From c5c7df6c91d3418a66838a6e6012b9ebc3bc77d9 Mon Sep 17 00:00:00 2001
From: cosmonaut <evan@moonside.games>
Date: Tue, 19 Jul 2022 17:27:56 -0700
Subject: [PATCH] power of two

---
 src/cram.c | 72 +++++++++++++++++++++++++++++++++---------------------
 1 file changed, 44 insertions(+), 28 deletions(-)

diff --git a/src/cram.c b/src/cram.c
index aa4a9e0..07169a9 100644
--- a/src/cram.c
+++ b/src/cram.c
@@ -106,34 +106,19 @@ typedef struct Cram_Internal_Context
 	Cram_AtlasData *atlasData;
 } Cram_Internal_Context;
 
-/* API functions */
+/* Internal functions */
 
-uint32_t Wellspring_LinkedVersion(void)
+/* https://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2 */
+static uint32_t Cram_Internal_NextPowerOfTwo(uint32_t v)
 {
-	return WELLSPRING_COMPILED_VERSION;
-}
-
-Cram_Context* Cram_Init(Cram_ContextCreateInfo *createInfo)
-{
-	Cram_Internal_Context *context = Cram_malloc(sizeof(Cram_Internal_Context));
-
-	context->name = Cram_strdup(createInfo->name);
-
-	context->width = createInfo->maxDimension;
-	context->height = createInfo->maxDimension;
-
-	context->padding = createInfo->padding;
-	context->trim = createInfo->trim;
-
-	context->images = Cram_malloc(INITIAL_DATA_CAPACITY * sizeof(Cram_Image));
-	context->imageCapacity = INITIAL_DATA_CAPACITY;
-	context->imageCount = 0;
-
-	context->atlasData = Cram_malloc(sizeof(Cram_AtlasData));
-
-	context->pixels = NULL;
-
-	return (Cram_Context*) context;
+	v--;
+	v |= v >> 1;
+	v |= v >> 2;
+	v |= v >> 4;
+	v |= v >> 8;
+	v |= v >> 16;
+	v++;
+	return v;
 }
 
 static uint8_t Cram_Internal_IsImageEqual(Cram_Image *a, Cram_Image *b)
@@ -220,6 +205,36 @@ static int8_t Cram_Internal_CopyPixels(
 	return 0;
 }
 
+/* API functions */
+
+uint32_t Wellspring_LinkedVersion(void)
+{
+	return WELLSPRING_COMPILED_VERSION;
+}
+
+Cram_Context* Cram_Init(Cram_ContextCreateInfo *createInfo)
+{
+	Cram_Internal_Context *context = Cram_malloc(sizeof(Cram_Internal_Context));
+
+	context->name = Cram_strdup(createInfo->name);
+
+	context->width = createInfo->maxDimension;
+	context->height = createInfo->maxDimension;
+
+	context->padding = createInfo->padding;
+	context->trim = createInfo->trim;
+
+	context->images = Cram_malloc(INITIAL_DATA_CAPACITY * sizeof(Cram_Image));
+	context->imageCapacity = INITIAL_DATA_CAPACITY;
+	context->imageCount = 0;
+
+	context->atlasData = Cram_malloc(sizeof(Cram_AtlasData));
+
+	context->pixels = NULL;
+
+	return (Cram_Context*) context;
+}
+
 void Cram_AddFile(Cram_Context *context, const char *path)
 {
 	Cram_Internal_Context *internalContext = (Cram_Internal_Context*) context;
@@ -378,6 +393,7 @@ int8_t Cram_Pack(Cram_Context *context)
 		}
 	}
 
+	/* TODO: replace this with something that uses MaxRects algorithm */
 	stbrp_pack_rects(&rectPackContext, rects, numRects);
 
 	numRects = 0;
@@ -404,8 +420,8 @@ int8_t Cram_Pack(Cram_Context *context)
 		}
 	}
 
-	internalContext->width = maxWidth;
-	internalContext->height = maxHeight;
+	internalContext->width = Cram_Internal_NextPowerOfTwo(maxWidth);
+	internalContext->height = Cram_Internal_NextPowerOfTwo(maxHeight);
 
 	internalContext->pixels = Cram_realloc(internalContext->pixels, internalContext->width * internalContext->height * 4);
 	Cram_memset(internalContext->pixels, 0, internalContext->width * internalContext->height * 4);