gamnit: pass the elapsed time in the world of each sprite set to the shader

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/gamnit/flat.nit b/lib/gamnit/flat.nit
index b278029..b70d010 100644 (file)
--- a/lib/gamnit/flat.nit
+++ b/lib/gamnit/flat.nit
@@ -393,6 +393,7 @@ redef class App
                perf_clock_main.lapse
                var dt = clock.lapse.to_f
                update dt
+               frame_dt = dt
                sys.perfs["gamnit flat update client"].add perf_clock_main.lapse
 
                # Draw and flip screen
@@ -404,6 +405,8 @@ redef class App
                assert gl_error == gl_NO_ERROR else print_error gl_error
        end
 
+       private var frame_dt = 0.0
+
        # Draw the whole screen, all `glDraw...` calls should be executed here
        protected fun frame_core_draw(display: GamnitDisplay)
        do
@@ -425,6 +428,9 @@ redef class App
                simple_2d_program.use
                simple_2d_program.mvp.uniform camera.mvp_matrix
 
+               sprite_set.time += frame_dt*sprite_set.time_mod
+               simple_2d_program.time.uniform sprite_set.time
+
                # draw
                sprite_set.draw
        end
@@ -507,6 +513,9 @@ private class Simple2dProgram
                // Model view projection matrix
                uniform mat4 mvp;
 
+               // Current world time, in seconds
+               uniform float time;
+
                // Rotation matrix
                attribute vec4 rotation_row0;
                attribute vec4 rotation_row1;
@@ -675,6 +684,12 @@ private class SpriteSet
        # Sprites needing resorting in `contexts_map`
        var sprites_to_remap = new Array[Sprite]
 
+       # Animation speed multiplier (0.0 to pause, 1.0 for normal speed, etc.)
+       var time_mod = 1.0 is writable
+
+       # Seconds elapsed since the launch of the program, in world time responding to `time_mod`
+       var time = 0.0
+
        # Add a sprite to the appropriate context
        fun map_sprite(sprite: Sprite)
        do