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examples/boing: Add ball-follow-cursor functionality

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Make it so that in the boing example, when the user clicks, the ball
follows the mouse cursor.
This commit is contained in:
Jonas Ådahl 2014-06-29 16:51:25 +02:00
parent 7d373477ed
commit 819e148510
1 changed files with 42 additions and 1 deletions
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43
examples/boing.c
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@ -44,6 +44,8 @@ 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 );
@ -80,8 +82,12 @@ typedef enum { DRAW_BALL, DRAW_BALL_SHADOW } DRAW_BALL_ENUM;
typedef struct {float x; float y; float z;} vertex_t;
/* Global vars */
int width, height;
GLfloat deg_rot_y = 0.f;
GLfloat deg_rot_y_inc = 2.f;
GLboolean override_pos = GL_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;
@ -251,6 +257,37 @@ void key_callback( GLFWwindow* window, int key, int scancode, int action, int mo
glfwSetWindowShouldClose(window, GL_TRUE);
}
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 = GL_TRUE;
set_ball_pos(cursor_x, cursor_y);
}
else
{
override_pos = GL_FALSE;
}
}
void cursor_position_callback( GLFWwindow* window, double x, double y )
{
cursor_x = x;
cursor_y = y;
if ( override_pos )
set_ball_pos(cursor_x, cursor_y);
}
/*****************************************************************************
* Draw the Boing ball.
*
@ -341,6 +378,9 @@ 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 ) )
{
@ -574,7 +614,6 @@ void DrawGrid( void )
int main( void )
{
GLFWwindow* window;
int width, height;
/* Init GLFW */
if( !glfwInit() )
@ -591,6 +630,8 @@ int main( void )
glfwSetFramebufferSizeCallback(window, reshape);
glfwSetKeyCallback(window, key_callback);
glfwSetMouseButtonCallback(window, mouse_button_callback);
glfwSetCursorPosCallback(window, cursor_position_callback);
glfwMakeContextCurrent(window);
glfwSwapInterval( 1 );