From: ehofman <ehofman>
Date: Fri, 21 May 2004 14:50:49 +0000 (+0000)
Subject: Updates from Frederic to use 2 texture units and a color blend function rather than... 
X-Git-Url: https://git.mxchange.org/?a=commitdiff_plain;h=0f5f30b993a78fd99055a6a9ceb4b40aed1afe5b;p=simgear.git

Updates from Frederic to use 2 texture units and a color blend function rather than 3 texture units.
---

diff --git a/simgear/scene/sky/cloud.cxx b/simgear/scene/sky/cloud.cxx
index 9e848e3b..606dd52a 100644
--- a/simgear/scene/sky/cloud.cxx
+++ b/simgear/scene/sky/cloud.cxx
@@ -54,6 +54,7 @@ static GLuint normalization_cube_map;
 
 static glActiveTextureProc glActiveTexturePtr = 0;
 static glClientActiveTextureProc glClientActiveTexturePtr = 0;
+static glBlendColorProc glBlendColorPtr = 0;
 
 bool SGCloudLayer::enable_bump_mapping = false;
 
@@ -307,13 +308,15 @@ SGCloudLayer::rebuild()
         bump_mapping = SGIsOpenGLExtensionSupported("GL_ARB_multitexture") &&
                        SGIsOpenGLExtensionSupported("GL_ARB_texture_cube_map") &&
                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_combine") &&
-                       SGIsOpenGLExtensionSupported("GL_ARB_texture_env_dot3") && true;
+                       SGIsOpenGLExtensionSupported("GL_ARB_texture_env_dot3") && 
+                       SGIsOpenGLExtensionSupported("GL_ARB_imaging");
 
         if ( bump_mapping ) {
             glGetIntegerv( GL_MAX_TEXTURE_UNITS_ARB, &nb_texture_unit );
             if ( nb_texture_unit < 2 ) {
                 bump_mapping = false;
             }
+            nb_texture_unit = 2; // Force the number of units for now
         }
 
         if ( bump_mapping ) {
@@ -329,6 +332,7 @@ SGCloudLayer::rebuild()
 
             glActiveTexturePtr = (glActiveTextureProc)SGLookupFunction("glActiveTextureARB");
             glClientActiveTexturePtr = (glClientActiveTextureProc)SGLookupFunction("glClientActiveTextureARB");
+            glBlendColorPtr = (glBlendColorProc)SGLookupFunction("glBlendColor");
 
             cloud_path.set(texture_path.str());
             cloud_path.append("overcast.rgb");
@@ -850,8 +854,10 @@ void SGCloudLayer::draw( bool top ) {
 
             glDisable( GL_LIGHTING );
             glDisable( GL_CULL_FACE );
-            glEnable( GL_ALPHA_TEST );
-            glAlphaFunc ( GL_GREATER, 0.1 ) ;
+            if ( layer_coverage == SG_CLOUD_FEW ) {
+                glEnable( GL_ALPHA_TEST );
+                glAlphaFunc ( GL_GREATER, 0.01 );
+            }
             glEnable( GL_BLEND ); 
             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 
@@ -909,6 +915,8 @@ void SGCloudLayer::draw( bool top ) {
             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_DOT3_RGB_ARB );
             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
+            glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_PREVIOUS_ARB );
+            glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 
             if ( nb_texture_unit >= 3 ) {
                 glActiveTexturePtr( GL_TEXTURE2_ARB );
@@ -956,6 +964,9 @@ void SGCloudLayer::draw( bool top ) {
                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 
                 glDisableClientState( GL_COLOR_ARRAY );
+                glEnable( GL_LIGHTING );
+
+                glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 
             } else {
                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
@@ -967,7 +978,6 @@ void SGCloudLayer::draw( bool top ) {
                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 
-
                 //Disable textures
                 glDisable( GL_TEXTURE_2D );
 
@@ -987,8 +997,17 @@ void SGCloudLayer::draw( bool top ) {
                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 
 	        glDepthFunc(GL_LEQUAL);
-                //Enable multiplicative blending
-                glBlendFunc( GL_DST_COLOR, GL_ZERO );
+
+                glEnable( GL_LIGHTING );
+                sgVec4 color;
+                ssgGetLight( 0 )->getColour( GL_DIFFUSE, color );
+                float average = ( color[0] + color[1] + color[2] ) / 3.0f;
+                sgVec4 averageColor;
+                sgSetVec4( averageColor, average, average, average, 1.0f );
+                ssgGetLight( 0 )->setColour( GL_DIFFUSE, averageColor );
+
+                glBlendColorPtr( average, average, average, 1.0f );
+                glBlendFunc( GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_COLOR );
 
                 //Perform a second pass to color the torus
                 //Bind decal texture
@@ -1014,6 +1033,8 @@ void SGCloudLayer::draw( bool top ) {
                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 
+                ssgGetLight( 0 )->setColour( GL_DIFFUSE, color );
+
                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
             }
             //Disable texture
@@ -1022,10 +1043,7 @@ void SGCloudLayer::draw( bool top ) {
             glDisableClientState( GL_VERTEX_ARRAY );
             glDisableClientState( GL_NORMAL_ARRAY );
 
-            glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
-
             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
-            glEnable( GL_LIGHTING );
             glEnable( GL_CULL_FACE );
 	    glDepthFunc(GL_LESS);
 
diff --git a/simgear/screen/extensions.hxx b/simgear/screen/extensions.hxx
index b6856a77..26eb3d9d 100644
--- a/simgear/screen/extensions.hxx
+++ b/simgear/screen/extensions.hxx
@@ -82,13 +82,24 @@ inline void (*SGLookupFunction(const char *func))()
  * OpenGL 1.2 and 1.3 enumerants
  */
 
-#ifndef GL_CLAMP_TO_EDGE
+#ifndef GL_VERSION_1_2
 #define GL_CLAMP_TO_EDGE                                        0x812F
-#endif
-
-#ifndef GL_TEXTURE_WRAP_R
 #define GL_TEXTURE_WRAP_R                                       0x8072
-#endif
+#define GL_BLEND_EQUATION                                       0x8009
+#define GL_MIN                                                  0x8007
+#define GL_MAX                                                  0x8008
+#define GL_FUNC_ADD                                             0x8006
+#define GL_FUNC_SUBTRACT                                        0x800A
+#define GL_FUNC_REVERSE_SUBTRACT                                0x800B
+#define GL_BLEND_COLOR                                          0x8005
+#define GL_CONSTANT_COLOR                                       0x8001
+#define GL_ONE_MINUS_CONSTANT_COLOR                             0x8002
+#define GL_CONSTANT_ALPHA                                       0x8003
+#define GL_ONE_MINUS_CONSTANT_ALPHA                             0x8004
+#endif
+
+typedef void (APIENTRY * glBlendEquationProc) (GLenum mode );
+typedef void (APIENTRY * glBlendColorProc) (GLclampf red, GLclampf green, GLclampf blue, GLclampf alpha );
 
 
 /* OpenGL extension declarations */