1 files changed, 199 insertions, 0 deletions

diff --git a/gfx-iso/src/backend.c b/gfx-iso/src/backend.c
new file mode 100644
index 0000000..db91647
--- /dev/null
+++ b/gfx-iso/src/backend.c
@@ -0,0 +1,199 @@
+#include <isogfx/backend.h>
+#include <isogfx/isogfx.h>
+
+#include <gfx/core.h>
+#include <gfx/gfx.h>
+#include <gfx/renderer.h>
+#include <gfx/scene.h>
+#include <gfx/util/geometry.h>
+#include <gfx/util/shader.h>
+
+#include <assert.h>
+#include <stdlib.h>
+
+typedef struct IsoBackend {
+  Gfx*   gfx;
+  Scene* scene;
+  /// The screen or "iso screen" refers to the colour buffer of the iso graphics
+  /// library. This texture is used to draw the iso screen onto the graphics
+  /// window.
+  Texture* screen_texture;
+  /// Window size.
+  int window_width;
+  int window_height;
+  /// The viewport refers to the area inside the window to which screen_texture
+  /// is drawn. It is a scaled version of the iso screen, scaled while
+  /// respecting the iso screen's aspect ratio to prevent distortion.
+  int    viewport_x, viewport_y, viewport_width, viewport_height;
+  double stretch; // Stretch factor from iso screen dimensions to viewport
+                  // dimensions.
+} IsoBackend;
+
+IsoBackend* IsoBackendInit(const IsoGfx* iso) {
+  assert(iso);
+
+  IsoBackend* backend = calloc(1, sizeof(IsoBackend));
+  if (!backend) {
+    return 0;
+  }
+
+  if (!(backend->gfx = gfx_init())) {
+    goto cleanup;
+  }
+  GfxCore* gfxcore = gfx_get_core(backend->gfx);
+
+  int screen_width, screen_height;
+  isogfx_get_screen_size(iso, &screen_width, &screen_height);
+
+  if (!(backend->screen_texture = gfx_make_texture(
+            gfxcore, &(TextureDesc){
+                         .width     = screen_width,
+                         .height    = screen_height,
+                         .dimension = Texture2D,
+                         .format    = TextureSRGBA8,
+                         .filtering = NearestFiltering,
+                         .wrap      = ClampToEdge,
+                         .mipmaps   = false}))) {
+    goto cleanup;
+  }
+
+  ShaderProgram* shader = gfx_make_view_texture_shader(gfxcore);
+  if (!shader) {
+    goto cleanup;
+  }
+
+  Geometry* geometry = gfx_make_quad_11(gfxcore);
+  if (!geometry) {
+    goto cleanup;
+  }
+
+  MaterialDesc material_desc = (MaterialDesc){.num_uniforms = 1};
+  material_desc.uniforms[0]  = (ShaderUniform){
+       .type          = UniformTexture,
+       .value.texture = backend->screen_texture,
+       .name          = sstring_make("Texture")};
+  Material* material = gfx_make_material(&material_desc);
+  if (!material) {
+    return false;
+  }
+
+  const MeshDesc mesh_desc =
+      (MeshDesc){.geometry = geometry, .material = material, .shader = shader};
+  Mesh* mesh = gfx_make_mesh(&mesh_desc);
+  if (!mesh) {
+    goto cleanup;
+  }
+
+  SceneObject* object =
+      gfx_make_object(&(ObjectDesc){.num_meshes = 1, .meshes = {mesh}});
+  if (!object) {
+    goto cleanup;
+  }
+
+  backend->scene  = gfx_make_scene();
+  SceneNode* node = gfx_make_object_node(object);
+  SceneNode* root = gfx_get_scene_root(backend->scene);
+  gfx_set_node_parent(node, root);
+
+  return backend;
+
+cleanup:
+  if (backend->gfx) {
+    gfx_destroy(&backend->gfx);
+  }
+  free(backend);
+  return 0;
+}
+
+void IsoBackendShutdown(IsoBackend** ppApp) {
+  assert(ppApp);
+
+  IsoBackend* app = *ppApp;
+  if (!app) {
+    return;
+  }
+
+  gfx_destroy(&app->gfx);
+}
+
+void IsoBackendResizeWindow(
+    IsoBackend* app, const IsoGfx* iso, int width, int height) {
+  assert(app);
+  assert(iso);
+
+  app->window_width  = width;
+  app->window_height = height;
+
+  // Virtual screen dimensions.
+  int screen_width, screen_height;
+  isogfx_get_screen_size(iso, &screen_width, &screen_height);
+
+  // Stretch the virtual screen onto the viewport while respecting the screen's
+  // aspect ratio to prevent distortion.
+  if (width > height) { // Wide screen.
+    app->stretch         = (double)height / (double)screen_height;
+    app->viewport_width  = (int)((double)screen_width * app->stretch);
+    app->viewport_height = height;
+    app->viewport_x      = (width - app->viewport_width) / 2;
+    app->viewport_y      = 0;
+  } else { // Tall screen.
+    app->stretch         = (double)width / (double)screen_width;
+    app->viewport_width  = width;
+    app->viewport_height = (int)((float)screen_height * app->stretch);
+    app->viewport_x      = 0;
+    app->viewport_y      = (height - app->viewport_height) / 2;
+  }
+}
+
+void IsoBackendRender(const IsoBackend* app, const IsoGfx* iso) {
+  assert(app);
+  assert(iso);
+
+  const Pixel* screen = isogfx_get_screen_buffer(iso);
+  assert(screen);
+  gfx_update_texture(app->screen_texture, &(TextureDataDesc){.pixels = screen});
+
+  GfxCore*  gfxcore  = gfx_get_core(app->gfx);
+  Renderer* renderer = gfx_get_renderer(app->gfx);
+
+  // Clear the whole window.
+  gfx_set_viewport(gfxcore, 0, 0, app->window_width, app->window_height);
+  gfx_clear(gfxcore, vec4_make(0, 0, 0, 0));
+
+  // Draw to the subregion where the virtual screen can stretch without
+  // distortion.
+  gfx_set_viewport(
+      gfxcore, app->viewport_x, app->viewport_y, app->viewport_width,
+      app->viewport_height);
+
+  // Render the iso screen.
+  gfx_start_frame(gfxcore);
+  gfx_render_scene(
+      renderer, &(RenderSceneParams){
+                    .mode = RenderDefault, .scene = app->scene, .camera = 0});
+  gfx_end_frame(gfxcore);
+}
+
+bool IsoBackendGetMousePosition(
+    const IsoBackend* app, double window_x, double window_y, double* x,
+    double* y) {
+  assert(app);
+
+  // Translate from window coordinates to the subregion where the stretched
+  // iso screen is rendered.
+  const double screen_x = window_x - app->viewport_x;
+  const double screen_y = window_y - app->viewport_y;
+
+  // Position may be out of bounds.
+  if ((0 <= screen_x) && (screen_x < app->viewport_width) && (0 <= screen_y) &&
+      (screen_y < app->viewport_height)) {
+    // Scale back from the stretched subregion to the iso screen dimensions.
+    *x = screen_x / app->stretch;
+    *y = screen_y / app->stretch;
+    return true;
+  } else {
+    *x = -1;
+    *y = -1;
+    return false;
+  }
+}