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Lesson36.cpp
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Lesson36.cpp
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/**************************************
* *
* Jeff Molofee's Basecode Example *
* nehe.gamedev.net *
* 2001 *
* *
* All Code / Tutorial Commenting *
* by Jeff Molofee ( NeHe ) *
* *
**************************************/
#include <windows.h> // Header File For Windows
#include <gl\gl.h> // Header File For The OpenGL32 Library
#include <gl\glu.h> // Header File For The GLu32 Library
#include <gl\glaux.h> // Header File For The GLaux Library
#include "NeHeGL.h" // Header File For NeHeGL
#include <math.h> // We'll Need Some Math
#pragma comment( lib, "opengl32.lib" ) // Search For OpenGL32.lib While Linking
#pragma comment( lib, "glu32.lib" ) // Search For GLu32.lib While Linking
#pragma comment( lib, "glaux.lib" ) // Search For GLaux.lib While Linking
#ifndef CDS_FULLSCREEN // CDS_FULLSCREEN Is Not Defined By Some
#define CDS_FULLSCREEN 4 // Compilers. By Defining It This Way,
#endif // We Can Avoid Errors
GL_Window* g_window;
Keys* g_keys;
// User Defined Variables
float angle; // Used To Rotate The Helix
float vertexes[4][3]; // Holds Float Info For 4 Sets Of Vertices
float normal[3]; // An Array To Store The Normal Data
GLuint BlurTexture; // An Unsigned Int To Store The Texture Number
GLuint EmptyTexture() // Create An Empty Texture
{
GLuint txtnumber; // Texture ID
unsigned int* data; // Stored Data
// Create Storage Space For Texture Data (128x128x4)
data = (unsigned int*)new GLuint[((128 * 128)* 4 * sizeof(unsigned int))];
ZeroMemory(data,((128 * 128)* 4 * sizeof(unsigned int))); // Clear Storage Memory
glGenTextures(1, &txtnumber); // Create 1 Texture
glBindTexture(GL_TEXTURE_2D, txtnumber); // Bind The Texture
glTexImage2D(GL_TEXTURE_2D, 0, 4, 128, 128, 0,
GL_RGBA, GL_UNSIGNED_BYTE, data); // Build Texture Using Information In data
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
delete [] data; // Release data
return txtnumber; // Return The Texture ID
}
void ReduceToUnit(float vector[3]) // Reduces A Normal Vector (3 Coordinates)
{ // To A Unit Normal Vector With A Length Of One.
float length; // Holds Unit Length
// Calculates The Length Of The Vector
length = (float)sqrt((vector[0]*vector[0]) + (vector[1]*vector[1]) + (vector[2]*vector[2]));
if(length == 0.0f) // Prevents Divide By 0 Error By Providing
length = 1.0f; // An Acceptable Value For Vectors To Close To 0.
vector[0] /= length; // Dividing Each Element By
vector[1] /= length; // The Length Results In A
vector[2] /= length; // Unit Normal Vector.
}
void calcNormal(float v[3][3], float out[3]) // Calculates Normal For A Quad Using 3 Points
{
float v1[3],v2[3]; // Vector 1 (x,y,z) & Vector 2 (x,y,z)
static const int x = 0; // Define X Coord
static const int y = 1; // Define Y Coord
static const int z = 2; // Define Z Coord
// Finds The Vector Between 2 Points By Subtracting
// The x,y,z Coordinates From One Point To Another.
