medfall

commit d9c28ef94d7e461160bd779c1397752ed49badaf
parent 06b85354b1b78110074af3fbb429da1d0cdbf712
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Sun Jan  8 19:57:32 +0200

Add BC4 support to the renderer

Diffstat:
renderer.cc
 | 
56
++++++++++++++++++++++++++++++++++++++++++++++++++++++--
renderer.h
 | 
3
+++
2 files changed, 57 insertions(+), 2 deletions(-)
diff --git a/renderer.cc b/renderer.cc
@@ -49,6 +49,7 @@ static GLenum textureformat_to_glenum( TextureFormat format ) {
 		case TEXFMT_RGB_FLOAT: return GL_RGB32F;
 		case TEXFMT_R_FLOAT: return GL_R32F;
 		case TEXFMT_R_U8: return GL_R8;
+		case TEXFMT_BC4: return GL_COMPRESSED_RED_RGTC1;
 	}
 
 	FATAL( "unsupported TextureFormat: %d", format );
@@ -261,6 +262,47 @@ void renderer_delete_shader( Shader shader ) {
 	glDeleteProgram( shader );
 }
 
+static bool is_compressed( TextureFormat format ) {
+	return format == TEXFMT_BC4;
+}
+
+static int mipmap_levels( u32 width, u32 height ) {
+	int levels = 1;
+	while( width > 1 || height > 1 ) {
+		levels++;
+		width = max( width / 2, u32( 1 ) );
+		height = max( height / 2, u32( 1 ) );
+	}
+	return levels;
+}
+
+static u32 texture_byte_size( u32 width, u32 height, TextureFormat format, bool mipmaps ) {
+	u32 total_dim = width * height;
+	if( mipmaps ) {
+		for( int i = 1; i < mipmap_levels( width, height ); i++ ) {
+			width = max( width / 2, u32( 1 ) );
+			height = max( height / 2, u32( 1 ) );
+			total_dim += width * height;
+		}
+	}
+
+	switch( format ) {
+		case TEXFMT_RGBA_FLOAT:
+			return total_dim * 4 * sizeof( float );
+		case TEXFMT_RGB_FLOAT:
+			return total_dim * 3 * sizeof( float );
+		case TEXFMT_R_FLOAT:
+			return total_dim * 1 * sizeof( float );
+		case TEXFMT_R_U8:
+			return total_dim * 1 * sizeof( u8 );
+		case TEXFMT_BC4:
+			return total_dim / 2;
+	}
+
+	FATAL( "unsupported TextureFormat: %d", format );
+	return 0;
+}
+
 Texture renderer_new_texture( TextureConfig config ) {
 	GLuint texture;
 	glGenTextures( 1, &texture );
@@ -294,13 +336,23 @@ Texture renderer_new_texture( TextureConfig config ) {
 			type = GL_UNSIGNED_BYTE;
 			break;
 
+		case TEXFMT_BC4:
+			break;
+
 		default:
 			FATAL( "unsupported TextureFormat: %d", config.format );
 			break;
 	}
 
-	glTexImage2D( GL_TEXTURE_2D, 0, internal_format,
-		config.width, config.height, 0, channels, type, config.data );
+	if( is_compressed( config.format ) ) {
+		u32 dxt_size = texture_byte_size( config.width, config.height, TEXFMT_BC4, false );
+		glCompressedTexImage2D( GL_TEXTURE_2D, 0, internal_format,
+			config.width, config.height, 0, dxt_size, config.data );
+	}
+	else {
+		glTexImage2D( GL_TEXTURE_2D, 0, internal_format,
+			config.width, config.height, 0, channels, type, config.data );
+	}
 
 	return texture;
 }
diff --git a/renderer.h b/renderer.h
@@ -135,14 +135,17 @@ enum TextureFormat {
 	TEXFMT_RGB_FLOAT,
 	TEXFMT_R_FLOAT,
 	TEXFMT_R_U8,
+	TEXFMT_BC4,
 };
 
 struct TextureConfig {
 	u32 width = 0;
 	u32 height = 0;
 	TextureFormat format = TEXFMT_RGBA_FLOAT;
+	bool srgb = false;
 	const void * data = NULL;
 	size_t data_size;
+	// TODO: internal format?
 	// TODO: min/mag filters, wrap modes, border
 };