Betweenlands fix (#1894)

glsm/src/main/java/com/gtnewhorizons/angelica/glsm/CompatShaderTransformer.java

@@ -1,5 +1,10 @@
 package com.gtnewhorizons.angelica.glsm;
 
+import com.gtnewhorizon.gtnhlib.client.renderer.vertex.VertexFormatElement.Usage;
+import org.antlr.v4.runtime.tree.ParseTree;
+import org.antlr.v4.runtime.tree.TerminalNode;
+import org.taumc.glsl.grammar.GLSLLexer;
+import org.taumc.glsl.grammar.GLSLParser;
 import org.taumc.glsl.ShaderParser;
 import org.taumc.glsl.Transformer;
 
@@ -8,9 +13,11 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -182,8 +189,9 @@ public class CompatShaderTransformer {
             transformer.rename("gl_FrontColor", "angelica_FrontColor");
             transformer.prependMain("angelica_FrontColor = vec4(1.0);");
 
-            // Vertex attributes — replaces removed FFP vertex inputs with explicit in declarations
-            transformVertexAttributes(transformer, source);
+            final FFPInputs ffp = FFPInputs.detect(source);
+            assignVertexInputLocations(transformer, ffp);
+            transformVertexAttributes(transformer, source, ffp);
         } else {
             if (source.contains("gl_Color")) {
                 transformer.injectVariable("in vec4 angelica_FrontColor;");
@@ -310,25 +318,25 @@ public class CompatShaderTransformer {
     /**
      * Replace removed FFP vertex attributes with explicit {@code in} declarations at core profile attribute locations.
      */
-    private static void transformVertexAttributes(Transformer transformer, String source) {
-        if (source.contains("gl_Vertex") || source.contains("ftransform")) {
+    private static void transformVertexAttributes(Transformer transformer, String source, FFPInputs ffp) {
+        if (ffp.position()) {
             transformer.injectVariable("layout(location = 0) in vec4 angelica_Vertex;");
             transformer.rename("gl_Vertex", "angelica_Vertex");
         }
         // gl_Color in vertex shaders is the per-vertex color attribute, distinct from the fragment gl_Color (interpolated gl_FrontColor) handled above
-        if (source.contains("gl_Color")) {
+        if (ffp.color()) {
             transformer.injectVariable("layout(location = 1) in vec4 angelica_Color;");
             transformer.rename("gl_Color", "angelica_Color");
         }
-        if (source.contains("gl_MultiTexCoord0")) {
+        if (ffp.uv0()) {
             transformer.injectVariable("layout(location = 2) in vec4 angelica_MultiTexCoord0;");
             transformer.rename("gl_MultiTexCoord0", "angelica_MultiTexCoord0");
         }
-        if (source.contains("gl_MultiTexCoord1")) {
+        if (ffp.uv1()) {
             transformer.injectVariable("layout(location = 3) in vec4 angelica_MultiTexCoord1;");
             transformer.rename("gl_MultiTexCoord1", "angelica_MultiTexCoord1");
         }
-        if (source.contains("gl_Normal")) {
+        if (ffp.normal()) {
             transformer.injectVariable("layout(location = 4) in vec3 angelica_Normal;");
             transformer.rename("gl_Normal", "angelica_Normal");
         }
@@ -337,6 +345,145 @@ public class CompatShaderTransformer {
         }
     }
 
