added two jiggle effects and command for toggling them

config.json

@@ -16,7 +16,8 @@
         "print-video-memory-size": ["CTRL", "v"],
         "print-frame-length-history": ["CTRL", "SHIFT", "h"],
         "toggle-camera": ["CTRL", "c"],
-        "toggle-item": ["CTRL", "i"]
+        "toggle-item": ["CTRL", "i"],
+        "effect": ["CTRL", "e"]
     },
     "recording":
     {
@@ -44,7 +45,7 @@
     {
         "json-save": true,
         "json-save-directory": "local/scans",
-        "barcode": "071146005280",
+        "barcode": "",
         "capture-device": "/dev/video0"
     },
     "api":

src/Pudding.cpp

@@ -36,7 +36,6 @@ Pudding::Pudding()
     set_pudding_model(1.0f, 1.6f, 10, 12, -.6, .6, .25);
     /* use gl context so we can draw 3D */
     load_gl_context();
-    initialize_camera();
 }
 
 /* Assign vertices, colors and texture UV coordinates to the pudding model */
@@ -221,7 +220,9 @@ void Pudding::load_gl_context()
     glBindAttribLocation(mvp_program, 3, "in_color");
     glBindAttribLocation(mvp_program, 4, "vertex_uv");
     link_shader(mvp_program);
-    mvp_id = glGetUniformLocation(mvp_program, "mvp");
+    mvp_uniform_location = glGetUniformLocation(mvp_program, "mvp");
+    time_uniform_location = glGetUniformLocation(mvp_program, "time");
+    effect_uniform_location = glGetUniformLocation(mvp_program, "effect");
     log_gl_errors();
 }
 
@@ -287,6 +288,13 @@ void Pudding::respond(SDL_Event& event)
     {
         show_item = !show_item;
     }
+    /* The effect command switches the active effect to the next in the list, wrapping around at the end */
+    else if (get_delegate().compare(event, "effect"))
+    {
+        effect_id = ++effect_id % Effect::COUNT;
+        glUseProgram(mvp_program);
+        glUniform1i(effect_uniform_location, effect_id);
+    }
 }
 
 /* Build an Item object by submitting the upc parameter to multiple APIs and taking
@@ -669,13 +677,14 @@ void Pudding::update()
     glDrawArrays(GL_TRIANGLES, 0, 6);
     /* draw pudding model using MVP shader */
     glUseProgram(mvp_program);
+    glUniform1f(time_uniform_location, SDL_GetTicks() / 1000.0f);
     /* calculate the transformation matrix for displaying pudding in viewport */
     model = glm::rotate(model, weight(get_configuration()["pudding"]["rotation-speed"].get<float>()), Y_UNIT_NORMAL_3D);
     projection = glm::perspective(
         glm::radians(40.0f * 1 / viewport_box.aspect()), viewport_box.aspect(), 0.1f, 100.0f);
     mvp = projection * VIEW_MATRIX * model;
     /* pass the mvp matrix to the shader */
-    glUniformMatrix4fv(mvp_id, 1, GL_FALSE, &mvp[0][0]);
+    glUniformMatrix4fv(mvp_uniform_location, 1, GL_FALSE, &mvp[0][0]);
     /* disable rectangle attributes and enable pudding attributes */
     glDisableVertexAttribArray(0);
     glDisableVertexAttribArray(1);

src/Pudding.hpp

@@ -27,6 +27,16 @@ class Pudding : public Game
 
 private:
 
+    /* Defines for effect IDs that will be passed to the shader program. Since COUNT is last and every value
+     * is the default integer, it will define the number of effects available */
+    enum Effect
+    {
+        NONE,
+        SNAKE,
+        WOBBLE,
+        COUNT
+    };
+
     typedef Game super;
     const std::string OPEN_FOOD_API_URL = "https://world.openfoodfacts.org/api/v0/product/";
     const std::string NUTRONIX_API_URL = "https://trackapi.nutritionix.com/v2/search/item?upc=";
@@ -46,11 +56,13 @@ private:
     cv::VideoCapture capture;
     cv::Mat capture_frame;
     zbar::ImageScanner image_scanner;
-    GLuint flat_program, mvp_program, video_capture_texture_id, mvp_id, background_texture_id;
+    GLuint flat_program, mvp_program, video_capture_texture_id, mvp_uniform_location, background_texture_id, time_uniform_location,
+        effect_uniform_location;
     glm::mat4 projection, model = glm::mat4(1.0f), mvp;
     std::vector<glm::vec3> pudding_vertices, pudding_colors;
     std::vector<glm::vec2> pudding_uv;
     bool show_item;
+    int effect_id = Effect::NONE;
 
     void set_pudding_model(float, float, int, int = 1, float = -1, float = 1, float = 0.3f);
     void load_gl_context();

src/mvp.vert

@@ -1,17 +1,57 @@
 #version 130
 
+#define PI 3.1415926535897932384626433832795
+#define AMPLITUDE 0.2
+#define PERIOD .5
+#define WAVELENGTH 2.5
+#define EFFECT_NONE 0
+#define EFFECT_SNAKE 1
+#define EFFECT_WOBBLE 2
+
 in vec3 in_position;
 in vec3 in_color;
 in vec2 vertex_uv;
 uniform mat4 mvp;
+uniform float time;
+uniform int effect = EFFECT_NONE;
 out vec3 ex_color;
 out float x;
 out vec2 uv;
 
-void main(void)
+/* Offset X-coordinate according to the time step and Y-coordinate to create a wobble effect when run on
+ * flattened coordinates (after projection matrix has been applied) */
+void wobble()
 {
-    gl_Position = mvp * vec4(in_position, 1);
+    gl_Position.x += sin(time * 10.0) * in_position.y / 2.0;
+}    
+
+/* Contort the X-coordinate according the time step and Y-coordinate using the sine function. This contorts
+ * the model into a sine wave along the Y-axis. It also moves the sine wave along the Y-axis using the time
+ * step uniform. The shape can be edited by changing the defintions for amplitude (maximum distance from
+ * Y-axis), wavelength (length in GL model coordinates between peaks), and period (amount of time in
+ * seconds it takes to loop through one wavelength cycle). */
+void snake()
+{
+    gl_Position = vec4(
+        in_position.x + AMPLITUDE * sin(2.0 * PI / PERIOD * (time + in_position.y * PERIOD / WAVELENGTH)), in_position.yz, 1);
+}
+
+void main()
+{
+    if (effect == EFFECT_SNAKE)
+    {
+        snake();
+    }
+    else
+    {
+        gl_Position = vec4(in_position, 1);
+    }
+    gl_Position = mvp * gl_Position;
     ex_color = in_color;
     x = 1.8 - abs(in_position[0]);
+    if (effect == EFFECT_WOBBLE)
+    {
+        wobble();
+    }
     uv = vertex_uv;
 }