// Calculate The Vector From Point 1 To Point 0
v1[x] = v[0][x] - v[1][x]; // Vector 1.x=Vertex[0].x-Vertex[1].x
v1[y] = v[0][y] - v[1][y]; // Vector 1.y=Vertex[0].y-Vertex[1].y
v1[z] = v[0][z] - v[1][z]; // Vector 1.z=Vertex[0].y-Vertex[1].z
// Calculate The Vector From Point 2 To Point 1
v2[x] = v[1][x] - v[2][x]; // Vector 2.x=Vertex[0].x-Vertex[1].x
v2[y] = v[1][y] - v[2][y]; // Vector 2.y=Vertex[0].y-Vertex[1].y
v2[z] = v[1][z] - v[2][z]; // Vector 2.z=Vertex[0].z-Vertex[1].z
// Compute The Cross Product To Give Us A Surface Normal
out[x] = v1[y]*v2[z] - v1[z]*v2[y]; // Cross Product For Y - Z
out[y] = v1[z]*v2[x] - v1[x]*v2[z]; // Cross Product For X - Z
out[z] = v1[x]*v2[y] - v1[y]*v2[x]; // Cross Product For X - Y
ReduceToUnit(out); // Normalize The Vectors
}
void ProcessHelix() // Draws A Helix
{
GLfloat x; // Helix x Coordinate
GLfloat y; // Helix y Coordinate
GLfloat z; // Helix z Coordinate
GLfloat phi; // Angle
GLfloat theta; // Angle
GLfloat v,u; // Angles
GLfloat r; // Radius Of Twist
int twists = 5; // 5 Twists
GLfloat glfMaterialColor[]={0.4f,0.2f,0.8f,1.0f}; // Set The Material Color
GLfloat specular[]={1.0f,1.0f,1.0f,1.0f}; // Sets Up Specular Lighting
glLoadIdentity(); // Reset The Modelview Matrix
gluLookAt(0, 5, 50, 0, 0, 0, 0, 1, 0); // Eye Position (0,5,50) Center Of Scene (0,0,0), Up On Y Axis
glPushMatrix(); // Push The Modelview Matrix
glTranslatef(0,0,-50); // Translate 50 Units Into The Screen
glRotatef(angle/2.0f,1,0,0); // Rotate By angle/2 On The X-Axis
glRotatef(angle/3.0f,0,1,0); // Rotate By angle/3 On The Y-Axis
glMaterialfv(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE,glfMaterialColor);
glMaterialfv(GL_FRONT_AND_BACK,GL_SPECULAR,specular);
r=1.5f; // Radius
glBegin(GL_QUADS); // Begin Drawing Quads
for(phi=0; phi <= 360; phi+=20.0) // 360 Degrees In Steps Of 20
{
for(theta=0; theta<=360*twists; theta+=20.0) // 360 Degrees * Number Of Twists In Steps Of 20
{
v=(phi/180.0f*3.142f); // Calculate Angle Of First Point ( 0 )
u=(theta/180.0f*3.142f); // Calculate Angle Of First Point ( 0 )
x=float(cos(u)*(2.0f+cos(v) ))*r; // Calculate x Position (1st Point)
y=float(sin(u)*(2.0f+cos(v) ))*r; // Calculate y Position (1st Point)
z=float((( u-(2.0f*3.142f)) + sin(v) ) * r); // Calculate z Position (1st Point)
vertexes[0][0]=x; // Set x Value Of First Vertex
vertexes[0][1]=y; // Set y Value Of First Vertex
vertexes[0][2]=z; // Set z Value Of First Vertex
v=(phi/180.0f*3.142f); // Calculate Angle Of Second Point ( 0 )
u=((theta+20)/180.0f*3.142f); // Calculate Angle Of Second Point ( 20 )
x=float(cos(u)*(2.0f+cos(v) ))*r; // Calculate x Position (2nd Point)
y=float(sin(u)*(2.0f+cos(v) ))*r; // Calculate y Position (2nd Point)
z=float((( u-(2.0f*3.142f)) + sin(v) ) * r); // Calculate z Position (2nd Point)
vertexes[1][0]=x; // Set x Value Of Second Vertex
vertexes[1][1]=y; // Set y Value Of Second Vertex
vertexes[1][2]=z; // Set z Value Of Second Vertex
v=((phi+20)/180.0f*3.142f); // Calculate Angle Of Third Point ( 20 )
u=((theta+20)/180.0f*3.142f); // Calculate Angle Of Third Point ( 20 )
x=float(cos(u)*(2.0f+cos(v) ))*r; // Calculate x Position (3rd Point)
y=float(sin(u)*(2.0f+cos(v) ))*r; // Calculate y Position (3rd Point)
z=float((( u-(2.0f*3.142f)) + sin(v) ) * r); // Calculate z Position (3rd Point)
vertexes[2][0]=x; // Set x Value Of Third Vertex
vertexes[2][1]=y; // Set y Value Of Third Vertex