+    private static final int MAX_VERTEX_ATTRIBS = 16;
+
+    private record FFPInputs(boolean position, boolean color, boolean uv0, boolean uv1, boolean normal) {
+        static FFPInputs detect(String source) {
+            return new FFPInputs(
+                source.contains("gl_Vertex") || source.contains("ftransform"),
+                source.contains("gl_Color"),
+                source.contains("gl_MultiTexCoord0"),
+                source.contains("gl_MultiTexCoord1"),
+                source.contains("gl_Normal"));
+        }
+    }
+
+    /** Adaptation of Mesa's assign_attribute_or_color_locations */
+    private static void assignVertexInputLocations(Transformer transformer, FFPInputs ffp) {
+        int used = 0;
+        if (ffp.position()) used |= 1 << Usage.POSITION.getAttributeLocation();
+        if (ffp.color()) used |= 1 << Usage.COLOR.getAttributeLocation();
+        if (ffp.uv0()) used |= 1 << Usage.PRIMARY_UV.getAttributeLocation();
+        if (ffp.uv1()) used |= 1 << Usage.SECONDARY_UV.getAttributeLocation();
+        if (ffp.normal()) used |= 1 << Usage.NORMAL.getAttributeLocation();
+
+        record Input(String name, String baseType, String arraySuffix, int slots, int index) {}
+        final List<Input> toAssign = new ArrayList<>();
+        int index = 0;
+
+        for (TerminalNode storage : transformer.collectStorage()) {
+            final int tokenType = storage.getSymbol().getType();
+            if (tokenType != GLSLLexer.ATTRIBUTE && tokenType != GLSLLexer.IN) continue;
+
+            ParseTree node = storage.getParent();
+            while (node != null && !(node instanceof GLSLParser.Single_declarationContext)) {
+                node = node.getParent();
+            }
+            if (!(node instanceof GLSLParser.Single_declarationContext decl)) continue;
+            if (decl.typeless_declaration() == null) continue;
+
+            final GLSLParser.Type_specifierContext typeSpec = decl.fully_specified_type().type_specifier();
+            final String baseType = GlslTransformUtils.getFormattedShader(typeSpec.type_specifier_nonarray(), "").trim();
+            final int typeArraySlots = arraySlots(typeSpec.array_specifier());
+            final String typeArray = arraySuffix(typeSpec.array_specifier());
+
+            if (hasLayoutQualifier(decl)) {
+                final int loc = explicitLocation(decl);
+                final int slots = baseSlots(baseType) * typeArraySlots * arraySlots(decl.typeless_declaration().array_specifier());
+                if (loc >= 0) used |= slotMask(slots) << loc;
+                continue;
+            }
+
+            final List<GLSLParser.Typeless_declarationContext> declarators = new ArrayList<>();
+            declarators.add(decl.typeless_declaration());
+            if (decl.getParent() instanceof GLSLParser.Init_declarator_listContext list) {
+                declarators.addAll(list.typeless_declaration());
+            }
+            for (GLSLParser.Typeless_declarationContext d : declarators) {
+                if (d.IDENTIFIER() == null) continue;
+                final int slots = baseSlots(baseType) * typeArraySlots * arraySlots(d.array_specifier());
+                final String arraySuffix = typeArray + arraySuffix(d.array_specifier());
+                toAssign.add(new Input(d.IDENTIFIER().getText(), baseType, arraySuffix, slots, index++));
+            }
+        }
+
+        toAssign.sort((a, b) -> a.slots() != b.slots() ? b.slots() - a.slots() : a.index() - b.index());
+
+        for (Input in : toAssign) {
+            final int loc = findAvailableSlots(used, in.slots());
+            if (loc < 0) continue;
+            used |= slotMask(in.slots()) << loc;
+            transformer.removeVariable(in.name());
+            transformer.variable = null;
+            transformer.injectVariable("layout(location = " + loc + ") in " + in.baseType() + " " + in.name() + in.arraySuffix() + ";");
+        }
+    }
+
+    private static String arraySuffix(GLSLParser.Array_specifierContext arraySpec) {
+        return arraySpec != null ? GlslTransformUtils.getFormattedShader(arraySpec, "").trim() : "";
+    }
+
+    private static int arraySlots(GLSLParser.Array_specifierContext arraySpec) {
+        if (arraySpec == null) return 1;
+        int product = 1;
+        for (GLSLParser.DimensionContext dim : arraySpec.dimension()) {
+            if (dim.constant_expression() == null) continue;
+            try {
+                product *= Integer.decode(GlslTransformUtils.getFormattedShader(dim.constant_expression(), "").trim());
+            } catch (NumberFormatException ignored) {}
+        }
+        return product;
+    }
+
+    private static int baseSlots(String type) {
+        final String dims = type.startsWith("dmat") ? type.substring(4) : type.startsWith("mat") ? type.substring(3) : null;
+        if (dims != null && !dims.isEmpty() && Character.isDigit(dims.charAt(0))) {
+            return dims.charAt(0) - '0';
+        }
+        return 1;
+    }
+
+    private static int slotMask(int slots) {
+        return (slots >= 32) ? -1 : (1 << slots) - 1;
+    }
+
+    private static int findAvailableSlots(int used, int needed) {
+        if (needed <= 0) return -1;
+        final int mask = slotMask(needed);
+        for (int i = 0; i <= MAX_VERTEX_ATTRIBS - needed; i++) {
+            if (((mask << i) & ~used) == (mask << i)) return i;
+        }
+        return -1;
+    }
+
+    private static int explicitLocation(GLSLParser.Single_declarationContext decl) {
+        final GLSLParser.Type_qualifierContext qualifier = decl.fully_specified_type().type_qualifier();
+        if (qualifier == null) return -1;
+        for (GLSLParser.Single_type_qualifierContext single : qualifier.single_type_qualifier()) {
+            final GLSLParser.Layout_qualifierContext layout = single.layout_qualifier();
+            if (layout == null) continue;
+            for (GLSLParser.Layout_qualifier_idContext id : layout.layout_qualifier_id_list().layout_qualifier_id()) {
+                if (id.IDENTIFIER() != null && "location".equals(id.IDENTIFIER().getText()) && id.constant_expression() != null) {
+                    try {
+                        return Integer.decode(GlslTransformUtils.getFormattedShader(id.constant_expression(), "").trim());
+                    } catch (NumberFormatException ignored) {
+                        return -1;
+                    }
+                }
+            }
+        }
+        return -1;
+    }
+
+    private static boolean hasLayoutQualifier(GLSLParser.Single_declarationContext decl) {
+        final GLSLParser.Type_qualifierContext qualifier = decl.fully_specified_type().type_qualifier();
+        if (qualifier == null) return false;
+        for (GLSLParser.Single_type_qualifierContext single : qualifier.single_type_qualifier()) {
+            if (single.layout_qualifier() != null) return true;
+        }
+        return false;
+    }
+
     private static void dumpShader(String original, String transformed, boolean isFragment, boolean wasTransformed) {
         if (DUMP_DIR == null) return;
         final int id = dumpCounter.getAndIncrement();

