sdl: tweak opengl state

5 files changed, 92 insertions, 43 deletions

diff --git a/sdl/GL_notes.txt b/sdl/GL_notes.txt
index 23795e9..ac51035 100644
--- a/sdl/GL_notes.txt
+++ b/sdl/GL_notes.txt
@@ -2,6 +2,9 @@ Performance
 - Depth Testing, aka Z-buffer
 - Culling: don't render what you can't see
 
+Ideas
+- Use scissor test or bind texture for HUD display?
+
 Terms
 - Winding: by default, primitives that follow in CCW fashion are front facing
 
@@ -36,7 +39,8 @@ Terms
  - Dithering: simulate displaying wider range of colors on on systems with small
    amount of colors
  - Texture Filtering: process of calculating color fragments from a stretched or
-   shrunken texture map   
+   shrunken texture map
+ - Fragments: color values placed in the color buffer
    
 OBJ Loader
 - glGenTextures()
diff --git a/sdl/gldraw.c b/sdl/gldraw.c
index ed455e0..5430009 100644
--- a/sdl/gldraw.c
+++ b/sdl/gldraw.c
@@ -188,6 +188,10 @@ void glDrawTriangle(void)
 
 void glDrawGround(void)
 {
+    glDisable(GL_MULTISAMPLE);
+    glEnable(GL_BLEND);
+    glEnable(GL_LINE_SMOOTH);
+
     GLfloat fExtent = 20.0f;
     GLfloat fStep = 0.5f;
     GLfloat y = -0.4f;
@@ -203,6 +207,10 @@ void glDrawGround(void)
         glVertex3f(-fExtent, y, iLine);
     }
     glEnd();
+
+    glDisable(GL_LINE_SMOOTH);
+    glDisable(GL_BLEND);
+    glEnable(GL_MULTISAMPLE);
 }
 
 void glDrawUnitAxes(void)
diff --git a/sdl/platform.c b/sdl/platform.c
index 270a938..677b5b8 100644
--- a/sdl/platform.c
+++ b/sdl/platform.c
@@ -2,6 +2,7 @@
  *
  * Platform
  *
+ * Notes: Assumes multisampling is always enabled
  *
  */
 
@@ -11,15 +12,14 @@
 #include "platform.h"
 
 /* few light arrays */
-GLfloat fNoLight[]     = { 0.0f, 0.0f, 0.0f, 0.0f    };
-GLfloat fLowLight[]    = { 0.25f, 0.25f, 0.25f, 1.0f };
-GLfloat fMedLight[]    = { 0.50f, 0.50f, 0.50f, 1.0f };
-GLfloat fBrightLight[] = { 1.0f, 1.0f, 1.0f, 1.0f    };
+const GLfloat fNoLight[]     = { 0.0f, 0.0f, 0.0f, 1.0f    };
+const GLfloat fLowLight[]    = { 0.25f, 0.25f, 0.25f, 1.0f };
+const GLfloat fMedLight[]    = { 0.50f, 0.50f, 0.50f, 1.0f };
+const GLfloat fShinyLight[]  = { 0.70f, 0.70f, 0.70f, 1.0f };
+const GLfloat fBrightLight[] = { 1.0f, 1.0f, 1.0f, 1.0f    };
 
 /* light values and coordinates */
-GLfloat whiteLight[]  = { 0.05f, 0.05f, 0.05f, 1.0f };
-GLfloat sourceLight[] = { 0.75f, 0.75f, 0.75f, 1.0f };
-GLfloat lightPos[]    = { -10.f, 5.0f, 5.0f, 1.0f   };
+const GLfloat lightPos[]    = { -10.f, 5.0f, 5.0f, 1.0f   };
 
 /* variables that should be already defined and declared for us by main program */
 extern const unsigned int xres_w;
@@ -38,47 +38,74 @@ void setup_opengl(void)
     glFogf(GL_FOG_END, 20.0f);
     glFogi(GL_FOG_MODE, GL_LINEAR);   /* fog equation */
 
-    glEnable(GL_DEPTH_TEST); /* hidden surface removal */
+    glEnable(GL_DEPTH_TEST); /* hidden surface removal, aka Z-buffer */
     glFrontFace(GL_CCW);     /* counter clock-wise polygons face out */
     glEnable(GL_CULL_FACE);  /* do not calculate inside of a pyramid */
 
-    /* enable lighting */
+    /* enable lighting, primitives now need to define color properties */
     glEnable(GL_LIGHTING);
 