vertexes[2][2]=z; // Set z Value Of Third Vertex
v=((phi+20)/180.0f*3.142f); // Calculate Angle Of Fourth Point ( 20 )
u=((theta)/180.0f*3.142f); // Calculate Angle Of Fourth Point ( 0 )
x=float(cos(u)*(2.0f+cos(v) ))*r; // Calculate x Position (4th Point)
y=float(sin(u)*(2.0f+cos(v) ))*r; // Calculate y Position (4th Point)
z=float((( u-(2.0f*3.142f)) + sin(v) ) * r); // Calculate z Position (4th Point)
vertexes[3][0]=x; // Set x Value Of Fourth Vertex
vertexes[3][1]=y; // Set y Value Of Fourth Vertex
vertexes[3][2]=z; // Set z Value Of Fourth Vertex
calcNormal(vertexes,normal); // Calculate The Quad Normal
glNormal3f(normal[0],normal[1],normal[2]); // Set The Normal
// Render The Quad
glVertex3f(vertexes[0][0],vertexes[0][1],vertexes[0][2]);
glVertex3f(vertexes[1][0],vertexes[1][1],vertexes[1][2]);
glVertex3f(vertexes[2][0],vertexes[2][1],vertexes[2][2]);
glVertex3f(vertexes[3][0],vertexes[3][1],vertexes[3][2]);
}
}
glEnd(); // Done Rendering Quads
glPopMatrix(); // Pop The Matrix
}
void ViewOrtho() // Set Up An Ortho View
{
glMatrixMode(GL_PROJECTION); // Select Projection
glPushMatrix(); // Push The Matrix
glLoadIdentity(); // Reset The Matrix
glOrtho( 0, 640 , 480 , 0, -1, 1 ); // Select Ortho Mode (640x480)
glMatrixMode(GL_MODELVIEW); // Select Modelview Matrix
glPushMatrix(); // Push The Matrix
glLoadIdentity(); // Reset The Matrix
}
void ViewPerspective() // Set Up A Perspective View
{
glMatrixMode( GL_PROJECTION ); // Select Projection
glPopMatrix(); // Pop The Matrix
glMatrixMode( GL_MODELVIEW ); // Select Modelview
glPopMatrix(); // Pop The Matrix
}
void RenderToTexture() // Renders To A Texture
{
glViewport(0,0,128,128); // Set Our Viewport (Match Texture Size)
ProcessHelix(); // Render The Helix
glBindTexture(GL_TEXTURE_2D,BlurTexture); // Bind To The Blur Texture
// Copy Our ViewPort To The Blur Texture (From 0,0 To 128,128... No Border)
glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 0, 0, 128, 128, 0);
glClearColor(0.0f, 0.0f, 0.5f, 0.5); // Set The Clear Color To Medium Blue
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And Depth Buffer
glViewport(0 , 0,640 ,480); // Set Viewport (0,0 to 640x480)
}
void DrawBlur(int times, float inc) // Draw The Blurred Image
{
float spost = 0.0f; // Starting Texture Coordinate Offset
float alphainc = 0.9f / times; // Fade Speed For Alpha Blending
float alpha = 0.2f; // Starting Alpha Value
// Disable AutoTexture Coordinates
glDisable(GL_TEXTURE_GEN_S);
glDisable(GL_TEXTURE_GEN_T);
glEnable(GL_TEXTURE_2D); // Enable 2D Texture Mapping
glDisable(GL_DEPTH_TEST); // Disable Depth Testing
glBlendFunc(GL_SRC_ALPHA,GL_ONE); // Set Blending Mode
glEnable(GL_BLEND); // Enable Blending
glBindTexture(GL_TEXTURE_2D,BlurTexture); // Bind To The Blur Texture
ViewOrtho(); // Switch To An Ortho View
alphainc = alpha / times; // alphainc=0.2f / Times To Render Blur
glBegin(GL_QUADS); // Begin Drawing Quads
for (int num = 0;num < times;num++) // Number Of Times To Render Blur
{
glColor4f(1.0f, 1.0f, 1.0f, alpha); // Set The Alpha Value (Starts At 0.2)
glTexCoord2f(0+spost,1-spost); // Texture Coordinate ( 0, 1 )
glVertex2f(0,0); // First Vertex ( 0, 0 )
glTexCoord2f(0+spost,0+spost); // Texture Coordinate ( 0, 0 )
glVertex2f(0,480); // Second Vertex ( 0, 480 )
glTexCoord2f(1-spost,0+spost); // Texture Coordinate ( 1, 0 )
glVertex2f(640,480); // Third Vertex ( 640, 480 )
glTexCoord2f(1-spost,1-spost); // Texture Coordinate ( 1, 1 )
