Blend modes;

src/api/graphics.c

@@ -6,12 +6,14 @@
 #include "filesystem/filesystem.h"
 #include <math.h>
 
-map_int_t MeshAttributeTypes;
-map_int_t MeshDrawModes;
-map_int_t MeshUsages;
+map_int_t BlendAlphaModes;
+map_int_t BlendModes;
 map_int_t CompareModes;
 map_int_t DrawModes;
 map_int_t FilterModes;
+map_int_t MeshAttributeTypes;
+map_int_t MeshDrawModes;
+map_int_t MeshUsages;
 map_int_t PolygonWindings;
 map_int_t TextureProjections;
 map_int_t WrapModes;
@@ -71,21 +73,19 @@ int l_lovrGraphicsInit(lua_State* L) {
   luax_registertype(L, "Skybox", lovrSkybox);
   luax_registertype(L, "Texture", lovrTexture);
 
-  map_init(&MeshAttributeTypes);
-  map_set(&MeshAttributeTypes, "float", MESH_FLOAT);
-  map_set(&MeshAttributeTypes, "byte", MESH_BYTE);
-  map_set(&MeshAttributeTypes, "int", MESH_INT);
+  map_init(&BlendAlphaModes);
+  map_set(&BlendAlphaModes, "alphamultiply", BLEND_ALPHA_MULTIPLY);
+  map_set(&BlendAlphaModes, "premultiplied", BLEND_PREMULTIPLIED);
 
-  map_init(&MeshDrawModes);
-  map_set(&MeshDrawModes, "points", MESH_POINTS);
-  map_set(&MeshDrawModes, "strip", MESH_TRIANGLE_STRIP);
-  map_set(&MeshDrawModes, "triangles", MESH_TRIANGLES);
-  map_set(&MeshDrawModes, "fan", MESH_TRIANGLE_FAN);
-
-  map_init(&MeshUsages);
-  map_set(&MeshUsages, "static", MESH_STATIC);
-  map_set(&MeshUsages, "dynamic", MESH_DYNAMIC);
-  map_set(&MeshUsages, "stream", MESH_STREAM);
+  map_init(&BlendModes);
+  map_set(&BlendModes, "alpha", BLEND_ALPHA);
+  map_set(&BlendModes, "add", BLEND_ADD);
+  map_set(&BlendModes, "subtract", BLEND_SUBTRACT);
+  map_set(&BlendModes, "multiply", BLEND_MULTIPLY);
+  map_set(&BlendModes, "lighten", BLEND_LIGHTEN);
+  map_set(&BlendModes, "darken", BLEND_DARKEN);
+  map_set(&BlendModes, "screen", BLEND_SCREEN);
+  map_set(&BlendModes, "replace", BLEND_REPLACE);
 
   map_init(&DrawModes);
   map_set(&DrawModes, "fill", DRAW_MODE_FILL);
@@ -107,6 +107,22 @@ int l_lovrGraphicsInit(lua_State* L) {
   map_set(&FilterModes, "nearest", FILTER_NEAREST);
   map_set(&FilterModes, "linear", FILTER_LINEAR);
 
+  map_init(&MeshAttributeTypes);
+  map_set(&MeshAttributeTypes, "float", MESH_FLOAT);
+  map_set(&MeshAttributeTypes, "byte", MESH_BYTE);
+  map_set(&MeshAttributeTypes, "int", MESH_INT);
+
+  map_init(&MeshDrawModes);
+  map_set(&MeshDrawModes, "points", MESH_POINTS);
+  map_set(&MeshDrawModes, "strip", MESH_TRIANGLE_STRIP);
+  map_set(&MeshDrawModes, "triangles", MESH_TRIANGLES);
+  map_set(&MeshDrawModes, "fan", MESH_TRIANGLE_FAN);
+
+  map_init(&MeshUsages);
+  map_set(&MeshUsages, "static", MESH_STATIC);
+  map_set(&MeshUsages, "dynamic", MESH_DYNAMIC);
+  map_set(&MeshUsages, "stream", MESH_STREAM);
+
   map_init(&WrapModes);
   map_set(&WrapModes, "clamp", WRAP_CLAMP);
   map_set(&WrapModes, "repeat", WRAP_REPEAT);
@@ -162,6 +178,22 @@ int l_lovrGraphicsSetBackgroundColor(lua_State* L) {
   return 0;
 }
 
