android: renderer_opengl: Partially implement glLogicOp on GLES.

src/video_core/renderer_opengl/gl_rasterizer.cpp

@@ -948,6 +948,10 @@ void RasterizerOpenGL::NotifyPicaRegisterChanged(u32 id) {
 
     // Blending
     case PICA_REG_INDEX(framebuffer.output_merger.alphablend_enable):
+        if (GLES) {
+            // With GLES, we need this in the fragment shader to emulate logic operations
+            shader_dirty = true;
+        }
         SyncBlendEnabled();
         break;
     case PICA_REG_INDEX(framebuffer.output_merger.alpha_blending):
@@ -1068,6 +1072,10 @@ void RasterizerOpenGL::NotifyPicaRegisterChanged(u32 id) {
 
     // Logic op
     case PICA_REG_INDEX(framebuffer.output_merger.logic_op):
+        if (GLES) {
+            // With GLES, we need this in the fragment shader to emulate logic operations
+            shader_dirty = true;
+        }
         SyncLogicOp();
         break;
 
@@ -1822,11 +1830,31 @@ void RasterizerOpenGL::SyncAlphaTest() {
 }
 
 void RasterizerOpenGL::SyncLogicOp() {
-    state.logic_op = PicaToGL::LogicOp(Pica::g_state.regs.framebuffer.output_merger.logic_op);
+    const auto& regs = Pica::g_state.regs;
+    state.logic_op = PicaToGL::LogicOp(regs.framebuffer.output_merger.logic_op);
+
+    if (GLES) {
+        if (!regs.framebuffer.output_merger.alphablend_enable) {
+            if (regs.framebuffer.output_merger.logic_op == Pica::FramebufferRegs::LogicOp::NoOp) {
+                // Color output is disabled by logic operation. We use color write mask to skip
+                // color but allow depth write.
+                state.color_mask = {};
+            }
+        }
+    }
 }
 
 void RasterizerOpenGL::SyncColorWriteMask() {
     const auto& regs = Pica::g_state.regs;
+    if (GLES) {
+        if (!regs.framebuffer.output_merger.alphablend_enable) {
+            if (regs.framebuffer.output_merger.logic_op == Pica::FramebufferRegs::LogicOp::NoOp) {
+                // Color output is disabled by logic operation. We use color write mask to skip
+                // color but allow depth write. Return early to avoid overwriting this.
+                return;
+            }
+        }
+    }
 
     auto IsColorWriteEnabled = [&](u32 value) {
         return (regs.framebuffer.framebuffer.allow_color_write != 0 && value != 0) ? GL_TRUE

src/video_core/renderer_opengl/gl_shader_gen.cpp

@@ -127,6 +127,17 @@ PicaFSConfig PicaFSConfig::BuildFromRegs(const Pica::Regs& regs) {
 
     state.texture2_use_coord1 = regs.texturing.main_config.texture2_use_coord1 != 0;
 
+    if (GLES) {
+        // With GLES, we need this in the fragment shader to emulate logic operations
+        state.alphablend_enable =
+            Pica::g_state.regs.framebuffer.output_merger.alphablend_enable == 1;
+        state.logic_op = regs.framebuffer.output_merger.logic_op;
+    } else {
+        // We don't need these otherwise, reset them to avoid unnecessary shader generation
+        state.alphablend_enable = {};
+        state.logic_op = {};
+    }
+
     // Copy relevant tev stages fields.
     // We don't sync const_color here because of the high variance, it is a
     // shader uniform instead.
@@ -1568,6 +1579,32 @@ do {
         out += "color = byteround(last_tex_env_out);\n";
     }
 
+    if (GLES) {
+        if (!state.alphablend_enable) {
+            switch (state.logic_op) {
+            case FramebufferRegs::LogicOp::Clear:
+                out += "color = vec4(0);\n";
+                break;
+            case FramebufferRegs::LogicOp::Set:
+                out += "color = vec4(1);\n";
+                break;
+            case FramebufferRegs::LogicOp::Copy:
+                // Take the color output as-is
+                break;
+            case FramebufferRegs::LogicOp::CopyInverted:
+                out += "color = ~color;\n";
+                break;
+            case FramebufferRegs::LogicOp::NoOp:
+                // We need to discard the color, but not necessarily the depth. This is not possible
+                // with fragment shader alone, so we emulate this behavior on GLES with glColorMask.
+                break;
+            default:
+                LOG_CRITICAL(HW_GPU, "Unhandled logic_op {:x}", static_cast<int>(state.logic_op));
+                UNIMPLEMENTED();
+            }
+        }
+    }
+
     out += '}';
 
     return {std::move(out)};

src/video_core/renderer_opengl/gl_shader_gen.h

@@ -61,6 +61,8 @@ struct PicaFSConfigState {
     Pica::RasterizerRegs::DepthBuffering depthmap_enable;
     Pica::TexturingRegs::FogMode fog_mode;
     bool fog_flip;
+    bool alphablend_enable;
+    Pica::FramebufferRegs::LogicOp logic_op;
 
     struct {
         struct {

src/video_core/renderer_opengl/gl_state.cpp

@@ -170,10 +170,17 @@ void OpenGLState::Apply() const {
     if (blend.enabled != cur_state.blend.enabled) {
         if (blend.enabled) {
             glEnable(GL_BLEND);
-            glDisable(GL_COLOR_LOGIC_OP);
         } else {
             glDisable(GL_BLEND);
-            glEnable(GL_COLOR_LOGIC_OP);
+        }
+
+        // GLES does not support glLogicOp
+        if (!GLES) {
+            if (blend.enabled) {
+                glDisable(GL_COLOR_LOGIC_OP);
+            } else {
+                glEnable(GL_COLOR_LOGIC_OP);
+            }
         }
     }
 
@@ -197,13 +204,11 @@ void OpenGLState::Apply() const {
         glBlendEquationSeparate(blend.rgb_equation, blend.a_equation);
     }
 
-    // GLES3 does not support glLogicOp
+    // GLES does not support glLogicOp
     if (!GLES) {
         if (logic_op != cur_state.logic_op) {
             glLogicOp(logic_op);
         }
-    } else {
-        LOG_TRACE(Render_OpenGL, "glLogicOps are unimplemented...");
     }
 
     // Textures