glsm/src/main/java/com/gtnewhorizons/angelica/glsm/GLStateManager.java

@@ -5792,6 +5792,9 @@ public class GLStateManager {
             generateVertexShaderIfNeeded(program);
         }
         RENDER_BACKEND.linkProgram(program);
+        if (ShaderManager.getInstance().isEnabled() && RENDER_BACKEND.getProgrami(program, GL20.GL_LINK_STATUS) == GL11.GL_FALSE) {
+            LOGGER.warn("Program {} failed to link: {}", program, RENDER_BACKEND.getProgramInfoLog(program));
+        }
         CompatUniformManager.onLinkProgram(program);
     }
 

glsm/src/main/java/com/gtnewhorizons/angelica/glsm/ffp/FragmentKey.java

@@ -135,7 +135,8 @@ public final class FragmentKey {
         int highestEnabled = -1;
         long unit0Bits = 0;
         for (int i = 0; i < MAX_UNITS; i++) {
-            final boolean texEnabled = GLStateManager.getTextures().getTextureUnitStates(i).isEnabled();
+            // Per Mesa - an enabled unit with no complete texture bound counts as disabled.
+            final boolean texEnabled = GLStateManager.getTextures().getTextureUnitStates(i).isEnabled() && GLStateManager.getTextures().getTextureUnitBindings(i).getBinding() != 0;
             if (texEnabled) highestEnabled = i;
 
             final long unitBits = packUnit(i, texEnabled);

glsm/src/test/java/com/gtnewhorizons/angelica/glsm/CompatShaderTransformerTest.java

