diff --git a/src/pc/gfx/gfx_vulkan.cpp b/src/pc/gfx/gfx_vulkan.cpp
index 2cb09d7..ac61f90 100644
--- a/src/pc/gfx/gfx_vulkan.cpp
+++ b/src/pc/gfx/gfx_vulkan.cpp
@@ -257,17 +257,6 @@ static std::pair<VkPipeline, VkPipelineLayout> gfx_vulkan_create_pipeline(const
         attributes.push_back(uv_attribute);
     }
 
-    if(needs_screenpos) {
-        VkVertexInputAttributeDescription screenpos_attribute = {};
-        screenpos_attribute.format = VK_FORMAT_R32G32B32A32_SFLOAT;
-        screenpos_attribute.location = current_location++;
-        screenpos_attribute.offset = num_floats * sizeof(float);
-
-        num_floats += 4;
-
-        attributes.push_back(screenpos_attribute);
-    }
-
     if(uses_fog) {
         VkVertexInputAttributeDescription fog_attribute = {};
         fog_attribute.format = VK_FORMAT_R32G32B32A32_SFLOAT;
@@ -281,11 +270,16 @@ static std::pair<VkPipeline, VkPipelineLayout> gfx_vulkan_create_pipeline(const
 
     for(int i = 0; i < features.num_inputs; i++) {
         VkVertexInputAttributeDescription extra_attribute = {};
-        extra_attribute.format = VK_FORMAT_R32G32B32A32_SFLOAT;
         extra_attribute.location = current_location++;
         extra_attribute.offset = num_floats * sizeof(float);
 
-        num_floats += 4;
+        if(uses_alpha) {
+            extra_attribute.format = VK_FORMAT_R32G32B32A32_SFLOAT;
+            num_floats += 4;
+        } else {
+            extra_attribute.format = VK_FORMAT_R32G32B32_SFLOAT;
+            num_floats += 3;
+        }
 
         attributes.push_back(extra_attribute);
     }
@@ -889,6 +883,8 @@ static void gfx_vulkan_renderer_on_resize(void) {
     // doesn't seem to be called?
 }
 
+static int buf_vbo_offset = 0;
+
 static void gfx_vulkan_renderer_start_frame(void) {
     vkWaitForFences(
         device, 1,
@@ -933,6 +929,8 @@ static void gfx_vulkan_renderer_start_frame(void) {
     render_pass_begin.renderArea.extent.height = 480;
 
     vkCmdBeginRenderPass(current_cmd, &render_pass_begin, VK_SUBPASS_CONTENTS_INLINE);
+
+    buf_vbo_offset = 0;
 }
 
 /* draw commands */
@@ -971,35 +969,34 @@ static void gfx_vulkan_renderer_unload_shader(struct ShaderProgram *old_prg) {
 static void gfx_vulkan_renderer_load_shader(struct ShaderProgram *new_prg) {
     ShaderProgramVulkan* vulkan = (ShaderProgramVulkan*)new_prg;
 
-    if(current_cmd != VK_NULL_HANDLE) {
-        vkCmdBindPipeline(current_cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, vulkan->pipeline);
-    }
-
     last_program = vulkan;
 }
 
 static void gfx_vulkan_renderer_draw_triangles(float buf_vbo[], size_t buf_vbo_len, size_t buf_vbo_num_tris) {
     if(last_program != nullptr) {
-        gfx_vulkan_renderer_load_shader(reinterpret_cast<ShaderProgram *>(last_program));
+        vkCmdBindPipeline(current_cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, last_program->pipeline);
     }
 
     void* mapped_data = nullptr;
-    vkMapMemory(device, vertex_memory, 0, buf_vbo_len, 0, &mapped_data);
+    vkMapMemory(device, vertex_memory, buf_vbo_offset, buf_vbo_len * sizeof(float), 0, &mapped_data);
 
     memcpy(mapped_data, buf_vbo, buf_vbo_len * sizeof(float));
 
     VkMappedMemoryRange range = {};
     range.sType = VK_STRUCTURE_TYPE_MAPPED_MEMORY_RANGE;
     range.memory = vertex_memory;
-    range.size = buf_vbo_len;
+    range.size = buf_vbo_len * sizeof(float);
+    range.offset = buf_vbo_offset;
     vkFlushMappedMemoryRanges(device, 1, &range);
 
     vkUnmapMemory(device, vertex_memory);
 
-    VkDeviceSize offsets[] = {0};
+    VkDeviceSize offsets[] = {static_cast<VkDeviceSize>(buf_vbo_offset)};
     vkCmdBindVertexBuffers(current_cmd, 0, 1, &vertex_buffer, offsets);
 
     vkCmdDraw(current_cmd, buf_vbo_num_tris * 3, 1, 0, 0);
+
+    buf_vbo_offset += buf_vbo_len * sizeof(float);
 }
 
 /* end draw commands */