     /* global illumination, ambient RGBA intensity of the entire scene */
     glLightModelfv(GL_LIGHT_MODEL_AMBIENT, fLowLight);
 
     /* setup and enable light 0 */
-    glLightfv(GL_LIGHT0, GL_AMBIENT, fMedLight);
-    glLightfv(GL_LIGHT0, GL_DIFFUSE, fMedLight);
+    glLightfv(GL_LIGHT0, GL_AMBIENT,  fMedLight);
+    glLightfv(GL_LIGHT0, GL_DIFFUSE,  fShinyLight);
     glLightfv(GL_LIGHT0, GL_SPECULAR, fBrightLight);
     glLightfv(GL_LIGHT0, GL_POSITION, lightPos);
     glEnable(GL_LIGHT0);
 
-    /* enable color tracking */
-    glEnable(GL_COLOR_MATERIAL);
-
-    /* set material properties to follow glColor values */
+    /* set material properties to follow all glColor values */
     /* all primitives specified after the glMaterial call are affected by the
      * last values set, until another call to glMaterial is made */
     glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE);
+
+    /* enable color tracking, should be called after glColorMaterial */
+    glEnable(GL_COLOR_MATERIAL);
+
+    /* set globally, sets specular reflection to a white color,
+     * this call follows all subsequent primitives */
     glMaterialfv(GL_FRONT, GL_SPECULAR, fBrightLight);
-    glMateriali(GL_FRONT, GL_SHININESS, 128);
 
-    /* turn on anti aliasing for points, lines, and polygons */
+    /* default (0), by increasing this value you reduce the size and increase
+     * the focus of the specular highlight, causing a shiny spot to appear */
+    glMateriali(GL_FRONT, GL_SHININESS, 64);
+
+    /* multisampling for polygons, conflicts with *polygon* anti-aliasing */
+    /* enabled by default, that's what man page says, hmmm! */
+    glEnable(GL_MULTISAMPLE);
+
+    if (glIsEnabled(GL_MULTISAMPLE) == GL_FALSE)
+    {
+        fprintf(stderr, "OpenGL error: multisampling cannot be enabled!\n");
+        exit(-1);
+    }
+
+    /* turn off AA forever, it enables blending globally, so depth test goes out
+     * of the window, blended objects should be rendered in back to front order,
+     * also, following lines are ignored by OpenGL if multisampling is enabled */
+#if 0
+    /* turn on anti aliasing for points and lines */
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     glEnable(GL_BLEND);
     glEnable(GL_POINT_SMOOTH);
     glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);
     glEnable(GL_LINE_SMOOTH);
     glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
+#endif
 
-    /* screws up snowman, this has been replaced by superior multisampling */
-    //glEnable(GL_POLYGON_SMOOTH);
-    //glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
+    /* we will keep the blending function and hints though */
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+    glHint(GL_POINT_SMOOTH_HINT, GL_NICEST);
+    glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
 
-    /* multisampling for polygons, conflicts with *polygon* anti-aliasing */
-    glEnable(GL_MULTISAMPLE);
+    /* XXX: anisotropic filtering */
+
+#if 0
+    /* screws up snowman, this has been replaced by superior multisampling */
+    glEnable(GL_POLYGON_SMOOTH);
+    glHint(GL_POLYGON_SMOOTH_HINT, GL_NICEST);
+#endif
 
     /* how OpenGL combines the colors from texels with the color of the underlying
      * geometry is controlled by the texture environment mode */
@@ -88,8 +115,11 @@ void setup_opengl(void)
      * that specifies coordinates, ORLY? */
     glEnable(GL_TEXTURE_2D);
 
-    /* don't know about this, but why not */
+    /* specular highlights for textured items */
     glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SEPARATE_SPECULAR_COLOR);
+    /* glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_COLOR_SINGLE); */
+    /* only if lighting is disabled */
+    /* glEnable(GL_COLOR_SUM); */
 
     /* gray background */
     glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
@@ -127,7 +157,7 @@ SDL_Surface *setup_sdl_video(int w, int h, int bpp, unsigned int flags)
     return srfc;
 }
 
-void setup_sdl(void)
+SDL_Surface *setup_sdl(void)
 {
     SDL_Surface *screen;
     const SDL_VideoInfo* info = NULL;
@@ -194,6 +224,7 @@ void setup_sdl(void)
     SDL_PushEvent(&resizeEvent);
 