@@ -1,6 +1,8 @@
 package com.gtnewhorizons.angelica.glsm;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
@@ -613,4 +615,239 @@ class CompatShaderTransformerTest {
         assertFalse(result.matches("(?s).*\\bnew\\b(?!\\s*\\().*"), "'new' as identifier must be renamed in core profile output\n\n" + result);
         assertTrue(result.contains("angelica_renamed_new"), "'new' should be renamed to angelica_renamed_new\n\n" + result);
     }
+
+    private static String compact(String s) {
+        return s.replaceAll("\\s+", "");
+    }
+
+    private static String core(String src) {
+        return compact(CompatShaderTransformer.transform(src, false));
+    }
+
+    private static void assertLoc(String c, int loc, String decl) {
+        assertTrue(c.contains(compact("layout(location=" + loc + ")in" + decl)), decl + " expected at location " + loc + "\n\n" + c);
+    }
+
+    private static void assertNoLoc(String c, int loc, String decl) {
+        assertFalse(c.contains(compact("layout(location=" + loc + ")in" + decl)), decl + " must not be at location " + loc + "\n\n" + c);
+    }
+
+    @Test
+    void testCustomPositionAttributePinnedToLocationZero() {
+        // Betweenlands blshader fix
+        String src = """
+            #version 120
+            attribute vec4 a_position;
+            uniform mat4 u_projMat;
+            uniform vec2 u_outSize;
+            varying vec2 v_texCoord;
+            void main(){
+                gl_Position = u_projMat * vec4(a_position.xy, 0.0, 1.0);
+                v_texCoord = a_position.xy / u_outSize;
+            }
+            """;
+
+        String result = CompatShaderTransformer.transform(src, false);
+        assertLoc(compact(result), 0, "vec4 a_position");
+        assertTrue(result.contains("#version 330 core"), result);
+    }
+
+    @Test
+    void testMultipleLocationlessInputsGetSequentialLocations() {
+        String c = core("""
+            #version 120
+            attribute vec4 a_pos;
+            attribute vec2 a_uv;
+            varying vec2 v_uv;
+            void main() {
+                v_uv = a_uv;
+                gl_Position = vec4(a_pos.xy, 0.0, 1.0);
+            }
+            """);
+        assertLoc(c, 0, "vec4 a_pos");
+        assertLoc(c, 1, "vec2 a_uv");
+    }
+
+    @Test
+    void testCustomInputReservesAroundGlVertex() {
+        String c = core("""
+            #version 120
+            attribute vec4 a_foo;
+            void main() {
+                gl_Position = ftransform() + a_foo;
+            }
+            """);
+        assertLoc(c, 0, "vec4 angelica_Vertex");
+        assertLoc(c, 1, "vec4 a_foo");
+    }
+
+    @Test
+    void testCustomInputSkipsFfpSlots() {
+        String c = core("""
+            #version 120
+            attribute vec4 a_foo;
+            void main() {
+                gl_Position = vec4(a_foo.xy, 0.0, 1.0) + gl_Color;
+            }
+            """);
+        assertLoc(c, 0, "vec4 a_foo");
+        assertLoc(c, 1, "vec4 angelica_Color");
+    }
+
+    @Test
+    void testExplicitLowLocationReserved() {
+        String c = core("""
+            #version 120
+            layout(location = 0) in vec4 a_x;
+            attribute vec4 a_y;
+            void main() {
+                gl_Position = a_x + a_y;
+            }
+            """);
+        assertLoc(c, 0, "vec4 a_x");
+        assertLoc(c, 1, "vec4 a_y");
+    }
+
+    @Test
+    void testMatrixInputSortedFirst() {
+        String c = core("""
+            #version 120
+            attribute vec4 a_a;
+            attribute mat4 a_m;
+            void main() {
+                gl_Position = a_m * a_a;
+            }
+            """);
+        assertLoc(c, 0, "mat4 a_m");   // 4-slot matrix sorted first
+        assertLoc(c, 4, "vec4 a_a");
+    }
+
+    @Test
+    void testInputNamedLocationStillPinned() {
+        assertLoc(core("""
+            #version 120
+            attribute vec4 a_location;
+            void main() {
+                gl_Position = vec4(a_location.xy, 0.0, 1.0);
+            }
+            """), 0, "vec4 a_location");
+    }
+
+    @Test
+    void testInputWithExplicitLayoutLeftAlone() {
+        String c = core("""
+            #version 120
+            layout(location = 3) in vec4 a_data;
+            attribute vec4 a_position;
+            varying vec2 v_uv;
