From d8ea348867e4634d00a4f5678b39d15d98ce91fa Mon Sep 17 00:00:00 2001
From: Emil Kosz <ekosz@int.pl>
Date: Wed, 4 Jun 2025 20:26:25 +0200
Subject: [PATCH] Cloud shader, nice funny glitch

---
 game/res/shaders/clouds.frag | 17 +++++++++++++++++
 game/res/shaders/clouds.vert | 17 +++++++++++++++++
 game/src/camera.c            |  2 +-
 game/src/chunk/chunkman.h    |  2 +-
 game/src/entity/entity.h     |  2 ++
 game/src/entity/entman.c     | 18 ++++++++++++++++--
 game/src/entity/templates.c  |  6 ++++--
 game/src/graphics.c          |  3 +++
 game/src/program.c           |  6 ++++++
 game/src/program.h           |  1 +
 game/src/resources.c         | 19 +++++++++++++++----
 game/src/state.c             |  2 +-
 12 files changed, 84 insertions(+), 11 deletions(-)
 create mode 100644 game/res/shaders/clouds.frag
 create mode 100644 game/res/shaders/clouds.vert

diff --git a/game/res/shaders/clouds.frag b/game/res/shaders/clouds.frag
new file mode 100644
index 0000000..18447de
--- /dev/null
+++ b/game/res/shaders/clouds.frag
@@ -0,0 +1,17 @@
+#version 100
+
+precision mediump float;
+
+uniform sampler2D texture;
+
+varying vec2 f_uv;
+
+void main ()
+{
+  if(texture2D (texture, f_uv).a < 0.1)
+    {
+      discard;
+    }
+  
+  gl_FragColor = texture2D (texture, f_uv);
+}
diff --git a/game/res/shaders/clouds.vert b/game/res/shaders/clouds.vert
new file mode 100644
index 0000000..de17b21
--- /dev/null
+++ b/game/res/shaders/clouds.vert
@@ -0,0 +1,17 @@
+#version 100
+
+attribute vec4 position;
+attribute vec2 uv;
+
+uniform mat4 view;
+uniform mat4 projection;
+uniform mat4 model;
+uniform float time;
+
+varying vec2 f_uv;
+
+void main ()
+{
+  f_uv = (uv * 20.0) + (time * 20.0);
+  gl_Position = projection * view * model * position;
+}
diff --git a/game/src/camera.c b/game/src/camera.c
index 5321479..bc2f371 100644
--- a/game/src/camera.c
+++ b/game/src/camera.c
@@ -33,5 +33,5 @@ camera_get_view (mat4 dest)
 void
 camera_get_projection (float aspect, mat4 dest)
 {
-  glm_perspective (glm_rad (70), aspect, 0.01, 5000.0, dest);
+  glm_perspective (glm_rad (70), aspect, 0.01, 7000.0, dest);
 }
diff --git a/game/src/chunk/chunkman.h b/game/src/chunk/chunkman.h
index 9ef9708..316b413 100644
--- a/game/src/chunk/chunkman.h
+++ b/game/src/chunk/chunkman.h
@@ -9,7 +9,7 @@
 #include "../entity/entman.h"
 #include "../entity/templates.h"
 
-#define RENDER_DISTANCE 3
+#define RENDER_DISTANCE 6
 
 void chunkman_init ();
 void chunkman_update (vec3 camera_position);
diff --git a/game/src/entity/entity.h b/game/src/entity/entity.h
index 527acd3..dbfe4cd 100644
--- a/game/src/entity/entity.h
+++ b/game/src/entity/entity.h
@@ -20,6 +20,8 @@ typedef struct Entity
   vec3 position;
   vec3 rotation;
   vec3 scale;
+  /* Use RESPRG to get the int. */
+  unsigned int program;
   /* Use RESTEX to get the int. */
   unsigned int texture;
 } Entity;
diff --git a/game/src/entity/entman.c b/game/src/entity/entman.c
index 62486d9..bbc03e8 100644
--- a/game/src/entity/entman.c
+++ b/game/src/entity/entman.c
@@ -1,11 +1,17 @@
 #include "entman.h"
 
+/* TODO: Put uniforms into vertex attributes for pseudoinstancing. */
+/* TODO: Instead of having a huge far plane, render the clouds
+   seperately somehow. */
+
 extern vec3 camera_position;
+extern int last_time;
 
 Entity *player_entity;
 
 static GSequence *entities;
 static EntityMesh mesh_quad1, mesh_quad2, mesh_quad_x;
+static unsigned int last_program = -1;
 static unsigned int last_type = -1;
 static unsigned int last_texture = -1;
 
@@ -43,7 +49,8 @@ entman_init ()
     .position = { 0.0, 200.0, 0.0 },
     .scale = { 5000.0, 5000.0, 5000.0 },
     .rotation = { 90.0 },
-    .texture = RESTEX ("clouds")
+    .texture = RESTEX ("clouds"),
+    .program = RESPRG ("clouds")
   };
 
   ENTADD (sky);
@@ -169,7 +176,13 @@ entman_render_internal (gpointer data, gpointer userdata)
 
   glm_scale (model, entity->scale);
 
-  program_set_mat4 (RESPRG ("default"), "model", model);
+  if (entity->program != last_program)
+    {
+      program_use (entity->program);
+    }
+
+  program_set_mat4 (entity->program, "model", model);
+  program_set_float (entity->program, "time", last_time);
 
   if (entity->texture != last_texture)
     {
@@ -182,6 +195,7 @@ entman_render_internal (gpointer data, gpointer userdata)
       EntityMesh_bind (&to_render);
     }
   