glVertex2f(640,0); // Fourth Vertex ( 640, 0 )
spost += inc; // Gradually Increase spost (Zooming Closer To Texture Center)
alpha = alpha - alphainc; // Gradually Decrease alpha (Gradually Fading Image Out)
}
glEnd(); // Done Drawing Quads
ViewPerspective(); // Switch To A Perspective View
glEnable(GL_DEPTH_TEST); // Enable Depth Testing
glDisable(GL_TEXTURE_2D); // Disable 2D Texture Mapping
glDisable(GL_BLEND); // Disable Blending
glBindTexture(GL_TEXTURE_2D,0); // Unbind The Blur Texture
}
BOOL Initialize (GL_Window* window, Keys* keys) // Any GL Init Code & User Initialiazation Goes Here
{
g_window = window;
g_keys = keys;
// Start Of User Initialization
angle = 0.0f; // Set Starting Angle To Zero
BlurTexture = EmptyTexture(); // Create Our Empty Texture
glViewport(0 , 0,window->init.width ,window->init.height); // Set Up A Viewport
glMatrixMode(GL_PROJECTION); // Select The Projection Matrix
glLoadIdentity(); // Reset The Projection Matrix
gluPerspective(50, (float)window->init.width/(float)window->init.height, 5, 2000); // Set Our Perspective
glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
glLoadIdentity(); // Reset The Modelview Matrix
glEnable(GL_DEPTH_TEST); // Enable Depth Testing
GLfloat global_ambient[4]={0.2f, 0.2f, 0.2f, 1.0f}; // Set Ambient Lighting To Fairly Dark Light (No Color)
GLfloat light0pos[4]= {0.0f, 5.0f, 10.0f, 1.0f}; // Set The Light Position
GLfloat light0ambient[4]= {0.2f, 0.2f, 0.2f, 1.0f}; // More Ambient Light
GLfloat light0diffuse[4]= {0.3f, 0.3f, 0.3f, 1.0f}; // Set The Diffuse Light A Bit Brighter
GLfloat light0specular[4]={0.8f, 0.8f, 0.8f, 1.0f}; // Fairly Bright Specular Lighting
GLfloat lmodel_ambient[]= {0.2f,0.2f,0.2f,1.0f}; // And More Ambient Light
glLightModelfv(GL_LIGHT_MODEL_AMBIENT,lmodel_ambient); // Set The Ambient Light Model
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, global_ambient); // Set The Global Ambient Light Model
glLightfv(GL_LIGHT0, GL_POSITION, light0pos); // Set The Lights Position
glLightfv(GL_LIGHT0, GL_AMBIENT, light0ambient); // Set The Ambient Light
glLightfv(GL_LIGHT0, GL_DIFFUSE, light0diffuse); // Set The Diffuse Light
glLightfv(GL_LIGHT0, GL_SPECULAR, light0specular); // Set Up Specular Lighting
glEnable(GL_LIGHTING); // Enable Lighting
glEnable(GL_LIGHT0); // Enable Light0
glShadeModel(GL_SMOOTH); // Select Smooth Shading
glMateriali(GL_FRONT, GL_SHININESS, 128);
glClearColor(0.0f, 0.0f, 0.0f, 0.5); // Set The Clear Color To Black
return TRUE; // Return TRUE (Initialization Successful)
}
void Deinitialize (void) // Any User DeInitialization Goes Here
{
glDeleteTextures(1,&BlurTexture); // Delete The Blur Texture
}
void Update (DWORD milliseconds) // Perform Motion Updates Here
{
if (g_keys->keyDown [VK_ESCAPE] == TRUE) // Is ESC Being Pressed?
{
TerminateApplication (g_window); // Terminate The Program
}
if (g_keys->keyDown [VK_F1] == TRUE) // Is F1 Being Pressed?
{
ToggleFullscreen (g_window); // Toggle Fullscreen Mode
}
angle += (float)(milliseconds) / 5.0f; // Update angle Based On The Clock
}
void Draw (void) // Draw The Scene
{
glClearColor(0.0f, 0.0f, 0.0f, 0.5); // Set The Clear Color To Black
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glLoadIdentity(); // Reset The View
RenderToTexture(); // Render To A Texture
ProcessHelix(); // Draw Our Helix
DrawBlur(25,0.02f); // Draw The Blur Effect
glFlush (); // Flush The GL Rendering Pipeline
}