// Scale image function
int res_scale_surface(gr_surface source, gr_surface* destination, float scale_w, float scale_h) {
GGLContext *gl = NULL;
GGLSurface* sc_mem_surface = NULL;
*destination = NULL;
GGLSurface *surface = (GGLSurface*)source;
int w = gr_get_width(source), h = gr_get_height(source);
int sx = 0, sy = 0, dx = 0, dy = 0;
float dw = (float)w * scale_w;
float dh = (float)h * scale_h;
// Create a new surface that is the appropriate size
sc_mem_surface = init_display_surface((int)dw, (int)dh);
if (!sc_mem_surface) {
printf("gr_scale_surface failed to init_display_surface\n");
return -1;
}
sc_mem_surface->format = surface->format;
// Initialize the context
gglInit(&gl);
gl->colorBuffer(gl, sc_mem_surface);
gl->activeTexture(gl, 0);
// Enable or disable blending based on source surface format
if (surface->format == GGL_PIXEL_FORMAT_RGBX_8888) {
gl->disable(gl, GGL_BLEND);
} else {
gl->enable(gl, GGL_BLEND);
gl->blendFunc(gl, GGL_ONE, GGL_ZERO);
}
// Bind our source surface to the context
gl->bindTexture(gl, surface);
// Deal with the scaling
gl->texParameteri(gl, GGL_TEXTURE_2D, GGL_TEXTURE_MIN_FILTER, GGL_LINEAR);
gl->texParameteri(gl, GGL_TEXTURE_2D, GGL_TEXTURE_MAG_FILTER, GGL_LINEAR);
gl->texParameteri(gl, GGL_TEXTURE_2D, GGL_TEXTURE_WRAP_S, GGL_CLAMP);
gl->texParameteri(gl, GGL_TEXTURE_2D, GGL_TEXTURE_WRAP_T, GGL_CLAMP);
gl->texEnvi(gl, GGL_TEXTURE_ENV, GGL_TEXTURE_ENV_MODE, GGL_REPLACE);
gl->texGeni(gl, GGL_S, GGL_TEXTURE_GEN_MODE, GGL_AUTOMATIC);
gl->texGeni(gl, GGL_T, GGL_TEXTURE_GEN_MODE, GGL_AUTOMATIC);
gl->enable(gl, GGL_TEXTURE_2D);
int32_t grad[8];
memset(grad, 0, sizeof(grad));
// s, dsdx, dsdy, scale, t, dtdx, dtdy, tscale <- this is wrong!
// This api uses block floating-point for S and T texture coordinates.
// All values are given in 16.16, scaled by 'scale'. In other words,
// set scale to 0, for 16.16 values.
// s, dsdx, dsdy, t, dtdx, dtdy, sscale, tscale
float dsdx = (float)w / dw;
float dtdy = (float)h / dh;
grad[0] = ((float)sx - (dsdx * dx)) * 65536;
grad[1] = dsdx * 65536;
grad[3] = ((float)sy - (dtdy * dy)) * 65536;
grad[5] = dtdy * 65536;
// printf("blit: w=%d h=%d dx=%d dy=%d dw=%f dh=%f dsdx=%f dtdy=%f s0=%x dsdx=%x t0=%x dtdy=%x\n",
// w, h, dx, dy, dw, dh, dsdx, dtdy, grad[0], grad[1], grad[3], grad[5]);
gl->texCoordGradScale8xv(gl, 0 /*tmu*/, grad);
// draw / scale the source surface to our target context
gl->recti(gl, dx, dy, dx + dw, dy + dh);
gglUninit(gl);
gl = NULL;
// put the scaled surface in our destination
*destination = (gr_surface*) sc_mem_surface;
// free memory used in the source
res_free_surface(source);
source = NULL;
return 0;
}
