beginnings of SDL support; minor fixes for SDL; raytrace web demo

1 files changed, 65 insertions, 0 deletions

diff --git a/src/library_sdl.js b/src/library_sdl.js
new file mode 100644
index 00000000..95842271
--- /dev/null
+++ b/src/library_sdl.js
@@ -0,0 +1,65 @@
+mergeInto(Library, {
+  SDL_Init: function(what) {
+    SDL_SURFACES = {};
+    return 1;
+  },
+
+  SDL_SetVideoMode: function(width, height, depth, flags, canvas) {
+  //                                                      ^^^^^^ a 'canvas' parameter is added here; supply a canvas from JS there
+    var surf = _malloc(14*QUANTUM_SIZE); // SDL_Surface has 14 fields of quantum size
+    SDL_SURFACES[surf] = {
+      width: width,
+      height: height,
+      canvas: canvas,
+      ctx: canvas.getContext('2d'),
+      surf: surf,
+    };
+    return surf;
+  },
+
+  SDL_Quit: function() {
+    return 1;
+  },
+
+  SDL_LockSurface: function(surf) {
+    var surfData = SDL_SURFACES[surf];
+    surfData.image = surfData.ctx.getImageData(0, 0, surfData.width, surfData.height);
+    // Copy pixel data to somewhere accessible to 'C/C++'
+    var num = surfData.image.data.length;
+    surfData.buffer = _malloc(num);
+    for (var i = 0; i < num; i++) {
+      HEAP[surfData.buffer+i] = surfData.image.data[i];
+    }
+    // Mark in C/C++-accessible SDL structure
+    // SDL_Surface has the following fields: Uint32 flags, SDL_PixelFormat *format; int w, h; Uint16 pitch; void *pixels; ...
+    // So we have fields all of the same size, and 5 of them before us.
+    HEAP[surf + 5*QUANTUM_SIZE] = surfData.buffer;
+  },
+
+  SDL_UnlockSurface: function(surf) {
+    var surfData = SDL_SURFACES[surf];
+    // Copy pixel data to image
+    var num = surfData.image.data.length;
+    for (var i = 0; i < num; i++) {
+      surfData.image.data[i] = HEAP[surfData.buffer+i];
+    }
+    for (var i = 0; i < num/4; i++) {
+      surfData.image.data[i*4+3] = 255; // opacity, as canvases blend alpha
+    }
+    // Copy to canvas
+    surfData.ctx.putImageData(surfData.image, 0, 0);
+    // Cleanup
+    surfData.image = null;
+    _free(surfData.buffer);
+    surfData.buffer = null;
+  },
+
+  SDL_Flip: function(surf) {
+    // We actually do this in Unlock...
+  },
+
+  SDL_Delay: function(delay) {
+    // No can do... unless you were a generator...
+  },
+});
+