Fix view/accessor offset and invariants; fix loading of Flight Helmet

4 files changed, 68 insertions, 66 deletions

diff --git a/src/asset/model.c b/src/asset/model.c
index a97d20e..b5c6b0d 100644
--- a/src/asset/model.c
+++ b/src/asset/model.c
@@ -1030,7 +1030,6 @@ static bool load_meshes(
         const cgltf_attribute*   attrib       = &prim->attributes[a];
         const cgltf_accessor*    accessor     = attrib->data;
         const cgltf_buffer_view* view         = accessor->buffer_view;
-        const cgltf_size         offset       = accessor->offset + view->offset;
         const cgltf_size         buffer_index = view->buffer - data->buffers;
 
         assert(buffer_index < data->buffers_count);
@@ -1120,12 +1119,20 @@ static bool load_meshes(
           break;
         }
 
-#define CONFIGURE_BUFFER(buf)         \
-  if (buf) {                          \
-    buf->buffer       = buffer;       \
-    buf->offset_bytes = offset;       \
-    buf->size_bytes   = view->size;   \
-    buf->stride_bytes = view->stride; \
+        // See comments here for accessor/view/buffer invariants:
+        //   https://github.com/KhronosGroup/glTF-Sample-Assets/issues/242
+        // Gfx only has Buffer and BufferView, not accessors. We must combine
+        // the glTF's accessor and view offsets correctly.
+        const cgltf_size offset     = accessor->offset + view->offset;
+        const cgltf_size size_bytes = view->size - accessor->offset;
+
+#define CONFIGURE_BUFFER(buf)            \
+  if (buf) {                             \
+    buf->buffer       = buffer;          \
+    buf->offset_bytes = offset;          \
+    buf->size_bytes   = size_bytes;      \
+    buf->stride_bytes = view->stride;    \
+    buf->count        = accessor->count; \
   }
         CONFIGURE_BUFFER(buffer_view_2d);
         CONFIGURE_BUFFER(buffer_view_3d);
@@ -1160,14 +1167,11 @@ static bool load_meshes(
       // either 2d or 3d positions but not both, here we can perform addition
       // to compute the total number of vertices.
       geometry_desc.num_verts =
-          (geometry_desc.positions2d.size_bytes / sizeof(vec2)) +
-          (geometry_desc.positions3d.size_bytes / sizeof(vec3));
-
-#define CHECK_COUNT(buffer_view, type, num_components)                 \
-  if (geometry_desc.buffer_view.buffer) {                              \
-    assert(                                                            \
-        (geometry_desc.buffer_view.size_bytes /                        \
-         (num_components * sizeof(type))) == geometry_desc.num_verts); \
+          geometry_desc.positions2d.count + geometry_desc.positions3d.count;
+
+#define CHECK_COUNT(buffer_view, type, num_components)                  \
+  if (geometry_desc.buffer_view.buffer) {                               \
+    assert(geometry_desc.buffer_view.count == geometry_desc.num_verts); \
   }
 
       // Check that the number of vertices is consistent across all vertex
diff --git a/src/core/geometry.c b/src/core/geometry.c
index cfc749f..488dc23 100644
--- a/src/core/geometry.c
+++ b/src/core/geometry.c
@@ -12,7 +12,7 @@
 ///
 /// Note that views are allowed to have no data, in which case a buffer of the
 /// specified size is created.
-#define view_is_populated(BUFFER_VIEW) (BUFFER_VIEW.size_bytes > 0)
+#define view_is_populated(BUFFER_VIEW) (BUFFER_VIEW.count > 0)
 
 static GLenum primitive_type_to_gl(PrimitiveType type) {
   switch (type) {
@@ -34,30 +34,25 @@ void init_view_buffer(
     BufferUsage buffer_usage) {
   if (!view->buffer) {
     view->buffer = gfx_make_buffer(
-        gfxcore,
-        &(BufferDesc){
-            .usage      = buffer_usage,
-            .type       = buffer_type,
-            .data.data  = view->data,
-            .data.count = view->size_bytes /
-                          gfx_get_buffer_type_size_bytes(buffer_type)});
+        gfxcore, &(BufferDesc){.usage      = buffer_usage,
+                               .type       = buffer_type,
+                               .data.data  = view->data,
+                               .data.count = view->count});
+    assert(view->buffer);
   }
-  assert(view->size_bytes <= view->buffer->size_bytes);
 }
 
