From 79bfdba0f7b4e9d1668617ac463d18b1b26f10ce Mon Sep 17 00:00:00 2001
From: cwj3rcb <cwj3rcb@gmail.com>
Date: Sat, 30 Aug 2025 15:43:28 -0500
Subject: [PATCH] Chatgpt shader implementation for png transparency.

---
 README.md |  2 ++
 main.c    | 57 ++++++++++++++++++++++++++++++++++++-------------------
 2 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/README.md b/README.md
index e69de29..e9b35d1 100644
--- a/README.md
+++ b/README.md
@@ -0,0 +1,2 @@
+My first game project.
+Made using Raylib.
\ No newline at end of file
diff --git a/main.c b/main.c
index d85e5b2..878d146 100644
--- a/main.c
+++ b/main.c
@@ -2,6 +2,7 @@
 #include "rcamera.h"
 #include "raymath.h"
 #include <stdbool.h>
+#include <stddef.h>
 
 //----------------------------------------------------------------------------------
 // Defines and Macros
@@ -65,6 +66,21 @@ typedef struct
     Player player;
 } Master;
 
+// GLSL 330 core fragment shader (desktop)
+// Discards fragments with alpha below a threshold so depth is only written on real pixels.
+static const char *ALPHA_CLIP_FS = 
+"#version 330 core\n"
+"in vec2 fragTexCoord;\n"
+"in vec4 fragColor;\n"
+"uniform sampler2D texture0;\n"
+"uniform float u_alphaCutoff; // e.g., 0.3\n"
+"out vec4 finalColor;\n"
+"void main(){\n"
+"    vec4 texel = texture(texture0, fragTexCoord);\n"
+"    if(texel.a < u_alphaCutoff) discard;\n"
+"    finalColor = texel * fragColor;\n"
+"}\n";
+
 //------------------------------------------------------------------------------------
 // Function Initation
 //------------------------------------------------------------------------------------
@@ -159,6 +175,11 @@ int main(void)
     Model mdlTile = LoadModelFromMesh(meshTile);
     mdlTile.materials[0].maps[MATERIAL_MAP_ALBEDO].texture = texGrass;
 
+
+    Shader shAlphaClip = LoadShaderFromMemory(NULL, ALPHA_CLIP_FS);
+    int locCutoff = GetShaderLocation(shAlphaClip, "u_alphaCutoff");
+    float cutoff = 0.3f; // tweak to taste; 0.3–0.5 works well for tree PNGs
+    SetShaderValue(shAlphaClip, locCutoff, &cutoff, SHADER_UNIFORM_FLOAT);
     //--------------------------------------------------------------------------------------
 
     // Main game loop
@@ -281,26 +302,24 @@ int main(void)
 
                     BeginMode3D(g.player.camera);
                         DrawLevel(mdlTile);
+
+                        BeginShaderMode(shAlphaClip);
+                        {
+                            // Draw your trees here with DrawBillboard / DrawBillboardPro
+                            // Example using your positions:
+                            DrawBillboard(g.player.camera, tree, treepos, treeSize, WHITE);
+
+                            Vector3 p = treepos;
+                            p.x += 3*5; p.z += 3*5; DrawBillboard(g.player.camera, tree, p, treeSize, WHITE);
+                            p.x += 5*5; p.z += -2*5; DrawBillboard(g.player.camera, tree, p, treeSize, WHITE);
+                            p.x += -4*5; p.z += 3*5; DrawBillboard(g.player.camera, tree, p, treeSize, WHITE);
+                            p.x += 9*5; p.z += 10*5; DrawBillboard(g.player.camera, tree, p, treeSize, WHITE);
+
+                            // Your sign as a cutout too (if it has a clean alpha)
+                        }
+                        EndShaderMode();
+                        
                         DrawBillboard(g.player.camera, sign, bbPos, bbSize, WHITE);
-
-                        DrawBillboard(g.player.camera, tree, treepos, treeSize, WHITE);
-
-                        treepos.x += 3*5;
-                        treepos.z += 3*5;
-                        DrawBillboard(g.player.camera, tree, treepos, treeSize, WHITE);
-
-                        treepos.x += 5*5;
-                        treepos.z += -2*5;
-                        DrawBillboard(g.player.camera, tree, treepos, treeSize, WHITE);
-
-                        treepos.x += -4*5;
-                        treepos.z += 3*5;
-                        DrawBillboard(g.player.camera, tree, treepos, treeSize, WHITE);
-
-                        treepos.x += 9*5;
-                        treepos.z += 10*5;
-                        DrawBillboard(g.player.camera, tree, treepos, treeSize, WHITE);
-
                     EndMode3D();
 
                     // Draw info box