+  last_program = entity->program;
   last_type = entity->mesh_type;
   last_texture = entity->texture;
   EntityMesh_render (&to_render);
diff --git a/game/src/entity/templates.c b/game/src/entity/templates.c
index 0e67b66..afa7f6b 100644
--- a/game/src/entity/templates.c
+++ b/game/src/entity/templates.c
@@ -27,7 +27,8 @@ ent_templates_init ()
     .position = { 0.0 },
     .scale = { 3.0, 8.0, 3.0 },
     .rotation = { 0.0 },
-    .texture = RESTEX ("tree0")
+    .texture = RESTEX ("tree0"),
+    .program = RESPRG ("default")
   };
   
   ent_templates_add ("tree", tree);
@@ -41,7 +42,8 @@ ent_templates_init ()
     .position = { 0.0 },
     .scale = { 1.0, 0.5, 1.0 },
     .rotation = { 0.0 },
-    .texture = RESTEX ("grass0")
+    .texture = RESTEX ("grass0"),
+    .program = RESPRG ("default")
   };
 
   ent_templates_add ("grass", grass);
diff --git a/game/src/graphics.c b/game/src/graphics.c
index 1b207f5..4cee223 100644
--- a/game/src/graphics.c
+++ b/game/src/graphics.c
@@ -74,6 +74,9 @@ graphics_render ()
 
   chunkman_render (camera_position, RESPRG ("chunk"));
 
+  program_use (RESPRG ("clouds"));
+  program_set_mat4 (RESPRG ("clouds"), "projection", projection);
+  program_set_mat4 (RESPRG ("clouds"), "view", view);
   program_use (RESPRG ("default"));
   program_set_mat4 (RESPRG ("default"), "projection", projection);
   program_set_mat4 (RESPRG ("default"), "view", view);
diff --git a/game/src/program.c b/game/src/program.c
index 7c2eb1c..9121cb8 100644
--- a/game/src/program.c
+++ b/game/src/program.c
@@ -78,6 +78,12 @@ program_set_vec3 (int program, const char *name, float x, float y, float z)
   glUniform3f (glGetUniformLocation (program, name), x, y, z);
 }
 
+void
+program_set_float (int program, const char *name, float value)
+{
+  glUniform1f (glGetUniformLocation (program, name), value);
+}
+
 void
 program_set_int_array (int program, const char *name, size_t count, int *value)
 {
diff --git a/game/src/program.h b/game/src/program.h
index a610a0a..c6a5456 100644
--- a/game/src/program.h
+++ b/game/src/program.h
@@ -11,6 +11,7 @@
 void shader_fail (int shader);
 void program_fail (int program);
 int program_create (const char *v_src, const char *f_src);
+void program_set_float (int program, const char *name, float value);
 void program_set_int_array (int program, const char *name, size_t count, int *value);
 void program_set_vec3 (int program, const char *name, float x, float y, float z);
 void program_set_mat4 (int program, const char *name, mat4 value);
diff --git a/game/src/resources.c b/game/src/resources.c
index c3095fa..9d4842d 100644
--- a/game/src/resources.c
+++ b/game/src/resources.c
@@ -10,7 +10,8 @@ resources_load_program (const char *v_path, const char *f_path)
 
   if (v_file == NULL)
     {
-      WARN ("File `%s' does not exist.", v_path); 
+      WARN ("File `%s' does not exist.", v_path);
+      return 0;
     }
   
   fseek (v_file, 0L, SEEK_END);
@@ -23,7 +24,8 @@ resources_load_program (const char *v_path, const char *f_path)
 
   if (f_file == NULL)
     {
-      WARN ("File `%s' does not exist.", f_path); 
+      WARN ("File `%s' does not exist.", f_path);
+      return 0;
     }
   
   fseek (f_file, 0L, SEEK_END);
@@ -46,6 +48,7 @@ resources_load_texture (const char *path)
   if (surface == NULL)
     {
       WARN ("Failed to load texture from path %s: %s", path, SDL_GetError ());
+      return 0;
     }
 
   unsigned int texture = texture_create (surface->w, surface->h, surface->pixels);
@@ -55,13 +58,19 @@ resources_load_texture (const char *path)
 static inline void
 resources_add_program (char *key, unsigned int program)
 {
-  g_hash_table_insert (programs, key, GINT_TO_POINTER (program));
+  if (program)
+    {
+      g_hash_table_insert (programs, key, GINT_TO_POINTER (program)); 
+    }
 }
 
 static inline void
 resources_add_texture (char *key, unsigned int texture)
 {
-  g_hash_table_insert (textures, key, GINT_TO_POINTER (texture));
+  if (texture)
+    {
+      g_hash_table_insert (textures, key, GINT_TO_POINTER (texture)); 
+    }
 }
 
 unsigned int
@@ -89,6 +98,8 @@ resources_init ()
   
   RAP ("default",  RLP ("res/shaders/default.vert", "res/shaders/default.frag"));
   RAP ("chunk",    RLP ("res/shaders/chunk.vert", "res/shaders/chunk.frag"));
+  RAP ("clouds",   RLP ("res/shaders/clouds.vert", "res/shaders/clouds.frag"));
+  
   RAT ("terrain0", RLT ("res/textures/dirt.png"));
   RAT ("terrain1", RLT ("res/textures/drygrass.png"));
   RAT ("terrain2", RLT ("res/textures/grass.png"));
diff --git a/game/src/state.c b/game/src/state.c
index b9f0f1f..5b8b491 100644
--- a/game/src/state.c
+++ b/game/src/state.c
@@ -4,7 +4,7 @@ extern vec3 camera_position;
 extern Entity *player_entity;
 
 float delta_time;
-static int last_time;
+int last_time;
 
 void
 game_state_init (int ticks)