-/// Configure the buffer in teh VAO.
+/// Configure the buffer in the VAO.
 static void configure_buffer(
     GfxCore* gfxcore, const GeometryDesc* desc, BufferView* view,
-    size_t num_components, size_t component_size_bytes, GLenum component_type,
-    GLboolean normalized, GLuint channel) {
+    size_t num_components, GLenum component_type, GLboolean normalized,
+    GLuint channel) {
   assert(gfxcore);
   assert(desc);
   assert(view);
   assert(view->buffer);
-  assert(
-      desc->num_verts <=
-      view->size_bytes / (num_components * component_size_bytes));
-  assert(view->size_bytes <= view->buffer->size_bytes);
+  assert(view->count == desc->num_verts);
+  assert((view->offset_bytes + view->size_bytes) <= view->buffer->size_bytes);
 
   glBindBuffer(GL_ARRAY_BUFFER, view->buffer->vbo);
   glEnableVertexAttribArray(channel);
@@ -89,8 +84,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->positions3d, 3, sizeof(float),
-        GL_FLOAT, GL_FALSE, GFX_POSITION_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->positions3d, 3, GL_FLOAT, GL_FALSE,
+        GFX_POSITION_CHANNEL);
   } else if (view_is_populated(desc->positions2d)) {
     init_view_buffer(
         gfxcore, (BufferView*)&desc->positions2d, Buffer2d, desc->buffer_usage);
@@ -98,8 +93,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->positions2d, 2, sizeof(float),
-        GL_FLOAT, GL_FALSE, GFX_POSITION_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->positions2d, 2, GL_FLOAT, GL_FALSE,
+        GFX_POSITION_CHANNEL);
   }
   if (view_is_populated(desc->normals)) {
     init_view_buffer(
@@ -108,8 +103,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->normals, 3, sizeof(float), GL_FLOAT,
-        GL_FALSE, GFX_NORMAL_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->normals, 3, GL_FLOAT, GL_FALSE,
+        GFX_NORMAL_CHANNEL);
   }
   if (view_is_populated(desc->tangents)) {
     init_view_buffer(
@@ -118,8 +113,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->tangents, 4, sizeof(float), GL_FLOAT,
-        GL_FALSE, GFX_TANGENT_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->tangents, 4, GL_FLOAT, GL_FALSE,
+        GFX_TANGENT_CHANNEL);
   }
   if (view_is_populated(desc->texcoords)) {
     init_view_buffer(
@@ -128,8 +123,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->texcoords, 2, sizeof(float),
-        GL_FLOAT, GL_FALSE, GFX_TEXCOORDS_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->texcoords, 2, GL_FLOAT, GL_FALSE,
+        GFX_TEXCOORDS_CHANNEL);
   }
   if (view_is_populated(desc->joints.u8)) {
     init_view_buffer(
@@ -138,8 +133,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->joints.u8, 4, sizeof(uint8_t),
-        GL_UNSIGNED_BYTE, GL_FALSE, GFX_JOINTS_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->joints.u8, 4, GL_UNSIGNED_BYTE,
+        GL_FALSE, GFX_JOINTS_CHANNEL);
   } else if (view_is_populated(desc->joints.u16)) {
     init_view_buffer(
         gfxcore, (BufferView*)&desc->joints.u16, BufferU16, desc->buffer_usage);
@@ -147,8 +142,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->joints.u16, 4, sizeof(uint16_t),
-        GL_UNSIGNED_SHORT, GL_FALSE, GFX_JOINTS_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->joints.u16, 4, GL_UNSIGNED_SHORT,
+        GL_FALSE, GFX_JOINTS_CHANNEL);
   }
 
