glfw/examples/boing.c
Camilla Löwy d7e30b1c74 Replace glad and the Vulkan SDK with glad2
This removes all dependencies from the GLFW test programs on the Vulkan
SDK.

It also removes support for linking the GLFW shared library (dynamic
library, DLL) against the Vulkan loader static library.
2019-04-15 02:45:48 +02:00

679 lines
19 KiB
C

/*****************************************************************************
* Title: GLBoing
* Desc: Tribute to Amiga Boing.
* Author: Jim Brooks <gfx@jimbrooks.org>
* Original Amiga authors were R.J. Mical and Dale Luck.
* GLFW conversion by Marcus Geelnard
* Notes: - 360' = 2*PI [radian]
*
* - Distances between objects are created by doing a relative
* Z translations.
*
* - Although OpenGL enticingly supports alpha-blending,
* the shadow of the original Boing didn't affect the color
* of the grid.
*
* - [Marcus] Changed timing scheme from interval driven to frame-
* time based animation steps (which results in much smoother
* movement)
*
* History of Amiga Boing:
*
* Boing was demonstrated on the prototype Amiga (codenamed "Lorraine") in
* 1985. According to legend, it was written ad-hoc in one night by
* R. J. Mical and Dale Luck. Because the bouncing ball animation was so fast
* and smooth, attendees did not believe the Amiga prototype was really doing
* the rendering. Suspecting a trick, they began looking around the booth for
* a hidden computer or VCR.
*****************************************************************************/
#if defined(_MSC_VER)
// Make MS math.h define M_PI
#define _USE_MATH_DEFINES
#endif
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <glad/gl.h>
#include <GLFW/glfw3.h>
#include <linmath.h>
/*****************************************************************************
* Various declarations and macros
*****************************************************************************/
/* Prototypes */
void init( void );
void display( void );
void reshape( GLFWwindow* window, int w, int h );
void key_callback( GLFWwindow* window, int key, int scancode, int action, int mods );
void mouse_button_callback( GLFWwindow* window, int button, int action, int mods );
void cursor_position_callback( GLFWwindow* window, double x, double y );
void DrawBoingBall( void );
void BounceBall( double dt );
void DrawBoingBallBand( GLfloat long_lo, GLfloat long_hi );
void DrawGrid( void );
#define RADIUS 70.f
#define STEP_LONGITUDE 22.5f /* 22.5 makes 8 bands like original Boing */
#define STEP_LATITUDE 22.5f
#define DIST_BALL (RADIUS * 2.f + RADIUS * 0.1f)
#define VIEW_SCENE_DIST (DIST_BALL * 3.f + 200.f)/* distance from viewer to middle of boing area */
#define GRID_SIZE (RADIUS * 4.5f) /* length (width) of grid */
#define BOUNCE_HEIGHT (RADIUS * 2.1f)
#define BOUNCE_WIDTH (RADIUS * 2.1f)
#define SHADOW_OFFSET_X -20.f
#define SHADOW_OFFSET_Y 10.f
#define SHADOW_OFFSET_Z 0.f
#define WALL_L_OFFSET 0.f
#define WALL_R_OFFSET 5.f
/* Animation speed (50.0 mimics the original GLUT demo speed) */
#define ANIMATION_SPEED 50.f
/* Maximum allowed delta time per physics iteration */
#define MAX_DELTA_T 0.02f
/* Draw ball, or its shadow */
typedef enum { DRAW_BALL, DRAW_BALL_SHADOW } DRAW_BALL_ENUM;
/* Vertex type */
typedef struct {float x; float y; float z;} vertex_t;
/* Global vars */
int windowed_xpos, windowed_ypos, windowed_width, windowed_height;
int width, height;
GLfloat deg_rot_y = 0.f;
GLfloat deg_rot_y_inc = 2.f;
int override_pos = GLFW_FALSE;
GLfloat cursor_x = 0.f;
GLfloat cursor_y = 0.f;
GLfloat ball_x = -RADIUS;
GLfloat ball_y = -RADIUS;
GLfloat ball_x_inc = 1.f;
GLfloat ball_y_inc = 2.f;
DRAW_BALL_ENUM drawBallHow;
double t;
double t_old = 0.f;
double dt;
/* Random number generator */
#ifndef RAND_MAX
#define RAND_MAX 4095
#endif
/*****************************************************************************
* Truncate a degree.
