Break Some Bricks
We add collision detection to the bricks and break the brick when it gets hit
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The last brickout tutorial in this series. We break a few bricks. There some major things missing like being able to lose, or start over. But a gameover screen would require us to use textures (which we will get into in Invaders).
main.c
#include <epoxy/gl.h>
#include <epoxy/glx.h>
#include <gtk/gtk.h>
#include <math.h>
#include "DashGL/dashgl.h"
#define WIDTH 640.0f
#define HEIGHT 480.0f
static void on_realize(GtkGLArea *area);
static void on_render(GtkGLArea *area, GdkGLContext *context);
static gboolean on_idle(gpointer data);
static gboolean on_keydown(GtkWidget *widget, GdkEventKey *event);
static gboolean on_keyup(GtkWidget *widget, GdkEventKey *event);
struct {
float dx, dy;
float r;
vec3 pos;
vec3 color;
mat4 mvp;
GLuint vbo;
gboolean left, right, top, bottom;
} ball;
struct {
float width;
float height;
float dx;
vec3 pos;
vec3 color;
mat4 mvp;
GLuint vbo;
gboolean key_left;
gboolean key_right;
} paddle;
struct bricks {
float width;
float height;
mat4 mvp[36];
vec3 pos[36];
gboolean on[36];
vec3 color[6];
GLuint vbo;
} bricks;
GLuint program;
GLuint vao;
GLint attribute_coord2d;
GLint uniform_mvp, uniform_color;
int main(int argc, char *argv[]) {
GtkWidget *window;
GtkWidget *glArea;
gtk_init(&argc, &argv);
// Initialize Window
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_title(GTK_WINDOW(window), "Brickout Tutorial");
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
gtk_window_set_default_size(GTK_WINDOW(window), 640, 480);
gtk_window_set_type_hint(GTK_WINDOW(window), GDK_WINDOW_TYPE_HINT_UTILITY);
g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
g_signal_connect(window, "key-press-event", G_CALLBACK(on_keydown), NULL);
g_signal_connect(window, "key-release-event", G_CALLBACK(on_keyup), NULL);
// Initialize GTK GL Area
glArea = gtk_gl_area_new();
gtk_widget_set_vexpand(glArea, TRUE);
gtk_widget_set_hexpand(glArea, TRUE);
g_signal_connect(glArea, "realize", G_CALLBACK(on_realize), NULL);
g_signal_connect(glArea, "render", G_CALLBACK(on_render), NULL);
gtk_container_add(GTK_CONTAINER(window), glArea);
// Show widgets
gtk_widget_show_all(window);
gtk_main();
return 0;
}
static void on_realize(GtkGLArea *area) {
// Debug Message
g_print("on realize\n");
gtk_gl_area_make_current(area);
if(gtk_gl_area_get_error(area) != NULL) {
fprintf(stderr, "Unknown error\n");
return;
}
const GLubyte *renderer = glGetString(GL_RENDER);
const GLubyte *version = glGetString(GL_VERSION);
const GLubyte *shader = glGetString(GL_SHADING_LANGUAGE_VERSION);
printf("Shader %s\n", shader);
printf("Renderer: %s\n", renderer);
printf("OpenGL version supported %s\n", version);
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
ball.r = 18.0f;
int i;
float angle, nextAngle;
int num_segments = 99;
GLfloat circle_vertices[6 * 100];
