;	
  glActiveTexture(GL_TEXTURE0); 	

  //Read into computers memory
  std::vector<unsigned char> image;   //Allocate data structure for the image
  unsigned width, height;   //Variables, which will be set to image dimensions
  //Read image
  unsigned error = lodepng::decode(image, width, height, filename);
 
  //Import to graphics card memory
  glGenTextures(1,&tex); //Initialize a handle
  glBindTexture(GL_TEXTURE_2D, tex); //Activate the handle
  //Copy image from computers memory to graphics cards memory
  glTexImage2D(GL_TEXTURE_2D, 0, 4, width, height, 0,
    GL_RGBA, GL_UNSIGNED_BYTE, (unsigned char*) image.data());	

  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);	

  return tex;
} 

//Reading and import of a concrete image, include in initOpenGLProgram
tex0=readTexture("metal.png");

//Remove texture from graphics card memory, include in freeOpenGLProgram
glDeleteTextures(1,&tex0);
  • Setting up the attribute texCoord0 
    
//In drawScene
glEnableVertexAttribArray(sp->a("texCoord0"));
…
glVertexAttribPointer(sp->a("texCoord0"),
	2,GL_FLOAT,false,0,texCoords);//an appropriate array
…
glDisableVertexAttribArray(sp->a("texCoord0"));
  • Configure sampler variable 
    glUniform1i(sp->u("textureMap0"),0); //drawScene
  • Configure texturing unit 
    glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,tex0);