   // If weights are given as unsigned integers, then they are normalized
@@ -160,8 +155,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->weights.u8, 4, sizeof(uint8_t),
-        GL_UNSIGNED_BYTE, GL_TRUE, GFX_WEIGHTS_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->weights.u8, 4, GL_UNSIGNED_BYTE,
+        GL_TRUE, GFX_WEIGHTS_CHANNEL);
   } else if (view_is_populated(desc->weights.u16)) {
     init_view_buffer(
         gfxcore, (BufferView*)&desc->weights.u16, BufferU16,
@@ -170,8 +165,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->weights.u16, 4, sizeof(uint16_t),
-        GL_UNSIGNED_SHORT, GL_TRUE, GFX_WEIGHTS_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->weights.u16, 4, GL_UNSIGNED_SHORT,
+        GL_TRUE, GFX_WEIGHTS_CHANNEL);
   } else if (view_is_populated(desc->weights.floats)) {
     init_view_buffer(
         gfxcore, (BufferView*)&desc->weights.floats, BufferFloat,
@@ -180,8 +175,8 @@ static bool configure_vertex_attributes(GfxCore* gfxcore, GeometryDesc* desc) {
       return false;
     }
     configure_buffer(
-        gfxcore, desc, (BufferView*)&desc->weights.floats, 4, sizeof(float),
-        GL_FLOAT, GL_FALSE, GFX_WEIGHTS_CHANNEL);
+        gfxcore, desc, (BufferView*)&desc->weights.floats, 4, GL_FLOAT,
+        GL_FALSE, GFX_WEIGHTS_CHANNEL);
   }
 
   return true;
@@ -282,9 +277,9 @@ void gfx_update_geometry(Geometry* geometry, const GeometryDesc* desc) {
     assert(geometry->desc.positions3d.buffer);
     gfx_update_buffer(
         geometry->desc.positions3d.buffer,
-        &(BufferDataDesc){
-            .vec3s = desc->positions3d.data,
-            .count = desc->positions3d.size_bytes / sizeof(vec3)});
+        &(BufferDataDesc){.vec3s = desc->positions3d.data,
+                          .count =
+                              desc->positions3d.size_bytes / sizeof(vec3)});
   }
   // TODO: more
   else {
diff --git a/src/render/imm.c b/src/render/imm.c
index 8a93488..7ab8d62 100644
--- a/src/render/imm.c
+++ b/src/render/imm.c
@@ -21,12 +21,14 @@ bool gfx_imm_make(Imm* renderer, GfxCore* gfxcore, LLR* llr) {
   renderer->llr     = llr;
 
   renderer->triangles = gfx_make_geometry(
-      gfxcore,
-      &(GeometryDesc){.type         = Triangles,
-                      .buffer_usage = BufferDynamic,
-                      .num_verts    = num_triangle_verts,
-                      .positions3d  = (BufferView3d){
-                           .size_bytes = num_triangle_verts * sizeof(vec3)}});
+      gfxcore, &(GeometryDesc){
+                   .type         = Triangles,
+                   .buffer_usage = BufferDynamic,
+                   .num_verts    = num_triangle_verts,
+                   .positions3d  = (BufferView3d){
+                                                  .size_bytes = num_triangle_verts * sizeof(vec3),
+                                                  .count      = num_triangle_verts}
+  });
   if (!renderer->triangles) {
     goto cleanup;
   }
diff --git a/src/util/geometry.c b/src/util/geometry.c
index afe0109..2ea0c82 100644
--- a/src/util/geometry.c
+++ b/src/util/geometry.c
@@ -17,12 +17,13 @@ static void make_quad_01_positions(vec2 positions[4]) {
 }
 
 static GeometryDesc make_quad_desc(vec2 positions[4]) {
-  GeometryDesc desc           = (GeometryDesc){0};
-  desc.positions2d.data       = positions;
-  desc.positions2d.size_bytes = 4 * sizeof(vec2);
-  desc.num_verts              = 4;
-  desc.type                   = TriangleStrip;
-  return desc;
+  return (GeometryDesc){
+      .positions2d = (BufferView2d){.data       = positions,
+                                    .size_bytes = 4 * sizeof(vec2),
+                                    .count      = 4},
+      .num_verts   = 4,
+      .type        = TriangleStrip
+  };
 }
 
 Geometry* gfx_make_quad_11(GfxCore* gfxcore) {