*****************************************************************************/
GLfloat TruncateDeg( GLfloat deg )
{
if ( deg >= 360.f )
return (deg - 360.f);
else
return deg;
}
/*****************************************************************************
* Convert a degree (360-based) into a radian.
* 360' = 2 * PI
*****************************************************************************/
double deg2rad( double deg )
{
return deg / 360 * (2 * M_PI);
}
/*****************************************************************************
* 360' sin().
*****************************************************************************/
double sin_deg( double deg )
{
return sin( deg2rad( deg ) );
}
/*****************************************************************************
* 360' cos().
*****************************************************************************/
double cos_deg( double deg )
{
return cos( deg2rad( deg ) );
}
/*****************************************************************************
* Compute a cross product (for a normal vector).
*
* c = a x b
*****************************************************************************/
void CrossProduct( vertex_t a, vertex_t b, vertex_t c, vertex_t *n )
{
GLfloat u1, u2, u3;
GLfloat v1, v2, v3;
u1 = b.x - a.x;
u2 = b.y - a.y;
u3 = b.y - a.z;
v1 = c.x - a.x;
v2 = c.y - a.y;
v3 = c.z - a.z;
n->x = u2 * v3 - v2 * u3;
n->y = u3 * v1 - v3 * u1;
n->z = u1 * v2 - v1 * u2;
}
#define BOING_DEBUG 0
/*****************************************************************************
* init()
*****************************************************************************/
void init( void )
{
/*
* Clear background.
*/
glClearColor( 0.55f, 0.55f, 0.55f, 0.f );
glShadeModel( GL_FLAT );
}
/*****************************************************************************
* display()
*****************************************************************************/
void display(void)
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glPushMatrix();
drawBallHow = DRAW_BALL_SHADOW;
DrawBoingBall();
DrawGrid();
drawBallHow = DRAW_BALL;
DrawBoingBall();
glPopMatrix();
glFlush();
}
/*****************************************************************************
* reshape()
*****************************************************************************/
void reshape( GLFWwindow* window, int w, int h )
{
mat4x4 projection, view;
glViewport( 0, 0, (GLsizei)w, (GLsizei)h );
glMatrixMode( GL_PROJECTION );
mat4x4_perspective( projection,
2.f * (float) atan2( RADIUS, 200.f ),
(float)w / (float)h,
1.f, VIEW_SCENE_DIST );
glLoadMatrixf((const GLfloat*) projection);
glMatrixMode( GL_MODELVIEW );
{
vec3 eye = { 0.f, 0.f, VIEW_SCENE_DIST };
vec3 center = { 0.f, 0.f, 0.f };
vec3 up = { 0.f, -1.f, 0.f };
mat4x4_look_at( view, eye, center, up );
}
glLoadMatrixf((const GLfloat*) view);
}
void key_callback( GLFWwindow* window, int key, int scancode, int action, int mods )
{
if (action != GLFW_PRESS)
return;
if (key == GLFW_KEY_ESCAPE && mods == 0)
glfwSetWindowShouldClose(window, GLFW_TRUE);
if ((key == GLFW_KEY_ENTER && mods == GLFW_MOD_ALT) ||
(key == GLFW_KEY_F11 && mods == GLFW_MOD_ALT))
{
if (glfwGetWindowMonitor(window))
{
glfwSetWindowMonitor(window, NULL,
windowed_xpos, windowed_ypos,
windowed_width, windowed_height, 0);
}
else
{
GLFWmonitor* monitor = glfwGetPrimaryMonitor();
if (monitor)
{
const GLFWvidmode* mode = glfwGetVideoMode(monitor);
glfwGetWindowPos(window, &windowed_xpos, &windowed_ypos);
glfwGetWindowSize(window, &windowed_width, &windowed_height);
glfwSetWindowMonitor(window, monitor, 0, 0, mode->width, mode->height, mode->refreshRate);
}
}
}
}
static void set_ball_pos ( GLfloat x, GLfloat y )
{
ball_x = (width / 2) - x;
ball_y = y - (height / 2);
}
void mouse_button_callback( GLFWwindow* window, int button, int action, int mods )
{
if (button != GLFW_MOUSE_BUTTON_LEFT)
return;
if (action == GLFW_PRESS)
{
override_pos = GLFW_TRUE;
set_ball_pos(cursor_x, cursor_y);
}
else
{
override_pos = GLFW_FALSE;
}
}
void cursor_position_callback( GLFWwindow* window, double x, double y )
{
cursor_x = (float) x;
cursor_y = (float) y;
if ( override_pos )
set_ball_pos(cursor_x, cursor_y);
}
/*****************************************************************************
* Draw the Boing ball.
