Fix application of mask to foreground

1 files changed, 19 insertions, 10 deletions

diff --git a/main.c b/main.c
index e629966..260328c 100644
--- a/main.c
+++ b/main.c
@@ -12,10 +12,8 @@ SDL_Texture *createTiledTexture(SDL_Renderer *context, const char *filename) {
 	int tile_h = texture_surface->h;
 	SDL_FreeSurface(texture_surface);
 
-	Uint32 pixelformat;
-	SDL_QueryTexture(texture_tile, &pixelformat, 0, 0, 0);
 	SDL_Texture *texture = SDL_CreateTexture(context,
-		       	pixelformat,
+		       	SDL_PIXELFORMAT_RGBA8888,
 		       	SDL_TEXTUREACCESS_STATIC | SDL_TEXTUREACCESS_TARGET,
 		       	WINDOW_W, WINDOW_H);
 	SDL_SetRenderTarget(context, texture);
@@ -47,19 +45,34 @@ int main() {
 
 	SDL_Texture *background = createTiledTexture(context, "background.bmp");
 	SDL_Texture *foreground = createTiledTexture(context, "foreground.bmp");
+	SDL_SetTextureBlendMode(foreground, SDL_BLENDMODE_BLEND);
 
 	SDL_Surface *mask_surface = SDL_CreateRGBSurfaceWithFormat(0,
 		       	WINDOW_W, WINDOW_H, 32, SDL_PIXELFORMAT_RGBA8888);
 
 	SDL_LockSurface(mask_surface);
 	for (int i = 0; i < mask_surface->w * mask_surface->h; i++) {
-		((Uint32 *)mask_surface->pixels)[i] = 0x000000ff;
+		((Uint32 *)mask_surface->pixels)[i] = 0x00000000;
 	}
-	for (int i = 0; i < mask_surface->w * 50; i++) {
+	for (int i = mask_surface->w * 500; i < mask_surface->w * mask_surface->h; i++) {
 		((Uint32 *)mask_surface->pixels)[i] = 0xffffffff;
 	}
 	SDL_UnlockSurface(mask_surface);
-	SDL_Texture *terrain_texture = SDL_CreateTextureFromSurface(context, mask_surface);
+
+	SDL_Texture *terrain = SDL_CreateTextureFromSurface(context, mask_surface);
+
+	SDL_BlendMode true_mul = SDL_ComposeCustomBlendMode(
+			SDL_BLENDFACTOR_ZERO,
+		       	SDL_BLENDFACTOR_SRC_COLOR,
+		       	SDL_BLENDOPERATION_ADD,
+			SDL_BLENDFACTOR_ONE,
+		       	SDL_BLENDFACTOR_ZERO,
+		       	SDL_BLENDOPERATION_ADD);
+	SDL_SetTextureBlendMode(terrain, true_mul);
+
+	SDL_SetRenderTarget(context, foreground);
+	SDL_RenderCopy(context, terrain, 0, 0);
+	SDL_SetRenderTarget(context, 0);
 
 	int exit = 0;
 	while (!exit) {
@@ -70,10 +83,6 @@ int main() {
 			}
 		}
 		SDL_RenderCopy(context, background, 0, 0);
-		SDL_SetRenderTarget(context, foreground);
-		SDL_SetTextureBlendMode(terrain_texture, SDL_BLENDMODE_MUL);
-		SDL_RenderCopy(context, terrain_texture, 0, 0);
-		SDL_SetRenderTarget(context, 0);
 		SDL_RenderCopy(context, foreground, 0, 0);
 
 		SDL_RenderPresent(context);