+            void main() {
+                v_uv = a_data.xy;
+                gl_Position = vec4(a_position.xy, 0.0, 1.0);
+            }
+            """);
+        assertLoc(c, 0, "vec4 a_position");   // sole location-less input
+        assertLoc(c, 3, "vec4 a_data");       // explicit location preserved
+        assertNoLoc(c, 0, "vec4 a_data");
+    }
+
+    @Test
+    void testPinnedShaderRemainsWellFormed() {
+        String src = """
+            #version 120
+            attribute vec4 a_position;
+            void main() {
+                gl_FrontColor = gl_Color;
+                gl_TexCoord[0] = gl_MultiTexCoord0;
+                gl_Position = gl_ModelViewMatrix * vec4(a_position.xyz, 1.0);
+            }
+            """;
+
+        String result = CompatShaderTransformer.transform(src, false);
+        String c = compact(result);
+        assertLoc(c, 0, "vec4 a_position");
+        assertLoc(c, 1, "vec4 angelica_Color");
+        assertTrue(c.contains("uniformmat4angelica_ModelViewMatrix"), "matrix uniform injected\n\n" + result);
+        assertFalse(c.contains("gl_ModelViewMatrix"), "builtin rewritten (not fallback)\n\n" + result);
+
+        final int mainIdx = result.indexOf("void main");
+        assertTrue(mainIdx > 0, result);
+        assertTrue(result.indexOf("angelica_ModelViewMatrix") < mainIdx, "uniform before main\n\n" + result);
+        assertTrue(result.indexOf("a_position") < mainIdx, "pinned input before main\n\n" + result);
+    }
+
+    @Test
+    void testGlVertexShaderDoesNotPinCustomAttribute() {
+        String c = core("""
+            #version 120
+            attribute float activelights;
+            void main() {
+                gl_Position = ftransform();
+                float x = activelights;
+            }
+            """);
+        assertLoc(c, 0, "vec4 angelica_Vertex");
+        assertNoLoc(c, 0, "float activelights");
+    }
+
+    @ParameterizedTest   // array on the declarator (vec4 a[2]) and on the type (vec4[2] a) must both round-trip
+    @ValueSource(strings = {"attribute vec4 positions[2];", "attribute vec4[2] positions;"})
+    void testArrayAttributePreservedEitherSyntax(String decl) {
+        String c = core("""
+            #version 120
+            %s
+            attribute vec4 a_tail;
+            void main() {
+                gl_Position = positions[0] + positions[1] + a_tail;
+            }
+            """.formatted(decl));
+        assertLoc(c, 0, "vec4 positions[2]");   // 2-slot array pinned to 0..1
+        assertLoc(c, 2, "vec4 a_tail");
+    }
+
+    @Test
+    void testMultiDeclaratorSplitIntoSeparateLocations() {
+        String result = CompatShaderTransformer.transform("""
+            #version 120
+            attribute vec4 a, b;
+            void main() {
+                gl_Position = a + b;
+            }
+            """, false);
+        String c = compact(result);
+        assertLoc(c, 0, "vec4 a");
+        assertLoc(c, 1, "vec4 b");
+        assertFalse(result.matches("(?s).*\\battribute\\b.*"), "no deprecated 'attribute' keyword may survive\n\n" + result);
+        assertTrue(result.contains("#version 330 core"), result);
+    }
+
+    @Test
+    void testMultiDeclaratorWithMixedArray() {
+        String result = CompatShaderTransformer.transform("""
+            #version 120
+            attribute vec4 a, b[2];
+            void main() {
+                gl_Position = a + b[0] + b[1];
+            }
+            """, false);
+        String c = compact(result);
+        // b takes 2 slots; sorted before the 1-slot a, so b -> 0..1, a -> 2.
+        assertLoc(c, 0, "vec4 b[2]");
+        assertLoc(c, 2, "vec4 a");
+        assertFalse(result.matches("(?s).*\\battribute\\b.*"), "no deprecated 'attribute' keyword may survive\n\n" + result);
+    }
+
+    @Test
+    void testHexExplicitLocationReserved() {
+        String c = core("""
+            #version 120
+            layout(location = 0x1) in vec4 a_x;
+            attribute vec4 a_y;
+            void main() {
+                gl_Position = a_x + a_y;
+            }
+            """);
+        assertTrue(c.contains("layout(location=0x1)invec4a_x"), "hex explicit location preserved\n\n" + c);
+        assertNoLoc(c, 1, "vec4 a_y");   // must not collide with the hex-reserved slot
+        assertLoc(c, 0, "vec4 a_y");
+    }
 }