*
* The Boing ball is sphere in which each facet is a rectangle.
* Facet colors alternate between red and white.
* The ball is built by stacking latitudinal circles. Each circle is composed
* of a widely-separated set of points, so that each facet is noticeably large.
*****************************************************************************/
void DrawBoingBall( void )
{
GLfloat lon_deg; /* degree of longitude */
double dt_total, dt2;
glPushMatrix();
glMatrixMode( GL_MODELVIEW );
/*
* Another relative Z translation to separate objects.
*/
glTranslatef( 0.0, 0.0, DIST_BALL );
/* Update ball position and rotation (iterate if necessary) */
dt_total = dt;
while( dt_total > 0.0 )
{
dt2 = dt_total > MAX_DELTA_T ? MAX_DELTA_T : dt_total;
dt_total -= dt2;
BounceBall( dt2 );
deg_rot_y = TruncateDeg( deg_rot_y + deg_rot_y_inc*((float)dt2*ANIMATION_SPEED) );
}
/* Set ball position */
glTranslatef( ball_x, ball_y, 0.0 );
/*
* Offset the shadow.
*/
if ( drawBallHow == DRAW_BALL_SHADOW )
{
glTranslatef( SHADOW_OFFSET_X,
SHADOW_OFFSET_Y,
SHADOW_OFFSET_Z );
}
/*
* Tilt the ball.
*/
glRotatef( -20.0, 0.0, 0.0, 1.0 );
/*
* Continually rotate ball around Y axis.
*/
glRotatef( deg_rot_y, 0.0, 1.0, 0.0 );
/*
* Set OpenGL state for Boing ball.
*/
glCullFace( GL_FRONT );
glEnable( GL_CULL_FACE );
glEnable( GL_NORMALIZE );
/*
* Build a faceted latitude slice of the Boing ball,
* stepping same-sized vertical bands of the sphere.
*/
for ( lon_deg = 0;
lon_deg < 180;
lon_deg += STEP_LONGITUDE )
{
/*
* Draw a latitude circle at this longitude.
*/
DrawBoingBallBand( lon_deg,
lon_deg + STEP_LONGITUDE );
}
glPopMatrix();
return;
}
/*****************************************************************************
* Bounce the ball.
*****************************************************************************/
void BounceBall( double delta_t )
{
GLfloat sign;
GLfloat deg;
if ( override_pos )
return;
/* Bounce on walls */
if ( ball_x > (BOUNCE_WIDTH/2 + WALL_R_OFFSET ) )
{
ball_x_inc = -0.5f - 0.75f * (GLfloat)rand() / (GLfloat)RAND_MAX;
deg_rot_y_inc = -deg_rot_y_inc;
}
if ( ball_x < -(BOUNCE_HEIGHT/2 + WALL_L_OFFSET) )
{
ball_x_inc = 0.5f + 0.75f * (GLfloat)rand() / (GLfloat)RAND_MAX;
deg_rot_y_inc = -deg_rot_y_inc;
}
/* Bounce on floor / roof */
if ( ball_y > BOUNCE_HEIGHT/2 )
{
ball_y_inc = -0.75f - 1.f * (GLfloat)rand() / (GLfloat)RAND_MAX;
}
if ( ball_y < -BOUNCE_HEIGHT/2*0.85 )
{
ball_y_inc = 0.75f + 1.f * (GLfloat)rand() / (GLfloat)RAND_MAX;
}
/* Update ball position */
ball_x += ball_x_inc * ((float)delta_t*ANIMATION_SPEED);
ball_y += ball_y_inc * ((float)delta_t*ANIMATION_SPEED);
/*
* Simulate the effects of gravity on Y movement.
