preparatory work for anisotropy

1 files changed, 189 insertions, 0 deletions

diff --git a/tests/aniso.c b/tests/aniso.c
new file mode 100644
index 00000000..f2735f49
--- /dev/null
+++ b/tests/aniso.c
@@ -0,0 +1,189 @@
+/*******************************************************************
+ *                                                                 *
+ *                        Using SDL With OpenGL                    *
+ *                                                                 *
+ *                    Tutorial by Kyle Foley (sdw)                 *
+ *                                                                 *
+ * http://gpwiki.org/index.php/SDL:Tutorials:Using_SDL_with_OpenGL *
+ *                                                                 *
+ *******************************************************************/
+
+/*
+THIS WORK, INCLUDING THE SOURCE CODE, DOCUMENTATION
+AND RELATED MEDIA AND DATA, IS PLACED INTO THE PUBLIC DOMAIN.
+
+THE ORIGINAL AUTHOR IS KYLE FOLEY.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+#include "SDL/SDL.h"
+#include "SDL/SDL_image.h"
+#include "SDL/SDL_opengl.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+#define MAX(x, y) ((x) > (y) ? (x) : (y))
+
+int hasext(const char *exts, const char *ext) // from cube2, zlib licensed
+{
+    int len = strlen(ext);
+    if(len) for(const char *cur = exts; (cur = strstr(cur, ext)); cur += len)
+    {
+        if((cur == exts || cur[-1] == ' ') && (cur[len] == ' ' || !cur[len])) return 1;
+    }
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    SDL_Surface *screen;
+
+    // Slightly different SDL initialization
+    if ( SDL_Init(SDL_INIT_VIDEO) != 0 ) {
+        printf("Unable to initialize SDL: %s\n", SDL_GetError());
+        return 1;
+    }
+
+    SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); // *new*
+
+    screen = SDL_SetVideoMode( 640, 480, 16, SDL_OPENGL ); // *changed*
+    if ( !screen ) {
+        printf("Unable to set video mode: %s\n", SDL_GetError());
+        return 1;
+    }
+
+    // Check extensions
+
+    const char *exts = (const char *)glGetString(GL_EXTENSIONS);
+    assert(hasext(exts, "GL_EXT_texture_filter_anisotropic"));
+    
+    GLint aniso;
+    glGetIntegerv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &aniso);
+    printf("Max anisotropy: %d\n", aniso);
+    assert(aniso >= 4);
+
+    // Set the OpenGL state after creating the context with SDL_SetVideoMode
+
+    glClearColor( 0, 0, 0, 0 );
+    
+#if !EMSCRIPTEN
+    glEnable( GL_TEXTURE_2D ); // Need this to display a texture XXX unnecessary in OpenGL ES 2.0/WebGL
+#endif
+
+    glViewport( 0, 0, 800, 600 );
+
+    glMatrixMode( GL_PROJECTION );
+    GLfloat matrixData[] = { 2.0/640,        0,        0,  0,
+                                   0, -2.0/480,        0,  0,
+                                   0,        0, -2.0/480,  0,
+                                  -1,        1,        0,  1 };
+    glLoadMatrixf(matrixData); // test loadmatrix
+
+    glMatrixMode( GL_MODELVIEW );
+    glLoadIdentity();
+
+
+    // Load the OpenGL texture
+
+    GLuint texture, texture2;
+
+    const int DDS_SIZE = 43920;
+    FILE *dds = fopen("water.dds", "rb");
+    assert(dds);
+    char *ddsdata = (char*)malloc(DDS_SIZE);
+    assert(fread(ddsdata, 1, DDS_SIZE, dds) == DDS_SIZE);
+    fclose(dds);
+
+    {
+      glGenTextures( 1, &texture );
+      glBindTexture( GL_TEXTURE_2D, texture );
+
+      char *curr = ddsdata + 128;
+      int level = 0;
+      int w = 512;
+      int h = 64;
+      while (level < 5) {
+        printf("uploading level %d: %d, %d\n", level, w, h);
+        assert(!glGetError());
+        glCompressedTexImage2D(GL_TEXTURE_2D, level, GL_COMPRESSED_RGBA_S3TC_DXT5_EXT, w, h, 0, w*h, curr);
+        assert(!glGetError());
+        curr += MAX(w, 4)*MAX(h, 4);
+        w /= 2;
+        h /= 2;
+        level++;
+      }
+      glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
+      glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
+    }
+    {
+      glGenTextures( 1, &texture2 );
+      glBindTexture( GL_TEXTURE_2D, texture2 );
+
+      char *curr = ddsdata + 128;
+      int level = 0;
+      int w = 512;
+      int h = 64;
+      while (level < 5) {
+        printf("uploading level %d: %d, %d\n", level, w, h);
+        assert(!glGetError());
+        glCompressedTexImage2D(GL_TEXTURE_2D, level, GL_COMPRESSED_RGBA_S3TC_DXT5_EXT, w, h, 0, w*h, curr);
+        assert(!glGetError());
+        curr += MAX(w, 4)*MAX(h, 4);
+        w /= 2;
+        h /= 2;
+        level++;
+      }
+      glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
+      glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
+      glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, 4);
+    }
+
+    // Prepare and Render
+
+    // Clear the screen before drawing
+    glClear( GL_COLOR_BUFFER_BIT );
+    
+    // Bind the texture to which subsequent calls refer to
+    int w = 8;
+    int n = 20;
+    for (int x = 0; x < n; x++) {
+      for (int y = 0; y < n*2; y++) {
+        glBindTexture( GL_TEXTURE_2D, texture );
+        glBegin( GL_TRIANGLE_STRIP );
+          glTexCoord2i( 0, 0 ); glVertex3f( x*w,           y*(w), 0 );
+          glTexCoord2i( 1, 0 ); glVertex3f( (x+1)*(w-2*y/n),     y*(w), 0 );
+          glTexCoord2i( 1, 1 ); glVertex3f( (x+1)*(w-2*y/n), (y+1)*(w), 0 );
+          glTexCoord2i( 0, 1 ); glVertex3f( x*w,       (y+1)*(w), 0 );
+        glEnd();
+        glBindTexture( GL_TEXTURE_2D, texture2 );
+        glBegin( GL_TRIANGLE_STRIP );
+          glTexCoord2i( 0, 0 ); glVertex3f( n*w + x*w,           y*(w), 0 );
+          glTexCoord2i( 1, 0 ); glVertex3f( n*w + (x+1)*(w-2*y/n),     y*(w), 0 );
+          glTexCoord2i( 1, 1 ); glVertex3f( n*w + (x+1)*(w-2*y/n), (y+1)*(w), 0 );
+          glTexCoord2i( 0, 1 ); glVertex3f( n*w + x*w,       (y+1)*(w), 0 );
+        glEnd();
+      }
+    }
+
+    SDL_GL_SwapBuffers();
+    
+#if !EMSCRIPTEN
+    // Wait for 3 seconds to give us a chance to see the image
+    SDL_Delay(10000);
+#endif
+
+    // Now we can delete the OpenGL texture and close down SDL
+    glDeleteTextures( 1, &texture );
+    
+    SDL_Quit();
+    
+    return 0;
+}