GL: Fix fallback when glDrawRangeElementsBaseVertex is absent

include/PICA/pica_simd.hpp

@@ -255,18 +255,18 @@ namespace PICA::IndexBuffer {
 	// So we need to subtract the base vertex index from every index in the index buffer ourselves
 	// This is not really common, so we do it without SIMD for the moment, just to be able to run on Android Studio
 	template <bool useShortIndices>
-	void subtractBaseIndex(u8* indexBuffer, u32 vertexCount, u16 baseIndex) {
+	void subtractBaseIndex(u8* indexBuffer, u32 indexCount, u16 baseIndex) {
 		// Calculate the minimum and maximum indices used in the index buffer, so we'll only upload them
 		if constexpr (useShortIndices) {
 			u16* indexBuffer16 = reinterpret_cast<u16*>(indexBuffer);
 
-			for (u32 i = 0; i < vertexCount; i++) {
+			for (u32 i = 0; i < indexCount; i++) {
 				indexBuffer16[i] -= baseIndex;
 			}
 		} else {
 			u8 baseIndex8 = u8(baseIndex);
 
-			for (u32 i = 0; i < vertexCount; i++) {
+			for (u32 i = 0; i < indexCount; i++) {
 				indexBuffer[i] -= baseIndex8;
 			}
 		}

include/renderer_gl/gl_driver.hpp

@@ -6,8 +6,6 @@ namespace OpenGL {
 	struct Driver {
 		bool supportsExtFbFetch = false;
 		bool supportsArmFbFetch = false;
-		// Does this driver support glDraw(Range)ElementsBaseVertex?
-		bool supportsDrawElementsBaseVertex = false;
 
 		bool supportFbFetch() const { return supportsExtFbFetch || supportsArmFbFetch; }
 	};

src/core/renderer_gl/renderer_gl.cpp

@@ -195,7 +195,6 @@ void RendererGL::initGraphicsContextInternal() {
 	// Populate our driver info structure
 	driverInfo.supportsExtFbFetch = (GLAD_GL_EXT_shader_framebuffer_fetch != 0);
 	driverInfo.supportsArmFbFetch = (GLAD_GL_ARM_shader_framebuffer_fetch != 0);
-	driverInfo.supportsDrawElementsBaseVertex = (glDrawRangeElementsBaseVertex != nullptr);
 
 	// Initialize the default vertex shader used with shadergen
 	std::string defaultShadergenVSSource = fragShaderGen.getDefaultVertexShader();
@@ -531,7 +530,7 @@ void RendererGL::drawVertices(PICA::PrimType primType, std::span<const Vertex> v
 				// If glDrawRangeElementsBaseVertex is not available then prepareForDraw will have subtracted the base vertex from the index buffer
 				// for us, so just use glDrawRangeElements
 				glDrawRangeElements(
-					primitiveTopology, 0, maximumIndex - minimumIndex, GLsizei(vertices.size()),
+					primitiveTopology, 0, GLint(maximumIndex - minimumIndex), GLsizei(vertices.size()),
 					usingShortIndices ? GL_UNSIGNED_SHORT : GL_UNSIGNED_BYTE, hwIndexBufferOffset
 				);
 			}
@@ -1183,9 +1182,10 @@ void RendererGL::accelerateVertexUpload(ShaderUnit& shaderUnit, PICA::DrawAccele
 
 		std::memcpy(indexBufferRes.pointer, accel->indexBuffer, indexBufferSize);
 		// If we don't have glDrawRangeElementsBaseVertex, we must subtract the base index value from our index buffer manually
-		if (!driverInfo.supportsDrawElementsBaseVertex) [[unlikely]] {
-			usingShortIndices ? PICA::IndexBuffer::subtractBaseIndex<true>((u8*)indexBufferRes.pointer, vertexCount, accel->minimumIndex)
-							  : PICA::IndexBuffer::subtractBaseIndex<false>((u8*)indexBufferRes.pointer, vertexCount, accel->minimumIndex);
+		if (glDrawRangeElementsBaseVertex == nullptr) [[unlikely]] {
+			const u32 indexCount = regs[PICA::InternalRegs::VertexCountReg];
+			usingShortIndices ? PICA::IndexBuffer::subtractBaseIndex<true>((u8*)indexBufferRes.pointer, indexCount, accel->minimumIndex)
+							  : PICA::IndexBuffer::subtractBaseIndex<false>((u8*)indexBufferRes.pointer, indexCount, accel->minimumIndex);
 		}
 
 		hwIndexBuffer->Unmap(indexBufferSize);