+int l_lovrGraphicsGetBlendMode(lua_State* L) {
+  BlendMode mode;
+  BlendAlphaMode alphaMode;
+  lovrGraphicsGetBlendMode(&mode, &alphaMode);
+  luax_pushenum(L, &BlendModes, mode);
+  luax_pushenum(L, &BlendAlphaModes, alphaMode);
+  return 2;
+}
+
+int l_lovrGraphicsSetBlendMode(lua_State* L) {
+  BlendMode mode = *(BlendMode*) luax_checkenum(L, 1, &BlendModes, "blend mode");
+  BlendAlphaMode alphaMode = *(BlendAlphaMode*) luax_optenum(L, 2, "alphamultiply", &BlendAlphaModes, "alpha blend mode");
+  lovrGraphicsSetBlendMode(mode, alphaMode);
+  return 0;
+}
+
 int l_lovrGraphicsGetColor(lua_State* L) {
   unsigned char r, g, b, a;
   lovrGraphicsGetColor(&r, &g, &b, &a);
@@ -711,6 +743,8 @@ const luaL_Reg lovrGraphics[] = {
   { "present", l_lovrGraphicsPresent },
   { "getBackgroundColor", l_lovrGraphicsGetBackgroundColor },
   { "setBackgroundColor", l_lovrGraphicsSetBackgroundColor },
+  { "getBlendMode", l_lovrGraphicsGetBlendMode },
+  { "setBlendMode", l_lovrGraphicsSetBlendMode },
   { "getColor", l_lovrGraphicsGetColor },
   { "setColor", l_lovrGraphicsSetColor },
   { "getColorMask", l_lovrGraphicsGetColorMask },

src/api/lovr.h

@@ -28,9 +28,8 @@ extern const luaL_Reg lovrTexture[];
 extern const luaL_Reg lovrTimer[];
 extern const luaL_Reg lovrTransform[];
 
-extern map_int_t MeshAttributeTypes;
-extern map_int_t MeshDrawModes;
-extern map_int_t MeshUsages;
+extern map_int_t BlendAlphaModes;
+extern map_int_t BlendModes;
 extern map_int_t CompareModes;
 extern map_int_t ControllerAxes;
 extern map_int_t ControllerButtons;
@@ -38,6 +37,9 @@ extern map_int_t DrawModes;
 extern map_int_t EventTypes;
 extern map_int_t FilterModes;
 extern map_int_t HeadsetEyes;
+extern map_int_t MeshAttributeTypes;
+extern map_int_t MeshDrawModes;
+extern map_int_t MeshUsages;
 extern map_int_t PolygonWindings;
 extern map_int_t TextureProjections;
 extern map_int_t TimeUnits;

src/graphics/graphics.c

@@ -117,6 +117,61 @@ void lovrGraphicsSetBackgroundColor(float r, float g, float b, float a) {
   glClearColor(r / 255, g / 255, b / 255, a / 255);
 }
 
