helper to get material effect from bind-material for given mesh primi…

…tive

include/ak/material.h

@@ -23,6 +23,11 @@ extern "C" {
 #include "common.h"
 #include "texture.h"
 
+struct AkBindMaterial;
+struct AkMeshPrimitive;
+struct AkEffect;
+struct AkInstanceMaterial;
+
 typedef enum AkGlMaterialType {
   AK_GL_MATERIAL_TYPE_EMISSION            = 1,
   AK_GL_MATERIAL_TYPE_AMBIENT             = 2,
@@ -122,6 +127,21 @@ typedef struct AkSpecularGlossiness {
   float               glossiness;
 } AkSpecularGlossiness;
 
+/*!
+ * @brief a helper that returns effect for given mesh prim for a bindMaterial
+ *
+ * @param bindMat      bind material object in AkNode
+ * @param meshPrim     mesh primitive
+ * @param foundInstMat instance material
+ *
+ * @return effect that points by a AkMaterial
+ */
+AK_EXPORT
+struct AkEffect*
+ak_effectForBindMaterial(struct AkBindMaterial      * __restrict bindMat,
+                         struct AkMeshPrimitive     * __restrict meshPrim,
+                         struct AkInstanceMaterial ** __restrict foundInstMat);
+
 #ifdef __cplusplus
 }
 #endif

include/ak/texture.h

@@ -82,7 +82,12 @@ typedef struct AkTexture {
 
 typedef struct AkTextureRef {
   struct AkTexture *texture;
-  const char       *texcoord; /* to bind texture to input coord dynamically */
+
+  /* to bind texture to input coord dynamically, e.g. used by bindMaterial in 
+     node like COLLADA  */
+  const char       *texcoord;
+
+  /* glTF like texture bind */
   const char       *coordInputName;
   int               slot;
 } AkTextureRef;

src/mat/mat.c

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2020 Recep Aslantas
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "../common.h"
+#include "../../include/ak/material.h"
+
+AK_EXPORT
+AkEffect*
+ak_effectForBindMaterial(AkBindMaterial      * __restrict bindMat,
+                         AkMeshPrimitive     * __restrict meshPrim,
+                         AkInstanceMaterial ** __restrict foundInstMat) {
+  AkMaterial         *material;
+  AkInstanceMaterial *materialInst;
+  AkGeometry         *geom;
+  AkMap              *materialMap;
+  AkMapItem          *mi;
+
+  if (!meshPrim || !meshPrim->mesh || !meshPrim->mesh->geom)
+    return NULL;
+
+  geom         = meshPrim->mesh->geom;
+  materialInst = bindMat->tcommon;
+  materialMap  = geom->materialMap;
+
+  while (materialInst) {
+    /* there is symbol, bind only to specified primitive */
+    if (materialInst->symbol) {
+      mi = ak_map_find(materialMap, (void *)materialInst->symbol);
+      while (mi) {
+        if ((AkMeshPrimitive *)mi->data == meshPrim) {
+          material = ak_instanceObject(&materialInst->base);
+          if (material && material->effect) {
+            *foundInstMat = materialInst;
+            return ak_instanceObject(&material->effect->base);
+          } else {
+            return NULL;
+          }
+        }
+        mi = mi->next;
+      }
+    }
+
+    /* bind to whole geometry, TODO: is this OK ? */
+    else {
+      material = ak_instanceObject(&materialInst->base);
+      if (material && material->effect) {
+        *foundInstMat = materialInst;
+        return ak_instanceObject(&material->effect->base);
+      } else {
+        return NULL;
+      }
+    }
+
+    materialInst = (AkInstanceMaterial *)materialInst->base.next;
+  }
+
+  return NULL;
+}