for(i = 0; i bricks.on[i] = TRUE;
mat4_translate(bricks.pos[i], bricks.mvp[i]);
}
}
}
static void on_render(GtkGLArea *area, GdkGLContext *context) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
mat4_translate(ball.pos, ball.mvp);
glUniformMatrix4fv(uniform_mvp, 1, GL_FALSE, ball.mvp);
glUniform3fv(uniform_color, 1, ball.color);
glBindVertexArray(vao);
glEnableVertexAttribArray(attribute_coord2d);
glBindBuffer(GL_ARRAY_BUFFER, ball.vbo);
glVertexAttribPointer(
attribute_coord2d,
2,
GL_FLOAT,
GL_FALSE,
0,
0
);
glDrawArrays(GL_TRIANGLES, 0, 3 * 100);
mat4_translate(paddle.pos, paddle.mvp);
glUniformMatrix4fv(uniform_mvp, 1, GL_FALSE, paddle.mvp);
glUniform3fv(uniform_color, 1, paddle.color);
glBindBuffer(GL_ARRAY_BUFFER, paddle.vbo);
glVertexAttribPointer(
attribute_coord2d,
2,
GL_FLOAT,
GL_FALSE,
0,
0
);
glDrawArrays(GL_TRIANGLES, 0, 3 * 2);
glBindBuffer(GL_ARRAY_BUFFER, bricks.vbo);
glVertexAttribPointer(
attribute_coord2d,
2,
GL_FLOAT,
GL_FALSE,
0,
0
);
int i, x, y;
for(y = 0; y <6; y++) {
glUniform3fv(uniform_color, 1, bricks.color[y]);
for(x = 0; x <6; x++) {
i = y* 6 + x;
if(!bricks.on[i]) {
continue;
}
glUniformMatrix4fv(uniform_mvp, 1, GL_FALSE, bricks.mvp[i]);
glDrawArrays(GL_TRIANGLES, 0, 3 * 2);
}
}
glDisableVertexAttribArray(attribute_coord2d);
}
static gboolean on_idle(gpointer data) {
int i;
for(i = 0; i <36; i++) {
if(!bricks.on[i]) {
continue;
}
ball.left = ball.pos[0] - ball.r > bricks.pos[i][0] - bricks.width;
ball.right = ball.pos[0] + ball.r bricks.pos[i][1] - bricks.width;
ball.top = ball.pos[1] + ball.r
ball.pos[0] += ball.dx;
ball.pos[1] += ball.dy;
if(ball.pos[0] > WIDTH) {
ball.pos[0] = WIDTH;
ball.dx *= -1;
} else if(ball.pos[0] <0) {
ball.pos[0] = 0;
ball.dx *= -1;
}
if(ball.pos[1] > HEIGHT) {
ball.pos[1] = HEIGHT;
ball.dy *= -1;
} else if(ball.pos[1] <0) {
ball.pos[1] = 0;
ball.dy *= -1;
}
if(paddle.key_left) {
paddle.pos[0] -= paddle.dx;
}
if(paddle.key_right) {
paddle.pos[0] += paddle.dx;
}
if(paddle.pos[0] <0) {
paddle.pos[0] = 0.0f;
} else if(paddle.pos[0] > WIDTH) {
paddle.pos[0] = WIDTH;
}
ball.left = ball.pos[0] > paddle.pos[0] - paddle.width;
ball.right = ball.pos[0] paddle.pos[1] - paddle.height;
if(ball.dy <0 && ball.left && ball.right && ball.top && ball.bottom) {
ball.dy *= -1.025;
}
gtk_widget_queue_draw(GTK_WIDGET(data));
return TRUE;
}
static gboolean on_keydown(GtkWidget *widget, GdkEventKey *event) {
switch(event->keyval) {
case GDK_KEY_Left:
paddle.key_left = TRUE;
break;
case GDK_KEY_Right:
paddle.key_right = TRUE;
break;
}
}
static gboolean on_keyup(GtkWidget *widget, GdkEventKey *event) {
switch(event->keyval) {
case GDK_KEY_Left:
paddle.key_left = FALSE;
break;
case GDK_KEY_Right:
paddle.key_right = FALSE;
break;
}
}
Compile
$ gcc -c -o DashGL/dashgl.o DashGL/dashgl.c -lepoxy -lpng -lm
$ gcc `pkg-config --cflags gtk+-3.0` main.c DashGL/dashgl.o `pkg-config --libs gtk+-3.0` \
-lepoxy -lm -lpngRun
$ ./a.out