     /* save the surf pointer in platform */
+    return screen;
 }
 
 void setup_glew(void)
@@ -213,6 +244,6 @@ void setup_glew(void)
     GLint minor;
     glGetIntegerv(GL_MAJOR_VERSION, &major);
     glGetIntegerv(GL_MINOR_VERSION, &minor);
-    fprintf(stdout, "GLEW: detected OpenGL %d.%d\n", major, minor);
+    fprintf(stdout, "GLEW: initialized OpenGL %d.%d\n", major, minor);
 }
 
diff --git a/sdl/platform.h b/sdl/platform.h
index 8be6052..09028d1 100644
--- a/sdl/platform.h
+++ b/sdl/platform.h
@@ -1,18 +1,16 @@
 #ifndef _PLATFORM_H_
 #define _PLATFORM_H_
 
-extern GLfloat fNoLight[];
-extern GLfloat fLowLight[];
-extern GLfloat fBrightLight[];
-
-extern GLfloat whiteLight[];
-extern GLfloat sourceLight[];
-extern GLfloat lightPos[];
+extern const GLfloat fNoLight[];
+extern const GLfloat fLowLight[];
+extern const GLfloat fShinyLight[];
+extern const GLfloat fBrightLight[];
+extern const GLfloat lightPos[];
 
 /* function prototypes */
 void setup_opengl(void);
 SDL_Surface *setup_sdl_video(int, int, int, unsigned int);
-void setup_sdl(void);
+SDL_Surface *setup_sdl(void);
 void setup_glew(void);
 
 #endif
diff --git a/sdl/pyramid.c b/sdl/pyramid.c
index 4fb2b6a..42c7a22 100644
--- a/sdl/pyramid.c
+++ b/sdl/pyramid.c
@@ -61,6 +61,9 @@ static struct
     GLfloat xrot;
     GLfloat yrot;
 
+    /* SDL surface, our screen */
+    SDL_Surface *screen;
+
     SDL_TimerID timer_id;
     SDL_Cursor *my_cursor;
 } p;
@@ -173,20 +176,20 @@ static void platform_init(void)
     p.ground_list = glGenLists(2);
     p.triangle_list = p.ground_list + 1;
 
-    /* a ground with grass drawn using magneta lines */
-    glNewList(p.ground_list, GL_COMPILE);
-       //glBindTexture(GL_TEXTURE_2D, p.textures[1]);
-       glColor3ub(255, 0, 255);
-       glDrawGround();
-    glEndList();
-
     /* a triangle with a texture */
     glNewList(p.triangle_list, GL_COMPILE);
        glBindTexture(GL_TEXTURE_2D, p.textures[0]);
+       /* glBindTexture(GL_TEXTURE_2D, p.textures[1]); */
        glColor3f(1.0f, 1.0f, 1.0f);
        glDrawTriangle();
     glEndList();
 
+    /* a ground drawn using magneta lines */
+    glNewList(p.ground_list, GL_COMPILE);
+       glColor3ub(255, 0, 255);
+       glDrawGround();
+    glEndList();
+
     /* add a simple timer / callback function */
     p.timer_id = SDL_AddTimer(5000, sdlTimerCallback, &(p.camera));
 
@@ -199,6 +202,8 @@ static void platform_destroy(void)
 {
     glDeleteTextures(2, p.textures);
     glDeleteLists(p.ground_list, 2);
+
+    SDL_FreeSurface(p.screen);
 }
 
 static void render(void)
@@ -210,7 +215,6 @@ static void render(void)
     glPushMatrix();
         /* apply camera transform, and draw the ground */
         glframe_apply_camera_transform(&p.camera, 1);
-
         glCallList(p.ground_list);
 
         glPushMatrix();
@@ -225,7 +229,10 @@ static void render(void)
 
         /* draw a snowman */
         glTranslatef(0.0f, 0.0f, -7.0f);
+
+        glDisable(GL_TEXTURE_2D);
         glDrawSnowman();
+        glEnable(GL_TEXTURE_2D);
 
     /* restore the matrix state */
     glPopMatrix();
@@ -236,11 +243,12 @@ static void render(void)
 
 int main(int argc, char **argv)
 {
-    setup_sdl();
+    p.screen = setup_sdl();
     setup_glew();
     setup_opengl();
     platform_init();
     gltErrorCheck();
+    gltOpenGLInfo();
 
     unsigned int startclock;
     while (program_running)