From f8f62312f9b6893c56037758aa6c78a7f352a84d Mon Sep 17 00:00:00 2001
From: Mylloon <kennel.anri@tutanota.com>
Date: Sun, 21 May 2023 20:32:08 +0200
Subject: [PATCH] smoot ltr animation? kinda

---
 shaders/tag.fs | 12 +++++++++++-
 src/tag.c      | 24 ++++++++++++++++--------
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/shaders/tag.fs b/shaders/tag.fs
index 3c0a5aa..a7bf4cc 100644
--- a/shaders/tag.fs
+++ b/shaders/tag.fs
@@ -8,8 +8,13 @@ in vec2 vsoTexCoord;
 out vec4 fragColor;
 
 uniform sampler2D tex0;
+uniform sampler2D tex1;
 uniform mat4 viewMatrix;
 uniform vec4 lumPos;
+uniform float fadeAmount;
+
+const float fadeStart = 0;
+const float fadeEnd = 1;
 
 void main(void) {
   const vec3 Vu = vec3(0, 0, -1);
@@ -19,5 +24,10 @@ void main(void) {
   float ispec = pow(clamp(dot(-Vu, reflexion), 0., 1.), 20);
   float phongIL = clamp(dot(-Ld, vsoNormal), 0., 1.);
 
-  fragColor = phongIL * texture(tex0, vsoTexCoord) + ispec * vec4(1);
+  vec4 color1 = texture(tex0, vsoTexCoord);
+  vec4 color2 = texture(tex1, vsoTexCoord);
+  float fadeFactor = smoothstep(fadeStart, fadeEnd, 1 - vsoTexCoord.x);
+
+  fragColor = phongIL * mix(color1, color2, fadeFactor * fadeAmount) + ispec * vec4(1);
+
 }
diff --git a/src/tag.c b/src/tag.c
index b385191..b50cd70 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -2,7 +2,7 @@
 
 static GLuint _pId = 0;
 static GLuint _murId = 0;
-static GLuint _texId = 0;
+static GLuint _texId[2] = {0};
 
 static const char *matrix_proj = "proj";
 static const char *matrix_model = "model";
@@ -35,14 +35,15 @@ static void init(void) {
   _murId = gl4dgGenGrid2df(100, 100);
   _pId = gl4duCreateProgram("<vs>shaders/tag.vs", "<fs>shaders/tag.fs", NULL);
 
-  glGenTextures(1, &_texId);
-  load_img("images/wall.png", _texId);
+  glGenTextures(2, _texId);
+  load_img("images/wall.png", _texId[0]);
+  load_img("images/wall.png", _texId[1]);
 
   TTF_Font *font = NULL;
   if (initFont(&font, "fonts/Instrument.ttf", 100)) {
     exit(3);
   }
-  if (writeText(&_texId, font, "macron = loser", (SDL_Color){0, 0, 0, 255},
+  if (writeText(&_texId[1], font, "macron = loser", (SDL_Color){0, 0, 0, 255},
                 GL_TRUE)) {
     exit(3);
   }
@@ -86,10 +87,17 @@ static void draw(void) {
   gl4duSendMatrices();
 
   glActiveTexture(GL_TEXTURE0);
-  glBindTexture(GL_TEXTURE_2D, _texId);
+  glBindTexture(GL_TEXTURE_2D, _texId[0]);
   glUniform1f(glGetUniformLocation(_pId, "phase"), 0);
   glUniform4fv(glGetUniformLocation(_pId, "lumPos"), 1, lum_pos);
 
+  glActiveTexture(GL_TEXTURE1);
+  glBindTexture(GL_TEXTURE_2D, _texId[1]);
+  GLfloat fade_amout = (GLfloat)t0 / 7000.f;
+  glUniform1f(glGetUniformLocation(_pId, "fadeAmount"), fade_amout);
+  glUniform1i(glGetUniformLocation(_pId, "tex0"), 0);
+  glUniform1i(glGetUniformLocation(_pId, "tex1"), 1);
+
   gl4dgDraw(_murId);
 
   glUseProgram(0);
@@ -97,8 +105,8 @@ static void draw(void) {
 }
 
 static void deinit(void) {
-  if (_texId) {
-    glDeleteTextures(1, &_texId);
-    _texId = 0;
+  if (_texId[0]) {
+    glDeleteTextures(sizeof(_texId) / sizeof(*_texId), _texId);
+    _texId[0] = 0;
   }
 }