a-game

commit 704f18b717c404b6a6cd96ec2290534990236aa1
parent c75172ff8195c05adc80689819b54f2f73f635db
Author: amin <dev@aminmesbah.com>
Date:   Wed, 24 Apr 2019 00:00:21 +0000

Capture a failing test case for the lingering bug

The collision assert fails rather frequently just after start up with
this initial position and velocity.

FossilOrigin-Name: 5cc64ce2fef71598cfb59b2c34d50aed0148a5aa1ae1e2ffcc7376a62a51deb2
Diffstat:
M
src/game.c
 | 
24
++++++++++++++++++++----
M
src/glmth.h
 | 
12
++++++++++++

2 files changed, 32 insertions(+), 4 deletions(-)
diff --git a/src/game.c b/src/game.c
@@ -14,8 +14,11 @@ internal void game_init(struct GameMemory *game_memory, v2u framebuffer)
     struct GameState *game_state = game_memory->game_state;
 
     // init player
-    game_state->player.pos = (v2) {12.5f, 5.0f};
-
+    //game_state->player.pos = (v2) {12.5f, 5.0f};
+    game_state->player.pos = (v2) {10.812491f, 3.752474f};
+    game_state->player.velocity = (v2) {0.0f, 5.0f};
+    game_state->player.pos = (v2) {10.736823f, 3.591690f};
+    game_state->player.velocity = (v2) {5.0f, 5.0f};
     // In Knytt, the player is 9 by 14 texels and a tile is 24 by 24 texels.
     // These dimensions are relative to a square 'meter', one tile
     game_state->player.dimensions = (v2) {0.375f, 0.583f};
@@ -116,7 +119,9 @@ internal struct WallCollision get_wall_collision(v2 entity_p_initial, v2 entity_
                 && collision_point.E[wall_axis] <= wall.max.E[wall_axis])
             {
                 result.collision_occurred = true;
-                result.distance_scale_factor = segment_scale_factor - 0.0001f;
+                result.distance_scale_factor = glmth_max(
+                        0.0f,
+                        segment_scale_factor - 0.0001f);
             }
         }
     }
@@ -266,6 +271,10 @@ void game_update_and_render(struct GameMemory *game_memory, struct GameInput *ga
                     if (player_is_in_tile && tile_id > 0)
                     {
                         color = (v3) {0.8f, 0.4f, 0.4f};
+                        printf("!!!!!!!!!!!!!!!!\n");
+                        glmth_print(glmth_v2_a(player.pos, glmth_v2f_m(player.dimensions, 0.5f)));
+                        glmth_print(player.velocity);
+                        assert(false);
                     }
                 }
 
@@ -286,7 +295,8 @@ void game_update_and_render(struct GameMemory *game_memory, struct GameInput *ga
         f32 dt = game_input->dt;
         f32 max_meters_per_second = 5.0f;
         f32 acceleration_rate = 50.0f;
-        f32 friction = 0.7f;
+        //f32 friction = 0.7f;
+        f32 friction = 1.0f;
 
         if (game_input->key_up)
         {
@@ -371,6 +381,7 @@ void game_update_and_render(struct GameMemory *game_memory, struct GameInput *ga
 #else
         {
 #define RENDER_COLLISION_DEBUG_QUAD(r, c) render_debug_quad(game_state, (r), (c), &view, &projection);
+            printf("--------------\n");
             v2 old_p = player->pos;
             v2 new_p = glmth_v2_a(old_p, glmth_v2f_m(player->velocity, dt));
 
@@ -399,6 +410,7 @@ void game_update_and_render(struct GameMemory *game_memory, struct GameInput *ga
             f32 remaining_time_factor = 1.0f;
             for (u32 i = 0; i < 4 && remaining_time_factor > 0.0f; i++)
             {
+                printf("Iteration %u:\n", i);
                 old_p = player->pos;
                 new_p = glmth_v2_a(old_p, glmth_v2f_m(player->velocity, dt));
                 player_delta = glmth_v2_s(new_p, old_p);
@@ -508,6 +520,10 @@ void game_update_and_render(struct GameMemory *game_memory, struct GameInput *ga
                     glmth_v2f_m(player_delta, glmth_v2_dot(player->velocity, wall_normal))
                 );
                 remaining_time_factor -= smallest_distance_scale_factor * remaining_time_factor;
+                glmth_print(player_delta);
+                glmth_print(glmth_v2_a(player->pos, glmth_v2f_m(player->dimensions, 0.5f)));
+                glmth_print(player->velocity);
+                printf("time remaining: %f\n", remaining_time_factor);
             }
         }
 #undef RENDER_COLLISION_DEBUG_QUAD
diff --git a/src/glmth.h b/src/glmth.h
@@ -179,6 +179,11 @@ internal inline f32 glmth_v2_dot(v2 vec1, v2 vec2)
 {
     // dot product, a.k.a. inner product or scalar product
     f32 dot_product = (vec1.x * vec2.x) + (vec1.y * vec2.y);
+    // NOTE: this value happens to be:
+    //     |vec1| * |vec2| * Cos(theta)
+    // where theta is the angle between vec1 and vec2. This is useful in all
+    // sorts of ways: What if theta is zero? What if vec1 or vec2 is a unit
+    // vector?
     return dot_product;
 }
 
@@ -196,6 +201,13 @@ internal inline v3 glmth_v3_cross(v3 vec1, v3 vec2)
 internal inline f32 glmth_v3_length(v3 v)
 {
     // TODO: Use inner product of v with itself
+    // NOTE: glmth_v3_dot(v, v) returns:
+    //     |v| * |v| * Cos(theta)
+    // We know that theta, the angle between v and itself, is always 0, so we
+    // know that Cos(theta) is always 1. We can then simplify the above
+    // expression to be:
+    //     (|v|)^2
+    // so sqrtf(glmth_v3_dot(v, v)) is the length of v
     return sqrtf((v.x * v.x) + (v.y * v.y) + (v.z * v.z));
 }