*/
if ( ball_y_inc < 0 ) sign = -1.0; else sign = 1.0;
deg = (ball_y + BOUNCE_HEIGHT/2) * 90 / BOUNCE_HEIGHT;
if ( deg > 80 ) deg = 80;
if ( deg < 10 ) deg = 10;
ball_y_inc = sign * 4.f * (float) sin_deg( deg );
}
/*****************************************************************************
* Draw a faceted latitude band of the Boing ball.
*
* Parms: long_lo, long_hi
* Low and high longitudes of slice, resp.
*****************************************************************************/
void DrawBoingBallBand( GLfloat long_lo,
GLfloat long_hi )
{
vertex_t vert_ne; /* "ne" means south-east, so on */
vertex_t vert_nw;
vertex_t vert_sw;
vertex_t vert_se;
vertex_t vert_norm;
GLfloat lat_deg;
static int colorToggle = 0;
/*
* Iterate through the points of a latitude circle.
* A latitude circle is a 2D set of X,Z points.
*/
for ( lat_deg = 0;
lat_deg <= (360 - STEP_LATITUDE);
lat_deg += STEP_LATITUDE )
{
/*
* Color this polygon with red or white.
*/
if ( colorToggle )
glColor3f( 0.8f, 0.1f, 0.1f );
else
glColor3f( 0.95f, 0.95f, 0.95f );
#if 0
if ( lat_deg >= 180 )
if ( colorToggle )
glColor3f( 0.1f, 0.8f, 0.1f );
else
glColor3f( 0.5f, 0.5f, 0.95f );
#endif
colorToggle = ! colorToggle;
/*
* Change color if drawing shadow.
*/
if ( drawBallHow == DRAW_BALL_SHADOW )
glColor3f( 0.35f, 0.35f, 0.35f );
/*
* Assign each Y.
*/
vert_ne.y = vert_nw.y = (float) cos_deg(long_hi) * RADIUS;
vert_sw.y = vert_se.y = (float) cos_deg(long_lo) * RADIUS;
/*
* Assign each X,Z with sin,cos values scaled by latitude radius indexed by longitude.
* Eg, long=0 and long=180 are at the poles, so zero scale is sin(longitude),
* while long=90 (sin(90)=1) is at equator.
*/
vert_ne.x = (float) cos_deg( lat_deg ) * (RADIUS * (float) sin_deg( long_lo + STEP_LONGITUDE ));
vert_se.x = (float) cos_deg( lat_deg ) * (RADIUS * (float) sin_deg( long_lo ));
vert_nw.x = (float) cos_deg( lat_deg + STEP_LATITUDE ) * (RADIUS * (float) sin_deg( long_lo + STEP_LONGITUDE ));
vert_sw.x = (float) cos_deg( lat_deg + STEP_LATITUDE ) * (RADIUS * (float) sin_deg( long_lo ));
vert_ne.z = (float) sin_deg( lat_deg ) * (RADIUS * (float) sin_deg( long_lo + STEP_LONGITUDE ));
vert_se.z = (float) sin_deg( lat_deg ) * (RADIUS * (float) sin_deg( long_lo ));
vert_nw.z = (float) sin_deg( lat_deg + STEP_LATITUDE ) * (RADIUS * (float) sin_deg( long_lo + STEP_LONGITUDE ));
vert_sw.z = (float) sin_deg( lat_deg + STEP_LATITUDE ) * (RADIUS * (float) sin_deg( long_lo ));
/*
* Draw the facet.
*/
glBegin( GL_POLYGON );
CrossProduct( vert_ne, vert_nw, vert_sw, &vert_norm );
glNormal3f( vert_norm.x, vert_norm.y, vert_norm.z );
glVertex3f( vert_ne.x, vert_ne.y, vert_ne.z );
glVertex3f( vert_nw.x, vert_nw.y, vert_nw.z );
glVertex3f( vert_sw.x, vert_sw.y, vert_sw.z );
glVertex3f( vert_se.x, vert_se.y, vert_se.z );
glEnd();
#if BOING_DEBUG
printf( "----------------------------------------------------------- \n" );
printf( "lat = %f long_lo = %f long_hi = %f \n", lat_deg, long_lo, long_hi );
printf( "vert_ne x = %.8f y = %.8f z = %.8f \n", vert_ne.x, vert_ne.y, vert_ne.z );
printf( "vert_nw x = %.8f y = %.8f z = %.8f \n", vert_nw.x, vert_nw.y, vert_nw.z );
printf( "vert_se x = %.8f y = %.8f z = %.8f \n", vert_se.x, vert_se.y, vert_se.z );
printf( "vert_sw x = %.8f y = %.8f z = %.8f \n", vert_sw.x, vert_sw.y, vert_sw.z );
#endif
}
/*
* Toggle color so that next band will opposite red/white colors than this one.
