1 files changed, 55 insertions, 20 deletions

diff --git a/main.c b/main.c
index c5c60af..646d79b 100644
--- a/main.c
+++ b/main.c
@@ -5,6 +5,15 @@
 #define WINDOW_W 1280
 #define WINDOW_H 720
 
+void renderMaskedTexture(SDL_Renderer *context, SDL_Texture *result, SDL_Texture *mask, SDL_Texture *diffuse) {
+	SDL_SetRenderTarget(context, result);
+	SDL_SetRenderDrawColor(context, 0, 0, 0, 0);
+	SDL_RenderClear(context);
+	SDL_RenderCopy(context, mask, 0, 0);
+	SDL_RenderCopy(context, diffuse, 0, 0);
+	SDL_SetRenderTarget(context, 0);
+}
+
 SDL_Texture *createTiledTexture(SDL_Renderer *context, const char *filename) {
 	SDL_Surface *texture_surface = SDL_LoadBMP(filename);
 	SDL_Texture *texture_tile = SDL_CreateTextureFromSurface(context, texture_surface);
@@ -14,7 +23,7 @@ SDL_Texture *createTiledTexture(SDL_Renderer *context, const char *filename) {
 
 	SDL_Texture *texture = SDL_CreateTexture(context,
 			SDL_PIXELFORMAT_RGBA8888,
-			SDL_TEXTUREACCESS_STATIC | SDL_TEXTUREACCESS_TARGET,
+			SDL_TEXTUREACCESS_TARGET,
 			WINDOW_W, WINDOW_H);
 	SDL_SetRenderTarget(context, texture);
 	for (int y = 0; y < WINDOW_H; y += tile_h) {
@@ -40,16 +49,20 @@ int main() {
 
 	SDL_Renderer *context = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
 
-	SDL_SetRenderDrawColor(context, 40, 40, 40, 255);
-	SDL_RenderClear(context);
-
 	SDL_Texture *background = createTiledTexture(context, "background.bmp");
+
 	SDL_Texture *foreground = createTiledTexture(context, "foreground.bmp");
-	SDL_SetTextureBlendMode(foreground, SDL_BLENDMODE_BLEND);
+	SDL_SetTextureBlendMode(foreground, SDL_BLENDMODE_MOD);
 
 	SDL_Surface *mask_surface = SDL_CreateRGBSurfaceWithFormat(0,
 			WINDOW_W, WINDOW_H, 32, SDL_PIXELFORMAT_RGBA8888);
 
+	SDL_Texture *terrain = SDL_CreateTexture(context,
+			SDL_PIXELFORMAT_RGBA8888,
+			SDL_TEXTUREACCESS_TARGET,
+			WINDOW_W, WINDOW_H);
+	SDL_SetTextureBlendMode(terrain, SDL_BLENDMODE_BLEND);
+
 	SDL_LockSurface(mask_surface);
 	for (int i = 0; i < mask_surface->w * mask_surface->h; i++) {
 		((Uint32 *)mask_surface->pixels)[i] = 0x00000000;
@@ -58,21 +71,9 @@ int main() {
 		((Uint32 *)mask_surface->pixels)[i] = 0xffffffff;
 	}
 	SDL_UnlockSurface(mask_surface);
+	SDL_Texture *mask_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);
+	renderMaskedTexture(context, terrain, mask_texture, foreground);
 
 	int exit = 0;
 	while (!exit) {
@@ -82,8 +83,42 @@ int main() {
 				exit = 1;
 			}
 		}
+		int mouse_x, mouse_y;
+		Uint32 mouse_state = SDL_GetMouseState(&mouse_x, &mouse_y);
+		if (mouse_state & SDL_BUTTON_LMASK) {
+			SDL_LockSurface(mask_surface);
+			unsigned size = 100;
+			for (int j = mouse_y - size / 2; j < mouse_y + size / 2; j++) {
+				for (int i = mouse_x - size / 2; i < mouse_x + size / 2; i++) {
+					size_t index = i + j * WINDOW_W;
+					((Uint32 *)mask_surface->pixels)[index] = 0xffffffff;
+				}
+			}
+			SDL_UnlockSurface(mask_surface);
+			SDL_DestroyTexture(mask_texture);
+			mask_texture = SDL_CreateTextureFromSurface(context, mask_surface);
+
+			renderMaskedTexture(context, terrain, mask_texture, foreground);
+		} else if (mouse_state & SDL_BUTTON_RMASK) {
+			SDL_LockSurface(mask_surface);
+			unsigned size = 100;
+			for (int j = mouse_y - size / 2; j < mouse_y + size / 2; j++) {
+				for (int i = mouse_x - size / 2; i < mouse_x + size / 2; i++) {
+					size_t index = i + j * WINDOW_W;
+					((Uint32 *)mask_surface->pixels)[index] = 0x00000000;
+				}
+			}
+			SDL_UnlockSurface(mask_surface);
+			SDL_DestroyTexture(mask_texture);
+			mask_texture = SDL_CreateTextureFromSurface(context, mask_surface);
+
+			renderMaskedTexture(context, terrain, mask_texture, foreground);
+		}
+		SDL_SetRenderDrawColor(context, 40, 40, 40, 255);
+		SDL_RenderClear(context);
+
 		SDL_RenderCopy(context, background, 0, 0);
-		SDL_RenderCopy(context, foreground, 0, 0);
+		SDL_RenderCopy(context, terrain, 0, 0);
 
 		SDL_RenderPresent(context);
 		SDL_Delay(10);