+void lovrGraphicsGetBlendMode(BlendMode* mode, BlendAlphaMode* alphaMode) {
+  *mode =  state.blendMode;
+  *alphaMode = state.blendAlphaMode;
+}
+
+void lovrGraphicsSetBlendMode(BlendMode mode, BlendAlphaMode alphaMode) {
+  GLenum srcRGB = mode == BLEND_MULTIPLY ? GL_DST_COLOR : GL_ONE;
+
+  if (srcRGB == GL_ONE && alphaMode == BLEND_ALPHA_MULTIPLY) {
+    srcRGB = GL_SRC_ALPHA;
+  }
+
+  switch (mode) {
+    case BLEND_ALPHA:
+      glBlendEquation(GL_FUNC_ADD);
+      glBlendFuncSeparate(srcRGB, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
+      break;
+
+    case BLEND_ADD:
+      glBlendEquation(GL_FUNC_ADD);
+      glBlendFuncSeparate(srcRGB, GL_ONE, GL_ZERO, GL_ONE);
+      break;
+
+    case BLEND_SUBTRACT:
+      glBlendEquation(GL_FUNC_REVERSE_SUBTRACT);
+      glBlendFuncSeparate(srcRGB, GL_ONE, GL_ZERO, GL_ONE);
+      break;
+
+    case BLEND_MULTIPLY:
+      glBlendEquation(GL_FUNC_ADD);
+      glBlendFuncSeparate(srcRGB, GL_ZERO, GL_DST_COLOR, GL_ZERO);
+      break;
+
+    case BLEND_LIGHTEN:
+      glBlendEquation(GL_MAX);
+      glBlendFuncSeparate(srcRGB, GL_ZERO, GL_ONE, GL_ZERO);
+      break;
+
+    case BLEND_DARKEN:
+      glBlendEquation(GL_MIN);
+      glBlendFuncSeparate(srcRGB, GL_ZERO, GL_ONE, GL_ZERO);
+      break;
+
+    case BLEND_SCREEN:
+      glBlendEquation(GL_FUNC_ADD);
+      glBlendFuncSeparate(srcRGB, GL_ONE_MINUS_SRC_COLOR, GL_ONE, GL_ONE_MINUS_SRC_COLOR);
+      break;
+
+    case BLEND_REPLACE:
+      glBlendEquation(GL_FUNC_ADD);
+      glBlendFuncSeparate(srcRGB, GL_ZERO, GL_ONE, GL_ZERO);
+      break;
+  }
+}
+
 void lovrGraphicsGetColor(unsigned char* r, unsigned char* g, unsigned char* b, unsigned char* a) {
   *r = LOVR_COLOR_R(state.color);
   *g = LOVR_COLOR_G(state.color);

src/graphics/graphics.h

@@ -11,6 +11,22 @@
 #define MAX_TRANSFORMS 64
 #define MAX_CANVASES 4
 
+typedef enum {
+  BLEND_ALPHA,
+  BLEND_ADD,
+  BLEND_SUBTRACT,
+  BLEND_MULTIPLY,
+  BLEND_LIGHTEN,
+  BLEND_DARKEN,
+  BLEND_SCREEN,
+  BLEND_REPLACE
+} BlendMode;
+
+typedef enum {
+  BLEND_ALPHA_MULTIPLY,
+  BLEND_PREMULTIPLIED
+} BlendAlphaMode;
+
 typedef enum {
   DRAW_MODE_FILL,
   DRAW_MODE_LINE
@@ -59,6 +75,8 @@ typedef struct {
   int canvas;
   unsigned int color;
   char colorMask;
+  BlendMode blendMode;
+  BlendAlphaMode blendAlphaMode;
   int isScissorEnabled;
   ScissorRectangle scissor;
   GLuint shapeArray;
@@ -85,6 +103,8 @@ void lovrGraphicsPrepare();
 // State
 void lovrGraphicsGetBackgroundColor(float* r, float* g, float* b, float* a);
 void lovrGraphicsSetBackgroundColor(float r, float g, float b, float a);
+void lovrGraphicsGetBlendMode(BlendMode* mode, BlendAlphaMode* alphaMode);
+void lovrGraphicsSetBlendMode(BlendMode mode, BlendAlphaMode alphaMode);
 void lovrGraphicsGetColor(unsigned char* r, unsigned char* g, unsigned char* b, unsigned char* a);
 void lovrGraphicsSetColor(unsigned char r, unsigned char g, unsigned char b, unsigned char a);
 void lovrGraphicsGetColorMask(char* r, char* g, char* b, char* a);