Detect multiple mipmap levels being uploaded to glCompressedTexImage2D

GL/error.c

@@ -40,29 +40,23 @@ static void _glKosResetError() {
     sprintf(error_function, "\n");
 }
 
+static const char* _glErrorEnumAsString(GLenum error) {
+    switch(error) {
+        case GL_INVALID_ENUM: return "GL_INVALID_ENUM";
+        case GL_OUT_OF_MEMORY: return "GL_OUT_OF_MEMORY";
+        case GL_INVALID_OPERATION: return "GL_INVALID_OPERATION";
+        case GL_INVALID_VALUE: return "GL_INVALID_VALUE";
+        default:
+            return "GL_UNKNOWN_ERROR";
+    }
+}
+
 void _glKosPrintError() {
     if(!_glKosHasError()) {
         return;
     }
 
-    printf("\nKOS GL ERROR THROWN BY FUNCTION: %s\n", error_function);
-
-    switch(last_error) {
-    case GL_INVALID_ENUM:
-        printf("KOS GL ERROR: GL_INVALID_ENUM\n");
-    break;
-    case GL_OUT_OF_MEMORY:
-        printf("KOS GL ERROR: GL_OUT_OF_MEMORY\n");
-    break;
-    case GL_INVALID_OPERATION:
-        printf("KOS GL ERROR: GL_INVALID_OPERATION\n");
-    break;
-    case GL_INVALID_VALUE:
-        printf("KOS GL ERROR: GL_INVALID_VALUE\n");
-    break;
-    default:
-        break;
-    }
+    fprintf(stderr, "GL ERROR: %s when calling %s\n", _glErrorEnumAsString(last_error), error_function);
 }
 
 GLenum glGetError(void) {

GL/texture.c

@@ -200,6 +200,22 @@ void APIENTRY glCompressedTexImage2DARB(GLenum target,
         _glKosThrowError(GL_INVALID_OPERATION, __func__);
     }
 
+    /* Guess whether we have mipmaps or not */
+
+    /* `expected` is the uncompressed size */
+    GLuint expected = sizeof(GLshort) * width * height;
+
+    /* The ratio is the uncompressed vs compressed data size */
+    GLuint ratio = (GLuint) (((GLfloat) expected) / ((GLfloat) imageSize));
+
+    if(ratio < 7) {
+        /* If the ratio is less than 1:7 then we assume that the reason for that
+        is the extra data used for mipmaps. Testing shows that a single VQ compressed
+        image is around 1:7 or 1:8. We may need to tweak this if it detects false positives */
+        fprintf(stderr, "GL ERROR: Detected multiple mipmap levels being uploaded to %s\n", __func__);
+        _glKosThrowError(GL_INVALID_OPERATION, __func__);
+    }
+
     if(_glKosHasError()) {
         _glKosPrintError();
         return;

samples/nehe06_vq/main.c

@@ -3,6 +3,7 @@
 #include "gl.h"
 #include "glu.h"
 #include "glkos.h"
+#include "glext.h"
 
 extern uint8 romdisk[];
 KOS_INIT_ROMDISK(romdisk);
@@ -56,6 +57,9 @@ int ImageLoad(char *filename, Image *image) {
     image->sizeY = header.height;
     image->dataSize = header.size;
 
+    GLuint expected = 2 * header.width * header.height;
+    GLuint ratio = (GLuint) (((GLfloat) expected) / ((GLfloat) header.size));
+
     fread(image->data, image->dataSize, 1, file);
     fclose(file);