From 11a87361982434aab125a88468760c0d9a81ed05 Mon Sep 17 00:00:00 2001
From: Hayden K <819028+mrneo240@users.noreply.github.com>
Date: Wed, 17 Apr 2019 14:29:50 -0400
Subject: [PATCH] feat: add gl EXT handing for mipmap - comes from gl1.4 - new
 defines - expand glTexEnvi

---
 GL/texture.c    | 63 ++++++++++++++++++++++++++++++++++---------------
 include/glext.h | 15 ++++++++++++
 2 files changed, 59 insertions(+), 19 deletions(-)

diff --git a/GL/texture.c b/GL/texture.c
index ea902eb..cf8971e 100644
--- a/GL/texture.c
+++ b/GL/texture.c
@@ -402,18 +402,13 @@ void APIENTRY glBindTexture(GLenum  target, GLuint texture) {
 void APIENTRY glTexEnvi(GLenum target, GLenum pname, GLint param) {
     TRACE();
 
-    GLint target_values [] = {GL_TEXTURE_ENV, 0};
-    GLint pname_values [] = {GL_TEXTURE_ENV_MODE, 0};
-    GLint param_values [] = {GL_MODULATE, GL_DECAL, GL_REPLACE, 0};
-
     GLubyte failures = 0;
 
+    GLint target_values [] = {GL_TEXTURE_ENV, GL_TEXTURE_FILTER_CONTROL_EXT, 0};
     failures += _glCheckValidEnum(target, target_values, __func__);
-    failures += _glCheckValidEnum(pname, pname_values, __func__);
-    failures += _glCheckValidEnum(param, param_values, __func__);
 
     TextureObject* active = TEXTURE_UNITS[ACTIVE_TEXTURE];
-
+    
     if(!active) {
         return;
     }
@@ -421,20 +416,49 @@ void APIENTRY glTexEnvi(GLenum target, GLenum pname, GLint param) {
     if(failures) {
         return;
     }
+    switch(target){
+        case GL_TEXTURE_ENV:
+            {
+            GLint pname_values [] = {GL_TEXTURE_ENV_MODE, 0};
+            GLint param_values [] = {GL_MODULATE, GL_DECAL, GL_REPLACE, 0};
+            failures += _glCheckValidEnum(pname, pname_values, __func__);
+            failures += _glCheckValidEnum(param, param_values, __func__);
+            
+            if(failures) {
+                return;
+            }
 
-    switch(param) {
-    case GL_MODULATE:
-        active->env = PVR_TXRENV_MODULATEALPHA;
-    break;
-    case GL_DECAL:
-        active->env = PVR_TXRENV_DECAL;
-    break;
-    case GL_REPLACE:
-        active->env = PVR_TXRENV_REPLACE;
-    break;
-    default:
-        break;
+            switch(param) {
+                case GL_MODULATE:
+                    active->env = PVR_TXRENV_MODULATEALPHA;
+                break;
+                case GL_DECAL:
+                    active->env = PVR_TXRENV_DECAL;
+                break;
+                case GL_REPLACE:
+                    active->env = PVR_TXRENV_REPLACE;
+                break;
+                default:
+                    break;
+            }
+            }
+            break;
+
+        case GL_TEXTURE_FILTER_CONTROL_EXT:
+            {
+            GLint pname_values [] = {GL_TEXTURE_LOD_BIAS_EXT, 0};
+            failures += _glCheckValidEnum(pname, pname_values, __func__);
+            failures += (param > GL_MAX_TEXTURE_LOD_BIAS_DEFAULT || param < -GL_MAX_TEXTURE_LOD_BIAS_DEFAULT); 
+            if(failures) {
+                return;
+            }
+            active->mipmap_bias = (GL_MAX_TEXTURE_LOD_BIAS_DEFAULT+1)+param; // bring to 1-15 inclusive
+            }
+            break;
+        default:
+           break;
     }
+  
 }
 
 void APIENTRY glCompressedTexImage2DARB(GLenum target,
@@ -916,6 +940,7 @@ void APIENTRY glTexImage2D(GLenum target, GLint level, GLint internalFormat,
             active->data = NULL;
             active->mipmap = 0;
             active->mipmapCount = 0;
+            active->mipmap_bias = GL_KOS_INTERNAL_DEFAULT_MIPMAP_LOD_BIAS; // in the scale of -8 - 8 moved to 1-15, -4 = 4 
             active->dataStride = 0;
         }
     }
diff --git a/include/glext.h b/include/glext.h
index af64ff2..15cfa7f 100644
--- a/include/glext.h
+++ b/include/glext.h
@@ -190,6 +190,21 @@ GLAPI void APIENTRY glCompressedTexImage2DARB(GLenum target,
 #define glGenerateMipmap glGenerateMipmapEXT
 #define glCompressedTexImage2D glCompressedTexImage2DARB
 
+#ifndef GL_VERSION_1_4
+#define GL_VERSION_1_4 1
+#define GL_MAX_TEXTURE_LOD_BIAS           0x84FD
+#define GL_TEXTURE_LOD_BIAS               0x8501
+#define GL_MAX_TEXTURE_LOD_BIAS_DEFAULT 7
+#define GL_KOS_INTERNAL_DEFAULT_MIPMAP_LOD_BIAS -4
+#endif
+
+#ifndef GL_EXT_texture_lod_bias
+#define GL_EXT_texture_lod_bias 1
+#define GL_MAX_TEXTURE_LOD_BIAS_EXT       0x84FD
+#define GL_TEXTURE_FILTER_CONTROL_EXT     0x8500
+#define GL_TEXTURE_LOD_BIAS_EXT           0x8501
+#endif /* GL_EXT_texture_lod_bias */
+
 __END_DECLS
 
 #endif /* !__GL_GLEXT_H */