glsm/src/test/java/com/gtnewhorizons/angelica/glsm/ffp/FFPCombineShaderTest.java

@@ -28,6 +28,7 @@ class FFPCombineShaderTest {
 
     private final List<Integer> shadersToDelete = new ArrayList<>();
     private final List<Integer> programsToDelete = new ArrayList<>();
+    private final List<Integer> texturesToDelete = new ArrayList<>();
 
     @AfterEach
     void cleanup() {
@@ -37,15 +38,25 @@ class FFPCombineShaderTest {
         programsToDelete.clear();
         shadersToDelete.clear();
 
-        // Reset texture units to defaults
+        // Reset texture units to defaults (unbind so a later test does not see a stale binding)
         for (int i = 3; i >= 0; i--) {
             GLStateManager.glActiveTexture(GL13.GL_TEXTURE0 + i);
+            GLStateManager.glBindTexture(GL11.GL_TEXTURE_2D, 0);
             GLStateManager.getTextures().getTexEnvState(i).reset();
             if (i > 0) {
                 GLStateManager.getTextures().getTextureUnitStates(i).disable();
             }
         }
         GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
+        for (int t : texturesToDelete) GL11.glDeleteTextures(t);
+        texturesToDelete.clear();
+    }
+
+    private int bindUnitTexture() {
+        final int tex = GL11.glGenTextures();
+        texturesToDelete.add(tex);
+        GLStateManager.glBindTexture(GL11.GL_TEXTURE_2D, tex);
+        return tex;
     }
 
     @Test
@@ -113,6 +124,7 @@ class FFPCombineShaderTest {
     void testSingleUnitCombineCompiles() {
         GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
         GLStateManager.enableTexture();
+        bindUnitTexture();
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL11.GL_TEXTURE_ENV_MODE, GL13.GL_COMBINE);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_RGB, GL11.GL_MODULATE);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_ALPHA, GL11.GL_MODULATE);
@@ -169,6 +181,7 @@ class FFPCombineShaderTest {
     void testAllCombineFunctionsCompile(String name, int glFunc, int numArgs) {
         GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
         GLStateManager.enableTexture();
+        bindUnitTexture();
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL11.GL_TEXTURE_ENV_MODE, GL13.GL_COMBINE);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_RGB, glFunc);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_ALPHA, GL11.GL_REPLACE);
@@ -202,6 +215,7 @@ class FFPCombineShaderTest {
     void testCombineScopeDeclaresColorOutsideBlock() {
         GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
         GLStateManager.enableTexture();
+        bindUnitTexture();
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL11.GL_TEXTURE_ENV_MODE, GL13.GL_COMBINE);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_RGB, GL11.GL_MODULATE);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_ALPHA, GL11.GL_MODULATE);
@@ -258,6 +272,7 @@ class FFPCombineShaderTest {
         // Unit 0: COMBINE / SUBTRACT
         GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
         GLStateManager.enableTexture();
+        bindUnitTexture();
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL11.GL_TEXTURE_ENV_MODE, GL13.GL_COMBINE);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_RGB, GL13.GL_SUBTRACT);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_ALPHA, GL11.GL_REPLACE);
@@ -273,6 +288,7 @@ class FFPCombineShaderTest {
         // Unit 2: COMBINE / ADD
         GLStateManager.glActiveTexture(GL13.GL_TEXTURE2);
         GLStateManager.enableTexture();
+        bindUnitTexture();
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL11.GL_TEXTURE_ENV_MODE, GL13.GL_COMBINE);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_RGB, GL11.GL_ADD);
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL13.GL_COMBINE_ALPHA, GL11.GL_REPLACE);
@@ -286,6 +302,7 @@ class FFPCombineShaderTest {
         // Unit 3: simple MODULATE
         GLStateManager.glActiveTexture(GL13.GL_TEXTURE3);
         GLStateManager.enableTexture();
+        bindUnitTexture();
         GLStateManager.glTexEnvi(GL11.GL_TEXTURE_ENV, GL11.GL_TEXTURE_ENV_MODE, GL11.GL_MODULATE);
 
