modifyChunk

libcygnet/include/cygnet/Renderer.h

@@ -38,6 +38,7 @@ public:
 
 	RenderChunk createChunk(
 			TileID tiles[SwanCommon::CHUNK_WIDTH * SwanCommon::CHUNK_HEIGHT]);
+	void modifyChunk(RenderChunk chunk, SwanCommon::Vec2i pos, TileID id);
 	void destroyChunk(RenderChunk chunk);
 
 private:

libcygnet/src/Renderer.cc

@@ -218,11 +218,13 @@ RenderChunk Renderer::createChunk(
 	RenderChunk chunk;
 	glGenTextures(1, &chunk.tex);
 	glCheck();
+	glActiveTexture(GL_TEXTURE0);
 	glBindTexture(GL_TEXTURE_2D, chunk.tex);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	glCheck();
 
 	static_assert(
 			std::endian::native == std::endian::big ||
@@ -254,6 +256,28 @@ RenderChunk Renderer::createChunk(
 	return chunk;
 }
 
+void Renderer::modifyChunk(RenderChunk chunk, SwanCommon::Vec2i pos, TileID id) {
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, chunk.tex);
+	glCheck();
+
+	static_assert(
+			std::endian::native == std::endian::big ||
+			std::endian::native == std::endian::little,
+			"Expected either big or little endian");
+
+	if constexpr (std::endian::native == std::endian::little) {
+		glTexSubImage2D(
+				GL_TEXTURE_2D, 0, pos.x, pos.y, 1, 1,
+				GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, &id);
+	} else if constexpr (std::endian::native == std::endian::big) {
+		uint8_t buf[] = { (uint8_t)(id & 0xff), (uint8_t)((id & 0xff00) >> 8) };
+		glTexSubImage2D(
+				GL_TEXTURE_2D, 0, pos.x, pos.y, 1, 1,
+				GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, buf);
+	}
+}
+
 void Renderer::destroyChunk(RenderChunk chunk) {
 	glDeleteTextures(1, &chunk.tex);
 }

src/cygnet-test.cc

@@ -46,6 +46,8 @@ int main() {
 		.zoom = 0.125,
 	};
 
+	unsigned int lol = 0;
+
 	while (true) {
 		SDL_Event evt;
 		while (SDL_PollEvent(&evt)) {
@@ -55,6 +57,11 @@ int main() {
 			}
 		}
 
+		lol += 1;
+		rnd.modifyChunk(chunk, {0, 0}, (lol / 20) % 6);
+		rnd.modifyChunk(chunk, {4, 4}, ((lol / 20) + 3) % 6);
+		rnd.modifyChunk(chunk, {3, 2}, ((lol / 25) + 7) % 6);
+
 		rnd.drawChunk({0, 0}, chunk);
 
 		win.clear();