*/
colorToggle = ! colorToggle;
/*
* This circular band is done.
*/
return;
}
/*****************************************************************************
* Draw the purple grid of lines, behind the Boing ball.
* When the Workbench is dropped to the bottom, Boing shows 12 rows.
*****************************************************************************/
void DrawGrid( void )
{
int row, col;
const int rowTotal = 12; /* must be divisible by 2 */
const int colTotal = rowTotal; /* must be same as rowTotal */
const GLfloat widthLine = 2.0; /* should be divisible by 2 */
const GLfloat sizeCell = GRID_SIZE / rowTotal;
const GLfloat z_offset = -40.0;
GLfloat xl, xr;
GLfloat yt, yb;
glPushMatrix();
glDisable( GL_CULL_FACE );
/*
* Another relative Z translation to separate objects.
*/
glTranslatef( 0.0, 0.0, DIST_BALL );
/*
* Draw vertical lines (as skinny 3D rectangles).
*/
for ( col = 0; col <= colTotal; col++ )
{
/*
* Compute co-ords of line.
*/
xl = -GRID_SIZE / 2 + col * sizeCell;
xr = xl + widthLine;
yt = GRID_SIZE / 2;
yb = -GRID_SIZE / 2 - widthLine;
glBegin( GL_POLYGON );
glColor3f( 0.6f, 0.1f, 0.6f ); /* purple */
glVertex3f( xr, yt, z_offset ); /* NE */
glVertex3f( xl, yt, z_offset ); /* NW */
glVertex3f( xl, yb, z_offset ); /* SW */
glVertex3f( xr, yb, z_offset ); /* SE */
glEnd();
}
/*
* Draw horizontal lines (as skinny 3D rectangles).
*/
for ( row = 0; row <= rowTotal; row++ )
{
/*
* Compute co-ords of line.
*/
yt = GRID_SIZE / 2 - row * sizeCell;
yb = yt - widthLine;
xl = -GRID_SIZE / 2;
xr = GRID_SIZE / 2 + widthLine;
glBegin( GL_POLYGON );
glColor3f( 0.6f, 0.1f, 0.6f ); /* purple */
glVertex3f( xr, yt, z_offset ); /* NE */
glVertex3f( xl, yt, z_offset ); /* NW */
glVertex3f( xl, yb, z_offset ); /* SW */
glVertex3f( xr, yb, z_offset ); /* SE */
glEnd();
}
glPopMatrix();
return;
}
/*======================================================================*
* main()
*======================================================================*/
int main( void )
{
GLFWwindow* window;
/* Init GLFW */
if( !glfwInit() )
exit( EXIT_FAILURE );
window = glfwCreateWindow( 400, 400, "Boing (classic Amiga demo)", NULL, NULL );
if (!window)
{
glfwTerminate();
exit( EXIT_FAILURE );
}
glfwSetWindowAspectRatio(window, 1, 1);
glfwSetFramebufferSizeCallback(window, reshape);
glfwSetKeyCallback(window, key_callback);
glfwSetMouseButtonCallback(window, mouse_button_callback);
glfwSetCursorPosCallback(window, cursor_position_callback);
glfwMakeContextCurrent(window);
gladLoadGL(glfwGetProcAddress);
glfwSwapInterval( 1 );
glfwGetFramebufferSize(window, &width, &height);
reshape(window, width, height);
glfwSetTime( 0.0 );
init();
/* Main loop */
for (;;)
{
/* Timing */
t = glfwGetTime();
dt = t - t_old;
t_old = t;
/* Draw one frame */
display();
/* Swap buffers */
glfwSwapBuffers(window);
glfwPollEvents();
/* Check if we are still running */
if (glfwWindowShouldClose(window))
break;
}
glfwTerminate();
exit( EXIT_SUCCESS );
}