         // Restore active unit

glsm/src/test/java/com/gtnewhorizons/angelica/glsm/ffp/FFPUnboundTextureUnitTest.java

@@ -0,0 +1,72 @@
+package com.gtnewhorizons.angelica.glsm.ffp;
+
+import com.gtnewhorizons.angelica.glsm.GLSMCoreExtension;
+import com.gtnewhorizons.angelica.glsm.GLStateManager;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL13;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+@ExtendWith(GLSMCoreExtension.class)
+class FFPUnboundTextureUnitTest {
+
+    private final List<Integer> texturesToDelete = new ArrayList<>();
+
+    @AfterEach
+    void cleanup() {
+        for (int i = 3; i >= 0; i--) {
+            GLStateManager.glActiveTexture(GL13.GL_TEXTURE0 + i);
+            GLStateManager.glBindTexture(GL11.GL_TEXTURE_2D, 0);
+            if (i > 0) GLStateManager.getTextures().getTextureUnitStates(i).disable();
+        }
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
+        for (int t : texturesToDelete) GL11.glDeleteTextures(t);
+        texturesToDelete.clear();
+    }
+
+    private void bindUnitTexture() {
+        final int tex = GL11.glGenTextures();
+        texturesToDelete.add(tex);
+        GLStateManager.glBindTexture(GL11.GL_TEXTURE_2D, tex);
+    }
+
+    @Test
+    void enabledUnitWithoutTextureIsExcluded() {
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
+        GLStateManager.enableTexture();
+        bindUnitTexture();
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE2);
+        GLStateManager.enableTexture(); // enabled, nothing bound
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE3);
+        GLStateManager.enableTexture(); // enabled, nothing bound
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
+
+        final FragmentKey fk = FragmentKey.fromState();
+        assertEquals(1, fk.nrEnabledUnits(), "units 2/3 have no texture bound -> excluded -> only unit 0");
+        assertEquals(0b0001, fk.enabledUnitMask(), "only unit 0 in the key; enabled-but-unbound units 2/3 excluded");
+        assertTrue(fk.unitEnabled(0), "unit 0 (texture bound) stays enabled");
+    }
+
+    @Test
+    void enabledUnitsWithTextureAreCounted() {
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
+        GLStateManager.enableTexture();
+        bindUnitTexture();
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE2);
+        GLStateManager.enableTexture();
+        bindUnitTexture();
+        GLStateManager.glActiveTexture(GL13.GL_TEXTURE0);
+
+        final FragmentKey fk = FragmentKey.fromState();
+        assertTrue(fk.unitEnabled(0));
+        assertTrue(fk.unitEnabled(2), "unit 2 with a bound texture must be counted");
+        assertEquals(3, fk.nrEnabledUnits(), "highest enabled is unit 2 -> nrEnabledUnits=3");
+    }
+}